subject:(ANTIMICROBIAL RESISTANCE)

University of Ottawa

1. Laskey, Alexander. Horizontal Transfer of β-Lactam Resistance in the Mouse Gut Microbiota Under Antibiotic Treatment.

Degree: MSc, Médecine / Medicine, 2020, University of Ottawa

URL: http://dx.doi.org/10.20381/ruor-25628

► The rise of β-lactam-resistant bacteria from agricultural settings, including food-producing animals and their related food products has become a significant public health concern. Consumption of… (more)

▼ The rise of β-lactam-resistant bacteria from agricultural settings, including food-producing animals and their related food products has become a significant public health concern. Consumption of food contaminated by such bacteria may cause infection as well as the transmission of resistance genes. Here we used a mouse model to assess the impact of different antibiotic treatments on the composition of the gut microbiota and any impact on the transfer of β-lactam resistance genes between donor and recipient bacteria. Mice were inoculated with β-lactam resistant Escherichia coli and an antibiotic-susceptible Salmonella Heidelberg strain. The mice were treated with either streptomycin, ampicillin or both antibiotics. Mouse feces were collected at regular intervals and processed using selective culture techniques to capture potential transfer of resistance genes. Gene transfer was confirmed by whole genome sequencing. DNA extracted from the feces was used for monitoring changes in microbial profiles by 16S rDNA sequencing. In the absence of antibiotic treatment, the inoculated bacteria were only transiently detected and no transconjugants were recovered from the mouse feces. In comparison, antibiotic treatment changed microbial profiles in the mouse gut, enhanced colonization of the bacterial isolates, and facilitated the transfer of the resistance genes into both S. Heidelberg and commensal E. coli recipient strains. The results of this study indicated that the use of multiple antibiotics may enhance infection of opportunistic β-lactam resistant bacterial pathogens relative to single antibiotics and pose a greater risk in terms of antibiotic resistance gene transfer. Such process might occur in clinical settings where patients are under prolonged antibiotic treatments. Information gained through this study together with future work will inform the development of new policies guiding the prudent use of antibiotics. Advisors/Committee Members: Lin, Min (supervisor), Wang, Lisheng (supervisor).

Subjects/Keywords: Antimicrobial Resistance

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APA (6^th Edition):

Laskey, A. (2020). Horizontal Transfer of β-Lactam Resistance in the Mouse Gut Microbiota Under Antibiotic Treatment. (Masters Thesis). University of Ottawa. Retrieved from http://dx.doi.org/10.20381/ruor-25628

Chicago Manual of Style (16^th Edition):

Laskey, Alexander. “Horizontal Transfer of β-Lactam Resistance in the Mouse Gut Microbiota Under Antibiotic Treatment.” 2020. Masters Thesis, University of Ottawa. Accessed January 16, 2021. http://dx.doi.org/10.20381/ruor-25628.

MLA Handbook (7^th Edition):

Laskey, Alexander. “Horizontal Transfer of β-Lactam Resistance in the Mouse Gut Microbiota Under Antibiotic Treatment.” 2020. Web. 16 Jan 2021.

Vancouver:

Laskey A. Horizontal Transfer of β-Lactam Resistance in the Mouse Gut Microbiota Under Antibiotic Treatment. [Internet] [Masters thesis]. University of Ottawa; 2020. [cited 2021 Jan 16]. Available from: http://dx.doi.org/10.20381/ruor-25628.

Council of Science Editors:

Laskey A. Horizontal Transfer of β-Lactam Resistance in the Mouse Gut Microbiota Under Antibiotic Treatment. [Masters Thesis]. University of Ottawa; 2020. Available from: http://dx.doi.org/10.20381/ruor-25628

University of Melbourne

2. Hardefeldt, Laura Yvonne. Antimicrobial stewardship in Australian veterinary practices.

Degree: 2017, University of Melbourne

URL: http://hdl.handle.net/11343/198446

► Antimicrobial use by the veterinary profession has been coming under increasing scrutiny by medical, public health and government officials as the threat of antimicrobial resistance… (more)

Subjects/Keywords: antibiotic; antimicrobial resistance

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APA (6^th Edition):

Hardefeldt, L. Y. (2017). Antimicrobial stewardship in Australian veterinary practices. (Doctoral Dissertation). University of Melbourne. Retrieved from http://hdl.handle.net/11343/198446

Chicago Manual of Style (16^th Edition):

Hardefeldt, Laura Yvonne. “Antimicrobial stewardship in Australian veterinary practices.” 2017. Doctoral Dissertation, University of Melbourne. Accessed January 16, 2021. http://hdl.handle.net/11343/198446.

MLA Handbook (7^th Edition):

Hardefeldt, Laura Yvonne. “Antimicrobial stewardship in Australian veterinary practices.” 2017. Web. 16 Jan 2021.

Vancouver:

Hardefeldt LY. Antimicrobial stewardship in Australian veterinary practices. [Internet] [Doctoral dissertation]. University of Melbourne; 2017. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/11343/198446.

Council of Science Editors:

Hardefeldt LY. Antimicrobial stewardship in Australian veterinary practices. [Doctoral Dissertation]. University of Melbourne; 2017. Available from: http://hdl.handle.net/11343/198446

University of Guelph

3. Primeau, Courtney. Exploring the contributions of genotypic, phenotypic, social and qualitative data sources to our understanding of antimicrobial resistance in Canada.

Degree: PhD, Department of Population Medicine, 2020, University of Guelph

URL: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/17935

► Antimicrobial resistance (AMR) is a significant global threat to human and veterinary medicine. AMR is a complex health issue, with factors across human and veterinary… (more)

▼ Antimicrobial resistance (AMR) is a significant global threat to human and veterinary medicine. AMR is a complex health issue, with factors across human and veterinary medicine, plant and animal production, and the economy driving the emergence and persistence of resistance. This thesis sought to incorporate diverse methodological approaches, including data sources, methods of analyses, and types of data, and explore how these data could improve our understanding of AMR and its drivers. The primary objectives were to a) evaluate the use of different data sources to improve understanding of AMR, the drivers of AMR, and the interactions between drivers in the overall system, and b) explore perceptions about AMR, key messages to be communicated, and preferred methods of communication about AMR with future antimicrobial prescribers. The methods used included analysis of surveillance data for extended-spectrum beta-lactamase (ESBL)-producing bacteria, synthesis of literature-derived risk factor data for ESBL-producing Escherichia coli in select food-producing animals, analysis of the AMR system using social network analysis, and qualitative exploration of AMR perceptions among future antimicrobial prescribers. The results suggested that overall prevalence of ESBL-producing E. coli and Salmonella in humans and agrifood samples is low, but that ESBLs are widely distributed in agrifood and human sources. There were few studies examining factors associated with ESBL-producing organisms in food-producing animals, highlighting an important research gap. Analysis of the overall AMR system identified key leverage points, including on-farm antimicrobial use and consumer demand for product, that should be explored as targets for future interventions to reduce AMR. Finally, future antimicrobial prescribers felt that AMR is a very important global issue, and that collaboration between sectors is needed to mitigate AMR successfully. These findings highlight the need for ongoing, integrated surveillance and research efforts across food-producing animals, food products, and humans in Canada, including the drivers of use and resistance, to identify emerging trends and assess the relative contribution of different transmission pathways to resistant human infections. Furthermore, the results have important implications for future knowledge translation and communication materials, and can be used to support the development of communication tools that are tailored to the needs of different stakeholders. Advisors/Committee Members: Parmley, Jane (advisor), McEwen, Scott (advisor).

Subjects/Keywords: epidemiology; antimicrobial resistance

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APA (6^th Edition):

Primeau, C. (2020). Exploring the contributions of genotypic, phenotypic, social and qualitative data sources to our understanding of antimicrobial resistance in Canada. (Doctoral Dissertation). University of Guelph. Retrieved from https://atrium.lib.uoguelph.ca/xmlui/handle/10214/17935

Chicago Manual of Style (16^th Edition):

Primeau, Courtney. “Exploring the contributions of genotypic, phenotypic, social and qualitative data sources to our understanding of antimicrobial resistance in Canada.” 2020. Doctoral Dissertation, University of Guelph. Accessed January 16, 2021. https://atrium.lib.uoguelph.ca/xmlui/handle/10214/17935.

MLA Handbook (7^th Edition):

Primeau, Courtney. “Exploring the contributions of genotypic, phenotypic, social and qualitative data sources to our understanding of antimicrobial resistance in Canada.” 2020. Web. 16 Jan 2021.

Vancouver:

Primeau C. Exploring the contributions of genotypic, phenotypic, social and qualitative data sources to our understanding of antimicrobial resistance in Canada. [Internet] [Doctoral dissertation]. University of Guelph; 2020. [cited 2021 Jan 16]. Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/17935.

Council of Science Editors:

Primeau C. Exploring the contributions of genotypic, phenotypic, social and qualitative data sources to our understanding of antimicrobial resistance in Canada. [Doctoral Dissertation]. University of Guelph; 2020. Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/17935

University of Tennessee – Knoxville

4. Samuels, Ronita. An Epidemiologic Study of Antimicrobial Resistance.

Degree: 2019, University of Tennessee – Knoxville

URL: https://trace.tennessee.edu/utk_graddiss/5703

► The emergence of antimicrobial resistant bacteria has become a serious public health concern. The use of antimicrobials for prophylaxis make it important to estimate the… (more)

▼ The emergence of antimicrobial resistant bacteria has become a serious public health concern. The use of antimicrobials for prophylaxis make it important to estimate the magnitude of the problem in the animal population. The aim of the second chapter in this study is to investigate the burden and patterns of antimicrobial resistance (AMR) among equine Staphylococcus samples submitted to the University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) from 1993 to 2009. The proportion of resistant isolates by animal breed, species of organism, sample source, and time period were computed. Chi-square and Cochran-Armitage trend tests were used to identify significant associations and temporal trends, respectively. Logistic regression models were used to investigate predictors of AMR and multidrug resistance (MDR).In addition to the problem of antimicrobial resistant bacteria, appropriate usage of antimicrobials is also a global public health concern where opinions regarding appropriate use vary greatly amongst veterinarians. Therefore, the objectives of the third chapter of this study are to investigate the opinions, knowledge and perceptions of veterinarians in Kentucky regarding AMR and antimicrobial prescription practices as well as to identify predictors of their knowledge and opinions. This cross-sectional study uses a 30-question survey questionnaire administered to members of the Kentucky Veterinary Medical Association (KVMA). The proportion of responses to survey questions and 95% confidence intervals were computed. Predictors of improper use of antimicrobials and antimicrobial prescription practices of the respondents as well as their colleagues were investigated using multinomial logistic regression models.The appropriate usage of antimicrobials is also an important topic in developing countries such as South Africa. Thus, the fourth chapter in this study investigates the knowledge, prescription practices and attitudes towards AMR among veterinarians in the City of Tshwane, Metropolitan Municipality. A 30-question survey was administered and the percentages of responses to survey questions and their 95% confidence intervals will be computed. Ordinary logistic models are used to investigate predictors of knowledge of antimicrobial resistance and antimicrobial prescription practices of respondents. Predictors of antimicrobial prescription practices of respondents’ colleagues are identified using multinomial logistic models.

Subjects/Keywords: Antimicrobial Resistance; multidrug resistance; Staphylococcus

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APA (6^th Edition):

Samuels, R. (2019). An Epidemiologic Study of Antimicrobial Resistance. (Doctoral Dissertation). University of Tennessee – Knoxville. Retrieved from https://trace.tennessee.edu/utk_graddiss/5703

Chicago Manual of Style (16^th Edition):

Samuels, Ronita. “An Epidemiologic Study of Antimicrobial Resistance.” 2019. Doctoral Dissertation, University of Tennessee – Knoxville. Accessed January 16, 2021. https://trace.tennessee.edu/utk_graddiss/5703.

MLA Handbook (7^th Edition):

Samuels, Ronita. “An Epidemiologic Study of Antimicrobial Resistance.” 2019. Web. 16 Jan 2021.

Vancouver:

Samuels R. An Epidemiologic Study of Antimicrobial Resistance. [Internet] [Doctoral dissertation]. University of Tennessee – Knoxville; 2019. [cited 2021 Jan 16]. Available from: https://trace.tennessee.edu/utk_graddiss/5703.

Council of Science Editors:

Samuels R. An Epidemiologic Study of Antimicrobial Resistance. [Doctoral Dissertation]. University of Tennessee – Knoxville; 2019. Available from: https://trace.tennessee.edu/utk_graddiss/5703

University of Guelph

5. Moffat, Jonathan. Frequency and characterization of extended-spectrum cephalosporin- and gentamicin-resistant Enterobacterales from Canadian turkeys and distribution of associated resistance determinants.

Degree: MS, Department of Pathobiology, 2019, University of Guelph

URL: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/17465

► Frequency of gentamicin- and extended-spectrum cephalosporin (ESC)-resistant Enterobacterales in turkey fecal samples following enrichment or direct plating, and from diagnostic isolates, were determined. Gentamicin- and… (more)

Subjects/Keywords: turkeys; E. coli; antimicrobial resistance; antimicrobial stewardship

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APA (6^th Edition):

Moffat, J. (2019). Frequency and characterization of extended-spectrum cephalosporin- and gentamicin-resistant Enterobacterales from Canadian turkeys and distribution of associated resistance determinants. (Masters Thesis). University of Guelph. Retrieved from https://atrium.lib.uoguelph.ca/xmlui/handle/10214/17465

Chicago Manual of Style (16^th Edition):

Moffat, Jonathan. “Frequency and characterization of extended-spectrum cephalosporin- and gentamicin-resistant Enterobacterales from Canadian turkeys and distribution of associated resistance determinants.” 2019. Masters Thesis, University of Guelph. Accessed January 16, 2021. https://atrium.lib.uoguelph.ca/xmlui/handle/10214/17465.

MLA Handbook (7^th Edition):

Moffat, Jonathan. “Frequency and characterization of extended-spectrum cephalosporin- and gentamicin-resistant Enterobacterales from Canadian turkeys and distribution of associated resistance determinants.” 2019. Web. 16 Jan 2021.

Vancouver:

Moffat J. Frequency and characterization of extended-spectrum cephalosporin- and gentamicin-resistant Enterobacterales from Canadian turkeys and distribution of associated resistance determinants. [Internet] [Masters thesis]. University of Guelph; 2019. [cited 2021 Jan 16]. Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/17465.

Council of Science Editors:

Moffat J. Frequency and characterization of extended-spectrum cephalosporin- and gentamicin-resistant Enterobacterales from Canadian turkeys and distribution of associated resistance determinants. [Masters Thesis]. University of Guelph; 2019. Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/17465

University of Namibia

6. Shilangale, Renatus P. Prevalence, Serotypes and antimicrobial resistance os Salmonella isolated from beef and small animal feed in Namibia.

Degree: 2014, University of Namibia

URL: http://hdl.handle.net/11070/807

► The occurrence of Salmonella is a global challenge in the public health and food production sectors. Contaminated beef and animal feed with Salmonella may lead… (more)

▼ The occurrence of Salmonella is a global challenge in the public health and food production sectors. Contaminated beef and animal feed with Salmonella may lead to infections of humans through food chain. The present study investigated the prevalence, serovar and antimicrobial resistance of strains of Salmonella serovars isolated from beef (meat cuts, meat fluid and carcass swabs) and animal feed (meat-and-bone, and blood meal) samples from the abattoirs in Namibia. Beef (9508) and animal feed (827) samples were examined for the presence of Salmonella. The data showed that 0.85 % (n= 81) of beef were positive for Salmonella. In animal feed, 11.73 % (n = 97) were positive for Salmonella. The prevalence was higher in carcass swab samples than meat cuts and meat fluid but did not differ significantly (p > 0.05) between the products. However, there was a significant difference (p < 0.05) on the prevalence of Salmonella in blood meal as compared to meat-and-bone meal. Forty-four different types of Salmonella serovars were isolated and identified in this study. However, 23 isolated Salmonella serovars could not be identified conclusively. Of the Salmonella serovars isolated, S.Chester was the most common isolated serovar (18.54 %) followed by S. Schwarzengrund (7.30 %), S. Anatum (5.06 %), S. Typhimurium (4.49 %), S. Braenderup (4.49 %) and S. Reading (4.49 %). From 19 Salmonella serovars which exhibited resistance to one or more types of antimicrobials, 15 different Salmonella serovars exhibited resistance to at least two antimicrobials. Most Salmonella were resistant to sulfisoxazole followed by trimethoprim-sulfamethoxazole and tetracycline whereas, 80.3% (n= 57) were susceptible to all 16 antimicrobials tested. Resistance to sulfisoxazole and the trimethroprim-suflamethoxazole combination were the most common. Of all Salmonella isolated, 29.21 % (n = 178) exhibited resistance to the antimicrobials used. The resistant isolates belonged to 19 different Salmonella serovars of which 15 different types of serovars showed multidrug resistance (MDR). From the study it was found that the prevalence of Salmonella in Namibia is comparable to some studies in other countries. Few or no similar studies are available in the Southern African region for comparison. The susceptibility of Salmonella to the antimicrobials tested indicated that antimicrobial resistance is not as common and extensive in Namibia as has been reported in many other countries. It also appears that there is a range of antimicrobials available that are effective in managing Salmonella infections in Namibia. However, there is some evidence that resistance is developing and this will need further monitoring to ensure it does not escalate to a problem. This study has helped to understand the prevalence of Salmonella serovars in Namibia and how their antimicrobial resistance pattern may influence on the selection of drugs and the treatment of salmonellosis in humans and animals. It is recommended that continuous studies to be done to monitor the link between the…

Subjects/Keywords: Serotypes ; Antimicrobial resistance ; Salmonella ; Salmonella

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APA (6^th Edition):

Shilangale, R. P. (2014). Prevalence, Serotypes and antimicrobial resistance os Salmonella isolated from beef and small animal feed in Namibia. (Thesis). University of Namibia. Retrieved from http://hdl.handle.net/11070/807

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Shilangale, Renatus P. “Prevalence, Serotypes and antimicrobial resistance os Salmonella isolated from beef and small animal feed in Namibia. ” 2014. Thesis, University of Namibia. Accessed January 16, 2021. http://hdl.handle.net/11070/807.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Shilangale, Renatus P. “Prevalence, Serotypes and antimicrobial resistance os Salmonella isolated from beef and small animal feed in Namibia. ” 2014. Web. 16 Jan 2021.

Vancouver:

Shilangale RP. Prevalence, Serotypes and antimicrobial resistance os Salmonella isolated from beef and small animal feed in Namibia. [Internet] [Thesis]. University of Namibia; 2014. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/11070/807.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Shilangale RP. Prevalence, Serotypes and antimicrobial resistance os Salmonella isolated from beef and small animal feed in Namibia. [Thesis]. University of Namibia; 2014. Available from: http://hdl.handle.net/11070/807

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Cornell University

7. Pereira, Richard. The Epidemiology Of Antimicrobial Resistant Enteric Bacteria Of Public Health Significance In Dairy Cattle.

Degree: PhD, Veterinary Medicine, 2015, Cornell University

URL: http://hdl.handle.net/1813/40710

► Multidrug resistant bacterial strains are a current challenge to modern medicine, and according to the Centers for Disease Control and Prevention are responsible for 20… (more)

▼ Multidrug resistant bacterial strains are a current challenge to modern medicine, and according to the Centers for Disease Control and Prevention are responsible for 20 billion in excess healthcare costs, 35 billion in societal costs, and 8 million additional hospital days in the United States. As occurs for clinical use, the administration of antimicrobial drugs in cattle creates selective pressure shown to result, in many cases, in resistance to antimicrobial drugs critically important to human medicine. Furthermore, the use of antimicrobial drugs in food animals, specifically drugs in classes that are also used in human medicine, remains a contentious public health issue. Studies that identify risk factors that increase the rate of selection, amplification and spread of resistance on dairy farms, and generate information to propose intervention to prevent or reduce such undesired outcomes are of vital importance. The studies in this dissertation focused on this knowledge gap and used epidemiology, microbiology and genomic approaches to generated novel data in many priority areas, including (1) prevalence and concentration of drug residues present in the milk commonly fed to dairy calves; (2) impacts of feeding milk with drug residues on selection of resistant bacteria and on the composition of the fecal microbiota of preweaned calves; (3) effect of preweaned dairy calf housing systems on prevalence of antimicrobial resistance; (4) prevalence of resistant E. coli and Salmonella in cattle under different heifer-raising practices; and (5) efficacy of using ultraviolet light as an intervention to reduce pathogens in the milk and colostrum fed to calves. This dissertation supports the view that intended or unintended exposure of cattle to therapeutic and sub-therapeutic concentrations of antimicrobial drugs can select for resistance to antimicrobials of critical importance to veterinary and human medicine. Moreover it encourages the implementation of management practices that improve the health of cattle without the use of antimicrobials, and endorses the judicious use of antimicrobial drugs concomitant with improvement of animal production and wellbeing. Advisors/Committee Members: Warnick,Lorin D (chair), Grohn,Yrjo Tapio (committee member), Stanhope,Michael J (committee member), Altier,Craig (committee member).

Subjects/Keywords: Antimicrobial Resistance; Public Health; Cattle

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APA (6^th Edition):

Pereira, R. (2015). The Epidemiology Of Antimicrobial Resistant Enteric Bacteria Of Public Health Significance In Dairy Cattle. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/40710

Chicago Manual of Style (16^th Edition):

Pereira, Richard. “The Epidemiology Of Antimicrobial Resistant Enteric Bacteria Of Public Health Significance In Dairy Cattle.” 2015. Doctoral Dissertation, Cornell University. Accessed January 16, 2021. http://hdl.handle.net/1813/40710.

MLA Handbook (7^th Edition):

Pereira, Richard. “The Epidemiology Of Antimicrobial Resistant Enteric Bacteria Of Public Health Significance In Dairy Cattle.” 2015. Web. 16 Jan 2021.

Vancouver:

Pereira R. The Epidemiology Of Antimicrobial Resistant Enteric Bacteria Of Public Health Significance In Dairy Cattle. [Internet] [Doctoral dissertation]. Cornell University; 2015. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/1813/40710.

Council of Science Editors:

Pereira R. The Epidemiology Of Antimicrobial Resistant Enteric Bacteria Of Public Health Significance In Dairy Cattle. [Doctoral Dissertation]. Cornell University; 2015. Available from: http://hdl.handle.net/1813/40710

Colorado State University

8. Thomas, Kevin. Characterization of the resistome and microbiome of retail meats processed from carcasses of conventionally and naturally raised cattle.

Degree: MS(M.S.), Animal Sciences, 2019, Colorado State University

URL: http://hdl.handle.net/10217/195254

► Concern over human exposure to antimicrobial resistance (AMR) via consumption of meat products has raised questions about use of antimicrobial drugs in food-animal production. This… (more)

▼ Concern over human exposure to antimicrobial resistance (AMR) via consumption of meat products has raised questions about use of antimicrobial drugs in food-animal production. This concern has led to an increase in consumer demand for meat products from naturally-raised cattle, or those raised without use of antimicrobials. While previous studies have assessed AMR gene presence in cattle and throughout the beef supply chain, very little work has surveyed the resistome on retail meats available for consumer purchase. The objective of this study was to determine the extent of antimicrobial resistance and characterize the microbiome in retail ground beef products from naturally-raised (raised without antibiotics) and conventionally-raised cattle utilizing 16S rRNA and targeted shotgun metagenomic, high-throughput sequencing techniques. Differing in packaging types and lean points, samples of ground beef derived from carcasses of cattle that were conventionally-raised (n = 50) or naturally-raised cattle (n = 50) were purchased from retail outlets in six major metropolitan cities throughout the United States. Samples were shipped to Colorado State University and processed following 48 hours of refrigeration at 4°C. Thirty-gram portions of each sample were removed and subjected to DNA extraction procedures via DNeasy PowerFecal Microbial Kit. Cell lysates were composited by production system and city before being subjected to paired-end 16S rRNA gene sequencing and targeted shotgun metagenomic sequencing using an enrichment system developed in our laboratory. Microbiome analysis was performed from 16S data with QIIME2 v.2018.4 by utilizing many of the available plugins. Resistome analysis of enriched metagenomic data was performed using a modified AMRPlusPlus pipeline. Microbiome alpha diversity analysis indicated that ground beef processed from conventionally-raised animals had a greater (P < 0.05) species richness than natural ground beef products. Microbiome composition differed (P < 0.05) between samples of differing production systems based on abundance weighted UniFrac distances. Additionally, when analyzed using unweighted UniFrac distances, microbial composition differed (P < 0.05) between samples from different cities. Differences in product packaging availability between cities may have caused these differences detected in microbiome composition, as well as environmental contamination or product handling in distribution. Targeted shotgun sequencing yielded a total of 4.6 trillion reads across all 60 composite samples, with only 58 samples containing hits to AMR. Of these 58 samples, 10.1 million reads were assigned to: 520 groups, 101 mechanisms of resistance, and 22 classes of antibiotics. The three most abundant classes of resistance detected included tetracyclines (56% of assigned reads), multi-drug resistance (21% of reads), and beta-lactams (7% of reads). An analysis of similarity on samples ordinated using Euclidian distances suggested that the overall resistome differed (P < 0.05) by production system,… Advisors/Committee Members: Belk, Keith (advisor), Morley, Paul (committee member), Metcalf, Jessica (committee member).

Subjects/Keywords: meatagenomics; resistome; microbiome; antimicrobial resistance

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APA (6^th Edition):

Thomas, K. (2019). Characterization of the resistome and microbiome of retail meats processed from carcasses of conventionally and naturally raised cattle. (Masters Thesis). Colorado State University. Retrieved from http://hdl.handle.net/10217/195254

Chicago Manual of Style (16^th Edition):

Thomas, Kevin. “Characterization of the resistome and microbiome of retail meats processed from carcasses of conventionally and naturally raised cattle.” 2019. Masters Thesis, Colorado State University. Accessed January 16, 2021. http://hdl.handle.net/10217/195254.

MLA Handbook (7^th Edition):

Thomas, Kevin. “Characterization of the resistome and microbiome of retail meats processed from carcasses of conventionally and naturally raised cattle.” 2019. Web. 16 Jan 2021.

Vancouver:

Thomas K. Characterization of the resistome and microbiome of retail meats processed from carcasses of conventionally and naturally raised cattle. [Internet] [Masters thesis]. Colorado State University; 2019. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/10217/195254.

Council of Science Editors:

Thomas K. Characterization of the resistome and microbiome of retail meats processed from carcasses of conventionally and naturally raised cattle. [Masters Thesis]. Colorado State University; 2019. Available from: http://hdl.handle.net/10217/195254

McMaster University

9. Stalteri, Rosa. ANTIMICROBIAL RESISTANCE AND GUIDELINE RECOMMENDATIONS: CONTEXTUALIZATION AND ADAPTABILITY.

Degree: MPH, 2020, McMaster University

URL: http://hdl.handle.net/11375/25524

►

BACKGROUND: Antibiotics are essential medicines and their effectiveness is under threat due to antimicrobial resistance. Guidelines are one way to conserve antibiotic effectiveness given that… (more)

▼

BACKGROUND: Antibiotics are essential medicines and their effectiveness is under threat due to antimicrobial resistance. Guidelines are one way to conserve antibiotic effectiveness given that they are intended to modify clinician prescribing. Guidelines that provide antibiotic recommendations should make explicit contextual considerations that influence antimicrobial resistance and their downstream effects on resistance emergence. METHODS: We conducted a systematic review of tuberculosis, gonorrhoea, and respiratory tract infection guidelines and recommendations to examine how and to what extent they are considering contextual factors that influence antimicrobial resistance. We also investigated whether there are guidelines and recommendations that can be adopted or adapted to local contexts. RESULTS: We found that within 74 included guidelines, two thirds of recommendations considered antimicrobial resistance. Of which only five guidelines considered all factors required to consider local aspects such as values, resource use, acceptability, feasibility, and equity. As such, these five guidelines can be either adopted or adapted to Canadian and other contexts. We also found that 39% of guidelines met credibility scores of 60% or greater in AGREE II domains: scope and purpose, rigor of development, and editorial independence. CLINCAL IMPLICATIONS: There are very few Infectious disease guidelines for highly prevalent diseases that do not consider all important contextual factors may influence antimicrobial resistance. Our findings can support societies and organizations, public health policy, and health care stakeholders to develop and implement guidelines that are applicable to local contexts efficiently and resourcefully. Our antimicrobial resistance recommendation framework, used in addition to GRADE Evidence to Decision frameworks, is a start to having this come to fruition.

Thesis

Master of Public Health (MPH)

Advisors/Committee Members: Schünemann, Holger, Health Research Methodology.

Subjects/Keywords: Guidelines; Recommendations; Antimicrobial resistance; Contextual

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APA (6^th Edition):

Stalteri, R. (2020). ANTIMICROBIAL RESISTANCE AND GUIDELINE RECOMMENDATIONS: CONTEXTUALIZATION AND ADAPTABILITY. (Masters Thesis). McMaster University. Retrieved from http://hdl.handle.net/11375/25524

Chicago Manual of Style (16^th Edition):

Stalteri, Rosa. “ANTIMICROBIAL RESISTANCE AND GUIDELINE RECOMMENDATIONS: CONTEXTUALIZATION AND ADAPTABILITY.” 2020. Masters Thesis, McMaster University. Accessed January 16, 2021. http://hdl.handle.net/11375/25524.

MLA Handbook (7^th Edition):

Stalteri, Rosa. “ANTIMICROBIAL RESISTANCE AND GUIDELINE RECOMMENDATIONS: CONTEXTUALIZATION AND ADAPTABILITY.” 2020. Web. 16 Jan 2021.

Vancouver:

Stalteri R. ANTIMICROBIAL RESISTANCE AND GUIDELINE RECOMMENDATIONS: CONTEXTUALIZATION AND ADAPTABILITY. [Internet] [Masters thesis]. McMaster University; 2020. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/11375/25524.

Council of Science Editors:

Stalteri R. ANTIMICROBIAL RESISTANCE AND GUIDELINE RECOMMENDATIONS: CONTEXTUALIZATION AND ADAPTABILITY. [Masters Thesis]. McMaster University; 2020. Available from: http://hdl.handle.net/11375/25524

University of Saskatchewan

10. Jung, Dongyun 1990-. Antimicrobial resistant bacteria from imported vegetables and spices purchased from niche markets in Saskatoon, Saskatchewan.

Degree: 2019, University of Saskatchewan

URL: http://hdl.handle.net/10388/11862

► The role of imported vegetables and spices in the epidemiology of antimicrobial resistance in Canada has been inadequately studied. In this investigation, resistant organisms from… (more)

▼ The role of imported vegetables and spices in the epidemiology of antimicrobial resistance in Canada has been inadequately studied. In this investigation, resistant organisms from imported vegetables and spices in Saskatoon, Saskatchewan were investigated. A total of 147 vegetable and spice products imported from primarily Asian and African countries, were purchased from international markets in Saskatoon, Saskatchewan. Samples were selectively cultured for a panel of bacteria where resistance is known to be emerging. The proportion of samples positive for each organism were as follows: E. coli (n=15, 10.2%), Salmonella spp. (n=2, 1.4%), Enterobacter spp. (n=12, 8.2%), K. pneumoniae (n=2, 1.4%), Acinetobacter spp. (n=12, 8.2%), Pseudomonas spp. (n=10, 6.8%), S. aureus (n=7, 4.8%) and Enterococcus spp. (n=69, 46.9%). Antimicrobial susceptibility testing of isolates was conducted by broth micro dilution and agar dilution. Based on the susceptibility of each organism, isolates were then screened for resistance genes (β-lactamases and plasmid mediated quinolones resistance determinants) by PCR. Multidrug resistant Enterobacteriaceae were identified. Among other organisms, methicillin resistant S. aureus (MRSA) were identified. Resistance to the penicillins, cephalosporins, quinolones and aminoglycosides mediated by broad spectrum β-lactamases and plasmid mediated quinolone resistance determinants (PMQR) were identified. Broad spectrum β-lactamase producers were cultured from 6/147 (4.1%) of samples tested. The most common enzymes found were CTX-M-15 (n=4), TEM-4 (n=1) and SHV-142 (n=1). The PMQRs (QnrB1, QnrB2, QnrS1 and AAC(6’)-Ib-cr) containing isolates were cultured from 2/147 (1.4%) of the samples. While all multi-drug resistant Enterobacteriaceae isolates were susceptible to meropenem and colistin, several non-fermenters were resistant to these drugs. However, none of these organisms produced carbapenemases or possessed mobilized colistin resistance determinants (MCR-1, MCR-2, MCR-3, MCR-4). Salmonella spp. were susceptible to the most of tested drugs. With the exception of two MRSA, the S. aureus isolates were susceptible to other non-beta lactam drugs. Enterococcus spp. isolates were resistant to various drugs but susceptible to ampicillin, penicillin and vancomycin. It was interesting to observe that all of the multi-drug resistant organisms originated from countries which are recognized to have a high prevalence of resistance. Therefore, further study is required to understand the extent of antimicrobial resistance transmission by imported vegetables and spices from these countries to Canada. Advisors/Committee Members: Gow, Sheryl, Gerdts, Volker, Blondeau, Joseph.

Subjects/Keywords: Antimicrobial resistance; Imported foods

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APA (6^th Edition):

Jung, D. 1. (2019). Antimicrobial resistant bacteria from imported vegetables and spices purchased from niche markets in Saskatoon, Saskatchewan. (Thesis). University of Saskatchewan. Retrieved from http://hdl.handle.net/10388/11862

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Jung, Dongyun 1990-. “Antimicrobial resistant bacteria from imported vegetables and spices purchased from niche markets in Saskatoon, Saskatchewan.” 2019. Thesis, University of Saskatchewan. Accessed January 16, 2021. http://hdl.handle.net/10388/11862.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Jung, Dongyun 1990-. “Antimicrobial resistant bacteria from imported vegetables and spices purchased from niche markets in Saskatoon, Saskatchewan.” 2019. Web. 16 Jan 2021.

Vancouver:

Jung D1. Antimicrobial resistant bacteria from imported vegetables and spices purchased from niche markets in Saskatoon, Saskatchewan. [Internet] [Thesis]. University of Saskatchewan; 2019. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/10388/11862.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Jung D1. Antimicrobial resistant bacteria from imported vegetables and spices purchased from niche markets in Saskatoon, Saskatchewan. [Thesis]. University of Saskatchewan; 2019. Available from: http://hdl.handle.net/10388/11862

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Oxford

11. Le, Nhi Thi Quynh. Diarrhoeal disease in children under five years of age in an urban community in Viet Nam.

Degree: PhD, 2018, University of Oxford

URL: http://ora.ox.ac.uk/objects/uuid:438b4e93-1c55-4e1d-acc2-b425ff7402ef ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.780685

► Antimicrobial resistance (AMR) in infectious disease is a major global health issue. AMR is a particular problem in low to middle-income countries (LMICs), where infectious… (more)

▼ Antimicrobial resistance (AMR) in infectious disease is a major global health issue. AMR is a particular problem in low to middle-income countries (LMICs), where infectious diseases, such as diarrhoea, remain common and are commonly treated haphazardly with antimicrobials. The aim of my thesis was to provide a comprehensive study of diarrhoeal disease in children under the age of five years in the community in Ho Chi Minh City (HCMC), Viet Nam. Additionally, I aimed to fill in a knowledge gap regarding antimicrobial usage for diarrhoea, the extent of AMR organisms in healthy children within the population, and investigate a potential solution for limiting AMR in the community. Active surveillance for diarrhoea in a prospective longitudinal cohort of 748 children followed for 24 months found a high incidence of diarrhoeal disease in the urban community (71.87/100 child-years of observation [95%CI: 65.68 -78.44]). Faecal samples were screened using conventional microbiology and multiplex molecular methods and found that the aetiology of this disease is highly variable. Pathogenic bacteria and viruses were detected at a high prevalence, but the most common were Salmonella and norovirus, respectively. Antimicrobials were commonly used for diarrhoeal treatment in hospital. Additionally, a mixed-methods approach in the community found an ease of access to antimicrobials for diarrhoeal management in the community through local pharmacies. However, despite antimicrobials being widely available in the community, antimicrobial usage was almost 10 times greater in the hospitals. Widespread antimicrobial access may induce the selection of antimicrobial resistant organisms (AROs) and antimicrobial resistance genes (ARGs). An assessment of the prevalence of and risk factors for carrying AROs and ARGs demonstrated a high prevalence of carriage antimicrobial resistant Escherichia coli (E. coli) and associated resistance genes to fluoroquinolones and third generation cephalosporins. Both these groups are commonly used to treat diarrhoea in this setting. Children of higher body weight and height z-score were more likely to carry fluoroquinolones resistance genes and younger children were more likely to carry either third generation cephalosporin resistance genes individually or in combination with fluoroquinolones resistance genes. Lastly, hypothesising that improved breastfeeding practices may reduce diarrhoeal disease and impact antimicrobial usage and consequently AMR, I investigated risk factors for suboptimal breastfeeding using data from a birth cohort conducted in both an urban and a semi-rural area. The study indicated that having a Caesarean section and neonatal complications prevented mothers from breastfeeding their infants during the hospital stay. Work from this thesis will contribute to the efforts of tackling AMR in a LMIC, specifically in Viet Nam where there is extensive exposure to antimicrobials and sustained exposure to enteric pathogens.

Subjects/Keywords: Antimicrobial resistance; Diarrhoea in children

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APA (6^th Edition):

Le, N. T. Q. (2018). Diarrhoeal disease in children under five years of age in an urban community in Viet Nam. (Doctoral Dissertation). University of Oxford. Retrieved from http://ora.ox.ac.uk/objects/uuid:438b4e93-1c55-4e1d-acc2-b425ff7402ef ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.780685

Chicago Manual of Style (16^th Edition):

Le, Nhi Thi Quynh. “Diarrhoeal disease in children under five years of age in an urban community in Viet Nam.” 2018. Doctoral Dissertation, University of Oxford. Accessed January 16, 2021. http://ora.ox.ac.uk/objects/uuid:438b4e93-1c55-4e1d-acc2-b425ff7402ef ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.780685.

MLA Handbook (7^th Edition):

Le, Nhi Thi Quynh. “Diarrhoeal disease in children under five years of age in an urban community in Viet Nam.” 2018. Web. 16 Jan 2021.

Vancouver:

Le NTQ. Diarrhoeal disease in children under five years of age in an urban community in Viet Nam. [Internet] [Doctoral dissertation]. University of Oxford; 2018. [cited 2021 Jan 16]. Available from: http://ora.ox.ac.uk/objects/uuid:438b4e93-1c55-4e1d-acc2-b425ff7402ef ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.780685.

Council of Science Editors:

Le NTQ. Diarrhoeal disease in children under five years of age in an urban community in Viet Nam. [Doctoral Dissertation]. University of Oxford; 2018. Available from: http://ora.ox.ac.uk/objects/uuid:438b4e93-1c55-4e1d-acc2-b425ff7402ef ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.780685

12. Hau, Samantha Jean. Genetic and phenotypic characterization of livestock associated methicillin resistant Staphylococcus aureus sequence type (ST) 5 in comparison with clinical ST5 isolates from humans.

Degree: 2017, Iowa State University

URL: https://lib.dr.iastate.edu/etd/16143

► Staphylococcus aureus is a commensal and pathogen of humans and other animals. Disease with S. aureus is complicated by dissemination of antimicrobial resistance, including methicillin… (more)

▼ Staphylococcus aureus is a commensal and pathogen of humans and other animals. Disease with S. aureus is complicated by dissemination of antimicrobial resistance, including methicillin resistance. Methicillin resistant S. aureus (MRSA) is a significant burden on the health care industry (HA-MRSA); however, in recent years, public health concern has arisen from isolates harbored in the community (CA-MRSA) and livestock species (LA-MRSA). Concerns with LA-MRSA isolates are the direct impact of infection with livestock isolates and indirect impacts of genetic transfer of virulence or antimicrobial resistance genes from LA-MRSA isolates. The prototypical LA-MRSA strain, sequence type (ST) 398, is considered less virulent than HA- and CA-MRSA isolates. Reduced virulence of LA-MRSA ST398 isolates is attributed to loss of human specific virulence factors and reduced colonization and transmission in humans. While LA-MRSA ST398 isolates are common in European swine, LA-MRSA isolates in the United States are diverse including ST398, ST9, and ST5. LA-MRSA ST5 elevated public health concerns, because, unlike MRSA ST398 and ST9, MRSA ST5 is a globally disseminated and highly pathogenic lineage. To better understand direct and indirect impact of swine associated LA-MRSA ST5, this thesis investigated the genetics of swine associated and clinical MRSA ST5 isolates. Phylogenetic analysis revealed LA-MRSA ST5 isolates are genetically distinct from clinical MRSA ST5 isolates, which was confirmed by differences in virulence and antimicrobial resistance genes harbored on mobile genetic elements. LA-MRSA ST5 isolates lacked immune evasion genes harbored by the β-hemolysin converting bacteriophage and resistance genes differed between swine associated and clinical MRSA ST5 isolates, which indicated genetic exchange was unlikely between the screened populations. Resistance genes were consistent with selective pressures from antimicrobial use in the swine industry and hospital environment. Finally, swine associated and clinical MRSA ST5 isolates adhered equivalently to human keratinocytes, although LA-MRSA ST5 isolates lacked virulence factors contributing to colonization. These results indicate the isolates screened were distinct with no evidence of mobile genetic element transfer between subsets. The virulence of LA-MRSA ST5 isolates is expected to be reduced as compared to clinical MRSA ST5 isolates due to the absence of genes that contribute to disease in humans.

Subjects/Keywords: antimicrobial resistance; MRSA; swine; Microbiology

10 more images…

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APA (6^th Edition):

Hau, S. J. (2017). Genetic and phenotypic characterization of livestock associated methicillin resistant Staphylococcus aureus sequence type (ST) 5 in comparison with clinical ST5 isolates from humans. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/16143

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Hau, Samantha Jean. “Genetic and phenotypic characterization of livestock associated methicillin resistant Staphylococcus aureus sequence type (ST) 5 in comparison with clinical ST5 isolates from humans.” 2017. Thesis, Iowa State University. Accessed January 16, 2021. https://lib.dr.iastate.edu/etd/16143.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Hau, Samantha Jean. “Genetic and phenotypic characterization of livestock associated methicillin resistant Staphylococcus aureus sequence type (ST) 5 in comparison with clinical ST5 isolates from humans.” 2017. Web. 16 Jan 2021.

Vancouver:

Hau SJ. Genetic and phenotypic characterization of livestock associated methicillin resistant Staphylococcus aureus sequence type (ST) 5 in comparison with clinical ST5 isolates from humans. [Internet] [Thesis]. Iowa State University; 2017. [cited 2021 Jan 16]. Available from: https://lib.dr.iastate.edu/etd/16143.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Hau SJ. Genetic and phenotypic characterization of livestock associated methicillin resistant Staphylococcus aureus sequence type (ST) 5 in comparison with clinical ST5 isolates from humans. [Thesis]. Iowa State University; 2017. Available from: https://lib.dr.iastate.edu/etd/16143

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Manitoba

13. Davedow, Taylor. Investigation of an in-feed reduction of tylosin on the prevalence and severity of liver abscesses, antimicrobial resistant enterococci and productivity in feedlot cattle.

Degree: Food and Human Nutritional Sciences, 2019, University of Manitoba

URL: http://hdl.handle.net/1993/34486

► The primary objective of this work was to assess alternative feeding strategies on liver abscesses, growth performance, carcass traits, and immune responses in beef cattle… (more)

▼ The primary objective of this work was to assess alternative feeding strategies on liver abscesses, growth performance, carcass traits, and immune responses in beef cattle as well as to characterize antimicrobial resistance in enterococci isolated from cattle feces. In the first study, cattle (n = 90) were randomly assigned to 6 treatments (n = 15/treatment): 1) control, 2) low (12 g Saccharomyces cerevisiae fermentation product (SCFP) •steer-1•d-1), 3) medium (15 g SCFP•steer-1•d-1), 4) high SCFP (18 g SCFP•steer-1•d-1), 5) encapsulated SCFP (eXPC; 7 g XPC•steer-1•d-1), and 6) antibiotics (ANT; 330 mg monensin + 110 mg tylosin•steer-1•d-1). In the second study, cattle (n = 7576; ~ 253 animals/pen, 10 replicate pens per treatment) were randomized to 3 treatments: tylosin phosphate (11 ppm) in-feed 1) for the first 125 days on feed (DOF) (FIRST-78%), 2) for DOF 41 to 161 (LAST-75%), or 3) the entire feeding period (CON; day 0 to 161). Increasing SCFP tended (P < 0.09) to linearly increase feed efficiency. Average daily gain (ADG) tended (P < 0.10) to be greater in steers supplemented with eXPC than control. The percentage of erythromycin resistant (EryR) and erythromycin + tetracycline resistant enterococci was greater (P < 0.05) with ANT than control, SCFP and eXPC, while tetracycline resistant enterococci was not affected. Isolates were most frequently resistant to tylosin (86%), erythromycin (84%) and doxycycline (31%). Macrolide resistant isolates harbored primarily erm(B), msrC and tetracycline resistant isolates tet(L), tet(M), tet(O) genes. Cattle administered tylosin for a shorter duration had a greater risk of severe liver abscesses compared to controls; but there was no difference in risk of total liver abscesses, growth performance, carcass traits, morbidity or mortality. The proportion of EryR enterococci increased in all treatments over the feeding period. These studies support the potential to feed SCFP, eXPC or tylosin for a reduced duration as an alternative to the continuous administration of tylosin. This study emphasizes the importance of continued research into feeding regimens that promote antimicrobial stewardship, while maintaining the productivity and health of feedlot cattle. Advisors/Committee Members: Narvaez-Bravo, Claudia (Food and Human Nutritional Sciences), House, James (Food and Human Nutritional Sciences) (examiningcommittee), Yang, Chengbo (Animal Science) (examiningcommittee).

Subjects/Keywords: Tylosin; Antimicrobial; Cattle; Resistance; Beef

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APA (6^th Edition):

Davedow, T. (2019). Investigation of an in-feed reduction of tylosin on the prevalence and severity of liver abscesses, antimicrobial resistant enterococci and productivity in feedlot cattle. (Masters Thesis). University of Manitoba. Retrieved from http://hdl.handle.net/1993/34486

Chicago Manual of Style (16^th Edition):

Davedow, Taylor. “Investigation of an in-feed reduction of tylosin on the prevalence and severity of liver abscesses, antimicrobial resistant enterococci and productivity in feedlot cattle.” 2019. Masters Thesis, University of Manitoba. Accessed January 16, 2021. http://hdl.handle.net/1993/34486.

MLA Handbook (7^th Edition):

Davedow, Taylor. “Investigation of an in-feed reduction of tylosin on the prevalence and severity of liver abscesses, antimicrobial resistant enterococci and productivity in feedlot cattle.” 2019. Web. 16 Jan 2021.

Vancouver:

Davedow T. Investigation of an in-feed reduction of tylosin on the prevalence and severity of liver abscesses, antimicrobial resistant enterococci and productivity in feedlot cattle. [Internet] [Masters thesis]. University of Manitoba; 2019. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/1993/34486.

Council of Science Editors:

Davedow T. Investigation of an in-feed reduction of tylosin on the prevalence and severity of liver abscesses, antimicrobial resistant enterococci and productivity in feedlot cattle. [Masters Thesis]. University of Manitoba; 2019. Available from: http://hdl.handle.net/1993/34486

University of Manitoba

14. Cartwright, Nicola Helen. Examination of cationic antimicrobial tolerance in Escherichia coli to identify phenotypic and genotypic adaptations.

Degree: Medical Microbiology and Infectious Diseases, 2019, University of Manitoba

URL: http://hdl.handle.net/1993/34414

► Cationic antimicrobial (CA) agents describe a variety of positively charged antimicrobials that are widely used in many clinical, agricultural and industrial facilities to disinfect and… (more)

▼ Cationic antimicrobial (CA) agents describe a variety of positively charged antimicrobials that are widely used in many clinical, agricultural and industrial facilities to disinfect and prevent microbial growth. Increased tolerance to CAs by Gram-negative bacteria is a growing problem because CA tolerant bacteria frequently confer therapeutic antimicrobial cross-resistance. Previous studies have shown that CA tolerant bacteria frequently exhibit alterations in lipid modification pathways, up-regulation of efflux pumps and porins as a mechanism of tolerance but these changes have yet to be consistently identified in experiments containing the same species or strain exposed to different CAs. In this thesis, E. coli K12 was adapted to increasing concentrations of CAs, specifically, benzalkonium chloride, cetrimide bromide, chlorhexidine hydrochloride and colistin sulphate that belong to different antimicrobial classes to determine phenotypic and genotypic changes over 20-40 sub-cultures. It was revealed that CAs belonging to similar classes had similar growth phenotypes, antimicrobial cross-resistance and genotypic alterations. Experiments exploring the stability of CA-tolerant phenotypes when CA selection is removed over a 10-day period among revealed a dependence on previous CA exposure. Genotypic analysis involved identification of repeatedly identified single nucleotide variants (SNVs) in lipopolysaccharide biosynthesis pathways, antimicrobial transcriptional regulators, transposable elements, and to a lesser extent in efflux pump genes. This study suggests that CA adaptation may be dependent upon how each CA specifically disrupts the cell membrane, since each CA disrupts the membrane at potentially different outer membrane targets. It also reveals new insights and genetic markers associated with CA tolerance. Advisors/Committee Members: Bay, Denice (Medical Microbiology and Infectious Diseases), McClarty, Grant (Medical Microbiology and Infectious Diseases).

Subjects/Keywords: Cationic; Antimicrobial resistance; Escherichia coli

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APA (6^th Edition):

Cartwright, N. H. (2019). Examination of cationic antimicrobial tolerance in Escherichia coli to identify phenotypic and genotypic adaptations. (Masters Thesis). University of Manitoba. Retrieved from http://hdl.handle.net/1993/34414

Chicago Manual of Style (16^th Edition):

Cartwright, Nicola Helen. “Examination of cationic antimicrobial tolerance in Escherichia coli to identify phenotypic and genotypic adaptations.” 2019. Masters Thesis, University of Manitoba. Accessed January 16, 2021. http://hdl.handle.net/1993/34414.

MLA Handbook (7^th Edition):

Cartwright, Nicola Helen. “Examination of cationic antimicrobial tolerance in Escherichia coli to identify phenotypic and genotypic adaptations.” 2019. Web. 16 Jan 2021.

Vancouver:

Cartwright NH. Examination of cationic antimicrobial tolerance in Escherichia coli to identify phenotypic and genotypic adaptations. [Internet] [Masters thesis]. University of Manitoba; 2019. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/1993/34414.

Council of Science Editors:

Cartwright NH. Examination of cationic antimicrobial tolerance in Escherichia coli to identify phenotypic and genotypic adaptations. [Masters Thesis]. University of Manitoba; 2019. Available from: http://hdl.handle.net/1993/34414

IUPUI

15. Trombley, Michael Patrick. Phosphoethanolamine transferases in Haemophilus ducreyi modify lipid A and contribute to human defensin resistance.

Degree: 2015, IUPUI

URL: http://hdl.handle.net/1805/7915

►

Indiana University-Purdue University Indianapolis (IUPUI)

Haemophilus ducreyi resists the cytotoxic effects of human antimicrobial peptides (APs), including α-defensins, β-defensins, and the cathelicidin LL-37. Resistance to… (more)

▼

Indiana University-Purdue University Indianapolis (IUPUI)

Haemophilus ducreyi resists the cytotoxic effects of human antimicrobial peptides (APs), including α-defensins, β-defensins, and the cathelicidin LL-37. Resistance to LL-37, mediated by the sensitive to antimicrobial peptide (Sap) transporter, is required for H. ducreyi virulence in humans. Cationic APs are attracted to the negatively charged bacterial cell surface. In other gram-negative bacteria, modification of lipopolysaccharide or lipooligosaccharide (LOS) by the addition of positively charged moieties, such as phosphoethanolamine (PEA), confers AP resistance by means of electrostatic repulsion. H. ducreyi LOS has PEA modifications at two sites, and we identified three genes (lptA, ptdA, and ptdB) in H. ducreyi with homology to a family of bacterial PEA transferases. We generated non-polar, unmarked mutants with deletions in one, two, or all three putative PEA transferase genes. Mutants with deletions in two PEA transferase genes were significantly more susceptible to β-defensins, and the triple mutant was significantly more susceptible to both α- and β-defensins, but not LL-37; complementation of all three genes restored parental levels of AP resistance. Deletion of all three PEA transferase genes also resulted in a significant increase in the negativity of the mutant cell surface, suggesting these three genes contribute to the addition of positively charged moieties on the cell surface. Mass spectrometric analysis revealed that LptA was required for PEA modification of lipid A; PtdtA and PtdB did not affect PEA modification of LOS. In human inoculation experiments, the triple mutant was as virulent as its parent strain. While this is the first identified mechanism of resistance to α-defensins in H. ducreyi, our in vivo data suggest that resistance to cathelicidin may be more important than defensin resistance to H. ducreyi pathogenesis.

Advisors/Committee Members: Bauer, Margaret E..

Subjects/Keywords: Phosphoethanolamine Transferase; Antimicrobial Peptide Resistance

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APA (6^th Edition):

Trombley, M. P. (2015). Phosphoethanolamine transferases in Haemophilus ducreyi modify lipid A and contribute to human defensin resistance. (Thesis). IUPUI. Retrieved from http://hdl.handle.net/1805/7915

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Trombley, Michael Patrick. “Phosphoethanolamine transferases in Haemophilus ducreyi modify lipid A and contribute to human defensin resistance.” 2015. Thesis, IUPUI. Accessed January 16, 2021. http://hdl.handle.net/1805/7915.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Trombley, Michael Patrick. “Phosphoethanolamine transferases in Haemophilus ducreyi modify lipid A and contribute to human defensin resistance.” 2015. Web. 16 Jan 2021.

Vancouver:

Trombley MP. Phosphoethanolamine transferases in Haemophilus ducreyi modify lipid A and contribute to human defensin resistance. [Internet] [Thesis]. IUPUI; 2015. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/1805/7915.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Trombley MP. Phosphoethanolamine transferases in Haemophilus ducreyi modify lipid A and contribute to human defensin resistance. [Thesis]. IUPUI; 2015. Available from: http://hdl.handle.net/1805/7915

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

16. Muligisa-Muonga, Elizabeth. Characterization of Antimicrobial Resistant Salmonella and Escherichia Coli in retail Broiler Chickens in Lusaka province of Zambia.

Degree: 2019, University of Zimbabwe

URL: http://dspace.unza.zm/handle/123456789/6531

► The steady increase in the demand for poultry in Zambia and the world over has put a strain on poultry producers leading to the introduction… (more)

▼ The steady increase in the demand for poultry in Zambia and the world over has put a strain on poultry producers leading to the introduction of new practices such as the use of antibiotics in order to boost production. However, in many resource poor countries, the use of these antibiotics is often not monitored. When antibiotics are misused it can result in the emergence of antibiotic resistance in organisms that could find their way into poultry meat such as Salmonella and Escherichia coli (E. coli). These organisms, as well as others, that could be found in poultry meat, form a reservoir of Antimicrobial Resistant Genes that can be spread from one bacterium to another through horizontal gene transfer, whether pathogenic, commensal or environmental in nature. This spread is facilitated by cross-contamination of the poultry meat when in contact with other surfaces or products. A cross-sectional study was undertaken at the retail level in four districts of Lusaka province (Lusaka, Chilanga, Chongwe and Kafue) in order to determine the proportion of antimicrobial resistant Salmonella and E. coli from retail broiler chickens and to determine the genes that confer the resistance. Sampling was done between January and May 2018. A total of 250 whole broiler carcasses were purchased from 26 open markets (n=134) and 37 supermarkets (n=116). An open market was defined as an unrestricted competitive market in which any buyer and seller is free to participate, while a supermarket was defined as a self-service shop offering a wide variety of food and household products organized into aisles. Upon purchase, all samples were transported in a cooler box containing ice packs to the UNZA Veterinary Public Health Laboratory. Laboratory isolation included a whole carcass rinse in buffered peptone water (Oxoid), pre-enrichment and subsequent incubation at 37OC overnight. Ten microliter (10µL) of the incubated broth was then transferred to MacConkey agar (Oxoid UK) for E. coli isolation while 1ml was also transferred to Rappaport Vassiliadis (Oxoid UK) and later subcultured on Xylose-Lysine Deoxycholate agar (Oxoid UK) for isolation of Salmonella. Biochemical tests were performed on all suspected isolates using Analytical Profile Index (API 20E) (Biomerieux®). Further identification of the isolates was done using 16S rRNA sequencing for bacteria and Antimicrobial susceptibility tests were performed using the Kirby Bauer disk diffusion technique using a panel of 10 different antibiotics. The panel of antibiotics comprised of Ampicillin (10µg), Amoxicillin/Clavulanic acid (30µg), Imipenem (10µg), Nalidixic acid (30µg), Ciprofloxacin (5µg), Trimethoprim/Sulfamethoxazole (25µg), Colistin (10µg), Chloramphenicol (30µg), Tetracycline (30µg) and Cefotaxime (30µg). Analysis of the disk diffusion results was done using WHONET 2018 software. A total of 148 E. coli isolates were identified and subjected to antimicrobial susceptibility testing. Fifty three percent (53%) (n=79) of the isolates were from Open markets while 47% (n=69) were from…

Subjects/Keywords: Antimicrobial resistance; Poultry, Zambia

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APA (6^th Edition):

Muligisa-Muonga, E. (2019). Characterization of Antimicrobial Resistant Salmonella and Escherichia Coli in retail Broiler Chickens in Lusaka province of Zambia. (Thesis). University of Zimbabwe. Retrieved from http://dspace.unza.zm/handle/123456789/6531

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Muligisa-Muonga, Elizabeth. “Characterization of Antimicrobial Resistant Salmonella and Escherichia Coli in retail Broiler Chickens in Lusaka province of Zambia.” 2019. Thesis, University of Zimbabwe. Accessed January 16, 2021. http://dspace.unza.zm/handle/123456789/6531.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Muligisa-Muonga, Elizabeth. “Characterization of Antimicrobial Resistant Salmonella and Escherichia Coli in retail Broiler Chickens in Lusaka province of Zambia.” 2019. Web. 16 Jan 2021.

Vancouver:

Muligisa-Muonga E. Characterization of Antimicrobial Resistant Salmonella and Escherichia Coli in retail Broiler Chickens in Lusaka province of Zambia. [Internet] [Thesis]. University of Zimbabwe; 2019. [cited 2021 Jan 16]. Available from: http://dspace.unza.zm/handle/123456789/6531.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Muligisa-Muonga E. Characterization of Antimicrobial Resistant Salmonella and Escherichia Coli in retail Broiler Chickens in Lusaka province of Zambia. [Thesis]. University of Zimbabwe; 2019. Available from: http://dspace.unza.zm/handle/123456789/6531

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Waterloo

17. Couperus, Nathanael. Estimation and Occurrence of Select Antimicrobials in the Grand River Watershed.

Degree: 2015, University of Waterloo

URL: http://hdl.handle.net/10012/9051

► Antimicrobials are pharmaceutically active compounds that destroy or inhibit the growth of bacteria, fungi, protozoa, or viruses. This diverse group of compounds, used in both… (more)

▼ Antimicrobials are pharmaceutically active compounds that destroy or inhibit the growth of bacteria, fungi, protozoa, or viruses. This diverse group of compounds, used in both humans and livestock, are increasingly being detected in the environment, especially in soil and aquatic ecosystems. Their widespread environmental occurrence is being linked to the potential development of resistance traits in microorganisms, which is a serious threat to global health. Quantifying this health risk is difficult due to the lack of available data on the consumption of antimicrobials, as well as the varying regulations on their use and distribution. Further, the environmental fate and occurrence of these chemicals in watersheds is complex and poorly understood. The current research aims to address this knowledge gap by examining the occurrence and distribution of select antimicrobials in a watershed through modeling and empirical data collection (survey). It achieves this goal by addressing the following objectives: (1) to develop a mass load model for estimating the residual concentrations of veterinary antimicrobials; and (2) evaluate the occurrence and sources of select antimicrobials in surface waters. The Grand River Watershed, a mixed-use watershed in Southern Ontario, Canada, was selected as the study site. The mass load model was used to estimate the residual concentrations of four veterinary antimicrobials (lincomycin, monensin, oxytetracycline, and sulfamethazine) in the soil and water matrices. Predicted antimicrobial concentrations ranged from 0.1 μg/kg (monensin and oxytetracycline) to 60 μg/kg in soil (sulfamethazine) and 37 pg/L (oxytetracycline) to 18 μg/L (sulfamethazine) in surface water. Estimated antimicrobial concentrations were highest in sub-basins with high livestock densities, with the highest predicted levels found in the Nith sub-basin where there is intensive livestock production. For the occurrence survey in the Grand River Watershed, triplicate water samples were collected from 27 sites in the main channel, one location each in five tributaries, and seven wastewater treatment plant (WWTP) effluents. Temporal sampling was also performed in six additional sites (four in an agricultural tributary and two in the main channel). The water samples were analyzed for five antimicrobials (sulfamethazine, sulfamethoxazole, trimethoprim, lincomycin, and monensin), and three chemical indicators (venlafaxine, ibuprofen, and atrazine). In the main channel, measured concentrations of target analytes exhibited an increasing trend from the headwaters to downstream towards the discharge point to Lake Erie. Peak concentrations measured in the river water were 98 ± 8.8 ng/L for antimicrobials (sulfamethazine) and 146 ± 67 ng/L for the indicators (ibuprofen). In the effluents, the highest measured concentrations were 355 ± 126 ng/L for sulfamethoxazole and 349 ± 11 ng/L for ibuprofen. Atrazine was found at low concentrations throughout the river samples but was not found in the wastewater effluents. Lincomycin was…

Subjects/Keywords: Antimicrobial; Antibiotic Resistance; Estimation Model

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APA (6^th Edition):

Couperus, N. (2015). Estimation and Occurrence of Select Antimicrobials in the Grand River Watershed. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/9051

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Couperus, Nathanael. “Estimation and Occurrence of Select Antimicrobials in the Grand River Watershed.” 2015. Thesis, University of Waterloo. Accessed January 16, 2021. http://hdl.handle.net/10012/9051.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Couperus, Nathanael. “Estimation and Occurrence of Select Antimicrobials in the Grand River Watershed.” 2015. Web. 16 Jan 2021.

Vancouver:

Couperus N. Estimation and Occurrence of Select Antimicrobials in the Grand River Watershed. [Internet] [Thesis]. University of Waterloo; 2015. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/10012/9051.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Couperus N. Estimation and Occurrence of Select Antimicrobials in the Grand River Watershed. [Thesis]. University of Waterloo; 2015. Available from: http://hdl.handle.net/10012/9051

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Kansas State University

18. Giok, Felicia Xiaofei. Antimicrobial resistance in direct-fed microbial preparations used in cattle.

Degree: MS, Department of Diagnostic Medicine/Pathobiology, 2016, Kansas State University

URL: http://hdl.handle.net/2097/32859

► The use of antimicrobials in animal feed has come under increasing scrutiny from the public and regulatory agencies. Direct-fed microbials (DFM) are considered valuable alternatives… (more)

▼ The use of antimicrobials in animal feed has come under increasing scrutiny from the public and regulatory agencies. Direct-fed microbials (DFM) are considered valuable alternatives to antimicrobials in food animal nutrition. DFM are products containing live (viable microorganisms). Studies in Europe have reported antimicrobial resistance (AMR) in organisms used in DFM. This is of serious concern because of the potential for transferring resistance to pathogenic bacteria in the gut. The aim of the present study is to characterize phenotypic and genotypic AMR profiles for 20 different antimicrobials in bacterial strains isolated from 10 commercially available DFM used in. Two antimicrobial susceptibility testing methods, disc diffusion and broth micro-dilution based assay were performed. Enterococcus faecium isolates showed resistance towards metronidazole (n=9/9) with a MIC of > 32 μg/mL, erythromycin (n=5/9) with a MIC of ≥ 8 μg/mL, ciprofloxacin (n=2/9) with a MIC ≥ 4 μg/mL, ceftriaxone (n=6/9) with a MIC ≥ 0.25 μg/mL, rifampin (n=8/9) with a MIC of > 4 μg/mL, trimethoprim/sulfamethoxazole (n=4/9) with a MIC ≥ 1 μg/mL and clindamycin (n=5/9) with a MIC of > 0.5 μg/mL. A Propionibacterium freudenreichii isolate showed resistance towards kanamycin with a MIC of > 64 μg/mL. The same strain also had a MIC of 16 μg/mL for levofloxacin. Two Lactobacillus acidophilus were resistant to vancomycin (n=2/6) with a MIC ≥ 32 μg/mL. All the Lactobacillus species including L. acidophilus (n=6), L. casei (n=4) and L. plantarum (n=2) were resistant to metronidazole, MIC > 32 μg/mL. Two strains of Bacillus subtilis showed resistance to clindamycin, with an MIC of 4 μg/mL and erythromycin with an MIC of > 8 μg/mL, and one strain had no zone of inhibition for metronidazole (MIC > 32 μg/mL). Microarray analysis revealed resistance genes in E. faecium strains of 3 different DFM, including aminoglycoside resistance genes, ant(4’)-Ia, erythromycin resistance genes, ere(A2) and ermB, tetracycline resistance genes, tet39, tet31, tetK and tetC, and beta-lactam resistance gene, pbp5. Conjugation with filter mating showed erythromycin resistance gene transfer, msrC gene, from donor strains to a recipient strain (E. faecium 45-24). These studies show that AMR is prevalent among bacterial strains used as DFM in the cattle industry in the U.S., justifying further characterization, detection and observation of transferable antibiotic resistance between the same genus. . Advisors/Committee Members: Sanjeev Narayanan.

Subjects/Keywords: Antimicrobial Resistance; Direct-Fed Microbial

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APA (6^th Edition):

Giok, F. X. (2016). Antimicrobial resistance in direct-fed microbial preparations used in cattle. (Masters Thesis). Kansas State University. Retrieved from http://hdl.handle.net/2097/32859

Chicago Manual of Style (16^th Edition):

Giok, Felicia Xiaofei. “Antimicrobial resistance in direct-fed microbial preparations used in cattle.” 2016. Masters Thesis, Kansas State University. Accessed January 16, 2021. http://hdl.handle.net/2097/32859.

MLA Handbook (7^th Edition):

Giok, Felicia Xiaofei. “Antimicrobial resistance in direct-fed microbial preparations used in cattle.” 2016. Web. 16 Jan 2021.

Vancouver:

Giok FX. Antimicrobial resistance in direct-fed microbial preparations used in cattle. [Internet] [Masters thesis]. Kansas State University; 2016. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/2097/32859.

Council of Science Editors:

Giok FX. Antimicrobial resistance in direct-fed microbial preparations used in cattle. [Masters Thesis]. Kansas State University; 2016. Available from: http://hdl.handle.net/2097/32859

University of Guelph

19. Arndt, Emily Rose. An investigation into distribution of serotypes and antimicrobial resistance patterns of Streptococcus suis isolates from clinical cases and healthy carrier pigs.

Degree: MS, Department of Population Medicine, 2017, University of Guelph

URL: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/10309

► The distribution of Streptococcus suis serotypes and antimicrobial resistance patterns in clinical cases and healthy carrier pigs was investigated. Isolates were confirmed as S. suis… (more)

Subjects/Keywords: Streptococcus suis; pigs; antimicrobial resistance

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APA (6^th Edition):

Arndt, E. R. (2017). An investigation into distribution of serotypes and antimicrobial resistance patterns of Streptococcus suis isolates from clinical cases and healthy carrier pigs. (Masters Thesis). University of Guelph. Retrieved from https://atrium.lib.uoguelph.ca/xmlui/handle/10214/10309

Chicago Manual of Style (16^th Edition):

Arndt, Emily Rose. “An investigation into distribution of serotypes and antimicrobial resistance patterns of Streptococcus suis isolates from clinical cases and healthy carrier pigs.” 2017. Masters Thesis, University of Guelph. Accessed January 16, 2021. https://atrium.lib.uoguelph.ca/xmlui/handle/10214/10309.

MLA Handbook (7^th Edition):

Arndt, Emily Rose. “An investigation into distribution of serotypes and antimicrobial resistance patterns of Streptococcus suis isolates from clinical cases and healthy carrier pigs.” 2017. Web. 16 Jan 2021.

Vancouver:

Arndt ER. An investigation into distribution of serotypes and antimicrobial resistance patterns of Streptococcus suis isolates from clinical cases and healthy carrier pigs. [Internet] [Masters thesis]. University of Guelph; 2017. [cited 2021 Jan 16]. Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/10309.

Council of Science Editors:

Arndt ER. An investigation into distribution of serotypes and antimicrobial resistance patterns of Streptococcus suis isolates from clinical cases and healthy carrier pigs. [Masters Thesis]. University of Guelph; 2017. Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/10309

University of New South Wales

20. Kuppusamy, Rajesh. Design, synthesis and mode of action of short biphenyl and anthranilamide cationic peptidomimetics.

Degree: Chemistry, 2019, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/66866

► Antimicrobial resistance is a major worldwide threat to public health and there is an urgent need for the development of novel antibacterial agents. This research… (more)

▼ Antimicrobial resistance is a major worldwide threat to public health and there is an urgent need for the development of novel antibacterial agents. This research project focused on the development of short cationic peptidomimetics that employ 3'-amino-[1, 1 '-biphenyl)-3-carboxylic acid and anthranilic acidbackbones segregated by hydrophobic and cationic groups. The biphenyl peptidomimetic compounds showed that simple diaminoethanes and their respective guanidine cationic groups were sufficient to mimic lysine and arginine amino acids of natural antimicrobial peptides. The biphenyl backbone was important for antibacterial activity and tryptophan was important for bacterial cell membrane permeability. The most active compound showed good minimum inhibitory concentrations (MIC) against S. aureus (15.6 μM) and E.coli (7.8 μM) but was inactive against P. aeruginosa strain PA01. Based on these results, anthranilamide derivatives with tryptophan and simple amine cationic groups were developed. The anthranilamide peptidomimetic compounds showed that the guanidine group was important for good antibacterial activity against S. aureus (3.9 μM), E.coli (15.6 μM), and these compounds had low cytotoxicity (>100 μM). Active compounds disrupted 75% of established S. aureus biofilms. Biphenyl could be used as an alternative to naphthoyl groups to give hydrophobic groups to the mimetics. Increasing the net charge by adding lysine decreased antibacterial activity compared to compounds containing simple amine groups but improved the compound's cytotoxicity.Various alkyl-substituted guanidine compounds were investigated. Increasing the lipophilicity (adding alkyl groups) at the guanidine residues decreased antibacterial activity. Increasing the cationicity increased antibacterial activity against P. aeruginosa. The most active compound showed broad-spectrumantibacterial activity of against S. aureus (2.0 μM), E.coli (7.8 μM), and P. aeruginosa (32.0 μM). The active compounds at 4.0-8.0 μM showed significant disruption (55-77%) of preformed S. aureus biofilms and one compound at 15.6 μM disrupted 45% of E.coli biofilms. Peptidomimetics are promising future antibiotics. These compounds can potentially circumvent current antimicrobial resistance that is generated when bacteria produce biofilms. Advisors/Committee Members: Kumar, Naresh, Chemistry, Faculty of Science, UNSW, StC Black, David, Chemistry, Faculty of Science, UNSW.

Subjects/Keywords: Biofilms; Cationic peptidomimetics; Antimicrobial resistance

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APA (6^th Edition):

Kuppusamy, R. (2019). Design, synthesis and mode of action of short biphenyl and anthranilamide cationic peptidomimetics. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/66866

Chicago Manual of Style (16^th Edition):

Kuppusamy, Rajesh. “Design, synthesis and mode of action of short biphenyl and anthranilamide cationic peptidomimetics.” 2019. Doctoral Dissertation, University of New South Wales. Accessed January 16, 2021. http://handle.unsw.edu.au/1959.4/66866.

MLA Handbook (7^th Edition):

Kuppusamy, Rajesh. “Design, synthesis and mode of action of short biphenyl and anthranilamide cationic peptidomimetics.” 2019. Web. 16 Jan 2021.

Vancouver:

Kuppusamy R. Design, synthesis and mode of action of short biphenyl and anthranilamide cationic peptidomimetics. [Internet] [Doctoral dissertation]. University of New South Wales; 2019. [cited 2021 Jan 16]. Available from: http://handle.unsw.edu.au/1959.4/66866.

Council of Science Editors:

Kuppusamy R. Design, synthesis and mode of action of short biphenyl and anthranilamide cationic peptidomimetics. [Doctoral Dissertation]. University of New South Wales; 2019. Available from: http://handle.unsw.edu.au/1959.4/66866

The Ohio State University

21. Mollenkopf, Dixie Francis. Epidemiology of ß-lactamase-producing Enterobacteriaceae in Humans and Livestock.

Degree: PhD, Comparative and Veterinary Medicine, 2017, The Ohio State University

URL: http://rave.ohiolink.edu/etdc/view?acc_num=osu1505147339870873

► Carbapenems have the broadest spectrum of the large ß-lactam antimicrobials and have been reserved as a “drug of last resort” against invasive Gram-positive and Gram-negative… (more)

▼ Carbapenems have the broadest spectrum of the large ß-lactam antimicrobials and have been reserved as a “drug of last resort” against invasive Gram-positive and Gram-negative human infections. The increasing prevalence of complicated MDR infections involving extended spectrum (ESßL) and AmpC ß-lactamases has triggered the increasing need for carbapenem use. The emergence of carbapenemase-producing Enterobactericeae was described as “the end of the antibiotic era” as these potential pathogens harbor highly-mobile genetic elements that confer resistance to our most critically important drugs.In the US, nontyphoidal Salmonella are a common foodborne zoonotic pathogen causing gastroenteritis. MDR invasive Salmonella infections mediated by ESßL or AmpC genotypes are more likely to require carbapenem therapy compared to susceptible infections. Of 571 isolates, we characterized 44 blaCMY-2-bearing Salmonella that resulted from 5,050 individual cattle fecal samples from 68 large (1,000+ head capacity) US feedlots participating in the NAHMS Beef Feedlot 2011 study, and assessed risk factors for blaCMY-2 carriage. Cultured without antimicrobial selection, the isolates represented eight serotypes and carried the blaCMY-2/IncA/C gene/plasmid combination with most expressing the penta-resistance (ACSSuT) phenotype. Cattle fed chlortetracycline in their diet and heavier weight cattle were less likely to carry Salmonella with blaCMY-2. In contrast, cattle fed the macrolide feed additive tylosin and cattle in pens with increasing numbers of dairy cattle were more likely to harbor blaCMY-bearing Salmonella. To determine the prevalence of foodborne resistance mechanisms, we screened human diarrheic stool samples submitted for Clostridium difficle culture from patients of The Ohio State University Wexner Medical Center (OSUWMC) to estimate the frequency of carriage of ESßL- and AmpC- as well as carbapenemase-producing enteric bacteria. The 692 deidentified samples received between July and December 2013 were cultured using selective media to detect the resistant phenotypes. Our selective culture yielded 184 isolates (26.6 %) with reduced susceptibility to cefotaxime. Of these, 46 (6.7%) samples harbored commensal isolates carrying the AmpC blaCMY. Another 21 (3.0%) samples produced isolates harboring the ESBL blaCTX-M: 19 carrying CTX-M-15 and 2 with CTX-M-27. Additionally, 13 samples (1.9 %) produced Enterobacteriaceae or Pseudomonas spp. resistant to carbapenems. Of these, whole genome sequencing identified a prominent CRE strain, sequence type ST258, K. pneumoniae harboring blaKPC-3 and a second K. pneumoniae carrying blaNDM-1 ST1602 which had not been previously reported. Reporting the first mobile carbapenemase, blaIMP-64 on an IncQ1 plasmid, in US livestock, we followed a cohort of 350+ pigs from late sow gestation to the final finishing phase in order to better understand the maintenance of this rare resistance genotype in a large farrow-to-finish swine operation. Environmental and fecal samples were collected during 8 visits… Advisors/Committee Members: Wittum, Thomas (Advisor).

Subjects/Keywords: Epidemiology; Antimicrobial resistance, Enterobacteriaceae, Carbapenemase

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APA (6^th Edition):

Mollenkopf, D. F. (2017). Epidemiology of ß-lactamase-producing Enterobacteriaceae in Humans and Livestock. (Doctoral Dissertation). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1505147339870873

Chicago Manual of Style (16^th Edition):

Mollenkopf, Dixie Francis. “Epidemiology of ß-lactamase-producing Enterobacteriaceae in Humans and Livestock.” 2017. Doctoral Dissertation, The Ohio State University. Accessed January 16, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1505147339870873.

MLA Handbook (7^th Edition):

Mollenkopf, Dixie Francis. “Epidemiology of ß-lactamase-producing Enterobacteriaceae in Humans and Livestock.” 2017. Web. 16 Jan 2021.

Vancouver:

Mollenkopf DF. Epidemiology of ß-lactamase-producing Enterobacteriaceae in Humans and Livestock. [Internet] [Doctoral dissertation]. The Ohio State University; 2017. [cited 2021 Jan 16]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1505147339870873.

Council of Science Editors:

Mollenkopf DF. Epidemiology of ß-lactamase-producing Enterobacteriaceae in Humans and Livestock. [Doctoral Dissertation]. The Ohio State University; 2017. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1505147339870873

22. Oppedijk, S.F. Identification, purification and elucidation of the mode of action of (novel) antimicrobial substances.

Degree: 2017, University Utrecht

URL: https://dspace.library.uu.nl/handle/1874/356787 ; URN:NBN:NL:UI:10-1874-356787 ; 1874/356787 ; urn:isbn:9789039368589 ; URN:NBN:NL:UI:10-1874-356787 ; https://dspace.library.uu.nl/handle/1874/356787

► Antibiotics are among the most frequently prescribed medications in current medicine, however there is an increasing resistance emerging against our current arsenal of antibiotics. Therefore,… (more)

▼ Antibiotics are among the most frequently prescribed medications in current medicine, however there is an increasing resistance emerging against our current arsenal of antibiotics. Therefore, it is important that we do research into antimicrobial substances that uniquely work on essential pathways to make it difficult for bacteria to develop resistance. One such specific targets is the peptidoglycan precursor lipid II. In Gram-positive bacteria, the peptidoglycan is readily available from the outside and this structure is essential for bacteria to withstand the pressure from their interior (sacculus). One novel antimicrobial compounds we study in this manuscript is derived from an extract from the fungus Talaromyces atroroseus that seems to specifically interact with lipid II. We furthermore showed that Laspartomycin C inhibits peptidoglycan biosynthesis by sequestering the bactoprenol lipid carrier of this same essential peptidoglycan component, showing that inhibition of this pathway does not only happen at the level of lipid II. Further studies described in this dissertation focus on a unique peptide called Pep5 of which up to now the exact mode of action is unknown. The high activity towards pathogens such as MRSA in nanomolar concentrations suggest that it works via an interaction with a similar specific target and makes to mode of action of this peptide highly interesting. We studied the effects of this peptide on the energy metabolism in susceptible bacteria with a metabolomics approach and used genetic sequencing on resistant bacteria to elucidate what changes in the genetic code resulted in resistance development to be able to better understand what pathway this peptide interferes in. The exact mode of action remains unknown, however the characteristics of the mode of action of this peptide are distinctly different compared to known antibiotic and might entail a novel way of developing novel antibiotics to combat resistant bacteria. Advisors/Committee Members: Killian, Antoinette, den Hertog, J., Breukink, Eefjan, Martin, Nathaniel.

Subjects/Keywords: Antimicrobial Resistance

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APA (6^th Edition):

Oppedijk, S. F. (2017). Identification, purification and elucidation of the mode of action of (novel) antimicrobial substances. (Doctoral Dissertation). University Utrecht. Retrieved from https://dspace.library.uu.nl/handle/1874/356787 ; URN:NBN:NL:UI:10-1874-356787 ; 1874/356787 ; urn:isbn:9789039368589 ; URN:NBN:NL:UI:10-1874-356787 ; https://dspace.library.uu.nl/handle/1874/356787

Chicago Manual of Style (16^th Edition):

Oppedijk, S F. “Identification, purification and elucidation of the mode of action of (novel) antimicrobial substances.” 2017. Doctoral Dissertation, University Utrecht. Accessed January 16, 2021. https://dspace.library.uu.nl/handle/1874/356787 ; URN:NBN:NL:UI:10-1874-356787 ; 1874/356787 ; urn:isbn:9789039368589 ; URN:NBN:NL:UI:10-1874-356787 ; https://dspace.library.uu.nl/handle/1874/356787.

MLA Handbook (7^th Edition):

Oppedijk, S F. “Identification, purification and elucidation of the mode of action of (novel) antimicrobial substances.” 2017. Web. 16 Jan 2021.

Vancouver:

Oppedijk SF. Identification, purification and elucidation of the mode of action of (novel) antimicrobial substances. [Internet] [Doctoral dissertation]. University Utrecht; 2017. [cited 2021 Jan 16]. Available from: https://dspace.library.uu.nl/handle/1874/356787 ; URN:NBN:NL:UI:10-1874-356787 ; 1874/356787 ; urn:isbn:9789039368589 ; URN:NBN:NL:UI:10-1874-356787 ; https://dspace.library.uu.nl/handle/1874/356787.

Council of Science Editors:

Oppedijk SF. Identification, purification and elucidation of the mode of action of (novel) antimicrobial substances. [Doctoral Dissertation]. University Utrecht; 2017. Available from: https://dspace.library.uu.nl/handle/1874/356787 ; URN:NBN:NL:UI:10-1874-356787 ; 1874/356787 ; urn:isbn:9789039368589 ; URN:NBN:NL:UI:10-1874-356787 ; https://dspace.library.uu.nl/handle/1874/356787

Colorado State University

23. Rovira Sanz, Pablo. Impact of antibiotic use on resistance in beef feedlot and dairy cattle.

Degree: PhD, Animal Sciences, 2017, Colorado State University

URL: http://hdl.handle.net/10217/183928

► In recent years, consumer demand for natural and organic foods has increased, partly due to concerns about the use of antimicrobials in food producing animals.… (more)

▼ In recent years, consumer demand for natural and organic foods has increased, partly due to concerns about the use of antimicrobials in food producing animals. The aim of this study was to evaluate antimicrobial resistance (AMR) in beef feedlot and dairy cattle raised without use of antibiotics compared to cattle raised in conventional (CONV) production. Three research projects were conducted to accomplish that general goal. In the first study, a conventional feedlot, natural feedlot, conventional dairy and organic dairy were visited to collect cattle feces, wastewater from lagoons and soil where the wastewater was applied. After DNA extraction, sequencing, and processing, metagenomic reads were aligned to reference databases for identification of antibiotic resistance genes (ARGs; i.e. the resistome) and bacteria (microbiome). Resistome composition was influenced by rearing method, cattle type, and type of sample. Most mechanisms of resistance affected by rearing method were enriched (P < 0.05) in conventional samples. Resistome differences were greatest for wastewater samples by rearing method but with contradictory results that suggested an impact of effluent management on wastewater resistome. Resistance to tetracycline and macrolide-lincosamide-streptogramin classes were more abundant in feces of feedlot cattle than in dairy cattle (P < 0.05); whereas resistance to beta-lactams was greatest in feces of dairy cattle (P < 0.05). Resistome and microbiome of feces differed (P < 0.05) between wastewater and soil samples. Results indicated that ARGs are widespread in beef feedlot and dairy cattle farms even in those with restricted antibiotic use. In the second study, feces from RWA (n=36) and CONV (n=36) cattle lots were recovered from colons at a commercial beef processing plant. Samples were equally distributed by month and production protocol over one year (3 samples/production protocol/month). After extracting DNA from individual samples, composite samples were prepared by mixing DNA from each lot into a single composite sample (N = 72) and sequencing the composites on an Illumina platform. Metagenomic reads were processed similarly to those in experiment 1for identification of ARGs and bacteria. Resistomes of CONV and RWA cattle were significantly different by season. In general, mechanisms conferring resistance to beta-lactams, tetracyclines, multi-drug and macrolides were more prevalent (P < 0.05) in feces from CONV colons than in RWA colons. In the third study, a systematic review and meta-analysis was performed to assess the relationship between antimicrobial use (AMU) and antimicrobial resistance (AMR) in feedlot cattle. After conducting a literature search and screening reported studies, 32 studies were selected for use that addressed AMR in Escherichia coli, Enterococcus, Salmonella, Campylobacter, and Mannheimia haemolytica. Overall, 60% (95% CI: 26% to 88%) of the observational studies and 50% (95% CI: 30% to 70%) of the controlled trials reported a positive association between AMU and AMR.… Advisors/Committee Members: Belk, Keith (advisor), Morley, Paul (committee member), Schmidt, John (committee member), Yang, Hua (committee member).

Subjects/Keywords: bacteria; metagenomics; antimicrobial resistance; resistance genes; cattle

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APA (6^th Edition):

Rovira Sanz, P. (2017). Impact of antibiotic use on resistance in beef feedlot and dairy cattle. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/183928

Chicago Manual of Style (16^th Edition):

Rovira Sanz, Pablo. “Impact of antibiotic use on resistance in beef feedlot and dairy cattle.” 2017. Doctoral Dissertation, Colorado State University. Accessed January 16, 2021. http://hdl.handle.net/10217/183928.

MLA Handbook (7^th Edition):

Rovira Sanz, Pablo. “Impact of antibiotic use on resistance in beef feedlot and dairy cattle.” 2017. Web. 16 Jan 2021.

Vancouver:

Rovira Sanz P. Impact of antibiotic use on resistance in beef feedlot and dairy cattle. [Internet] [Doctoral dissertation]. Colorado State University; 2017. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/10217/183928.

Council of Science Editors:

Rovira Sanz P. Impact of antibiotic use on resistance in beef feedlot and dairy cattle. [Doctoral Dissertation]. Colorado State University; 2017. Available from: http://hdl.handle.net/10217/183928

University of Cambridge

24. Rowe, Will. Antimicrobial resistance gene monitoring in aquatic environments.

Degree: PhD, 2016, University of Cambridge

URL: https://www.repository.cam.ac.uk/handle/1810/253755https://www.repository.cam.ac.uk/bitstream/1810/253755/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/253755/3/license_rdf ; https://www.repository.cam.ac.uk/bitstream/1810/253755/4/DISSERTATION.corrected.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/253755/5/DISSERTATION.corrected.pdf.jpg

► This dissertation documents the development of an environmental framework for monitoring antimicrobial resistance gene (ARG) dissemination in the aquatic environment. The work opens with a… (more)

▼ This dissertation documents the development of an environmental framework for monitoring antimicrobial resistance gene (ARG) dissemination in the aquatic environment. The work opens with a review of the relevant literature and outlines the importance of an environmental framework for monitoring ARG dissemination as part of antimicrobial resistance risk assessments. The ability to interrogate sequencing data quickly and easily for the presence of ARGs is crucial in order to facilitate their monitoring in the environment. As current laboratory methods for the detection and surveillance of antimicrobial resistant bacteria in the environment were limited in their effectiveness and scope, the dissertation begins by describing the design and implementation of a Search Engine for Antimicrobial Resistance (SEAR), a pipeline and web interface for detection of horizontally-acquired ARGs in raw sequencing data. The suitability of metagenomic methods for monitoring the ARG content of effluents from faecal sources was then assessed via a pilot study of a river catchment. Novel metagenomes generated from effluents entering the catchment were interrogated for ARGs. The relative abundance of ARGs in effluents were determined to be higher relative to the background environment, as were sequences relating to human and animal pathogens and mobile genetic elements. Thus, effluents were implicated in the dissemination of ARGs throughout the aquatic environment. To determine if ARGs were potentially in use in the environment, the expression of ARGs within effluents was then evaluated across a series of longitudinal samples through the use of metatranscriptomics, and the presence of potential environmental antimicrobial selection pressures was examined. This demonstrated that the abundance of ARGs, as well as antimicrobial usage at the effluent source, was correlated with the transcription of ARGs in aquatic environments. The work described in this dissertation has also found that horizontally transmitted ARGs were present in pathogenic endospore-forming bacteria commonly found across the aquatic environment, potentially providing a mechanism for ARG persistence in the environment. Finally, these findings were integrated into a universal framework for monitoring ARG dissemination in aquatic environments and used to highlight the developments required to incorporate this framework into future environmental ARG research and to facilitate antimicrobial resistance risk assessments.

Subjects/Keywords: Metagenomics; Antimicrobial resistance; Antibiotic resistance; Wastewater

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Rowe, W. (2016). Antimicrobial resistance gene monitoring in aquatic environments. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/253755https://www.repository.cam.ac.uk/bitstream/1810/253755/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/253755/3/license_rdf ; https://www.repository.cam.ac.uk/bitstream/1810/253755/4/DISSERTATION.corrected.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/253755/5/DISSERTATION.corrected.pdf.jpg

Chicago Manual of Style (16^th Edition):

Rowe, Will. “Antimicrobial resistance gene monitoring in aquatic environments.” 2016. Doctoral Dissertation, University of Cambridge. Accessed January 16, 2021. https://www.repository.cam.ac.uk/handle/1810/253755https://www.repository.cam.ac.uk/bitstream/1810/253755/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/253755/3/license_rdf ; https://www.repository.cam.ac.uk/bitstream/1810/253755/4/DISSERTATION.corrected.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/253755/5/DISSERTATION.corrected.pdf.jpg.

MLA Handbook (7^th Edition):

Rowe, Will. “Antimicrobial resistance gene monitoring in aquatic environments.” 2016. Web. 16 Jan 2021.

Vancouver:

Rowe W. Antimicrobial resistance gene monitoring in aquatic environments. [Internet] [Doctoral dissertation]. University of Cambridge; 2016. [cited 2021 Jan 16]. Available from: https://www.repository.cam.ac.uk/handle/1810/253755https://www.repository.cam.ac.uk/bitstream/1810/253755/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/253755/3/license_rdf ; https://www.repository.cam.ac.uk/bitstream/1810/253755/4/DISSERTATION.corrected.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/253755/5/DISSERTATION.corrected.pdf.jpg.

Council of Science Editors:

Rowe W. Antimicrobial resistance gene monitoring in aquatic environments. [Doctoral Dissertation]. University of Cambridge; 2016. Available from: https://www.repository.cam.ac.uk/handle/1810/253755https://www.repository.cam.ac.uk/bitstream/1810/253755/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/253755/3/license_rdf ; https://www.repository.cam.ac.uk/bitstream/1810/253755/4/DISSERTATION.corrected.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/253755/5/DISSERTATION.corrected.pdf.jpg

University of Cambridge

25. Rowe, Will. Antimicrobial resistance gene monitoring in aquatic environments.

Degree: PhD, 2016, University of Cambridge

URL: https://doi.org/10.17863/CAM.16362 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683707

► This dissertation documents the development of an environmental framework for monitoring antimicrobial resistance gene (ARG) dissemination in the aquatic environment. The work opens with a… (more)

▼ This dissertation documents the development of an environmental framework for monitoring antimicrobial resistance gene (ARG) dissemination in the aquatic environment. The work opens with a review of the relevant literature and outlines the importance of an environmental framework for monitoring ARG dissemination as part of antimicrobial resistance risk assessments. The ability to interrogate sequencing data quickly and easily for the presence of ARGs is crucial in order to facilitate their monitoring in the environment. As current laboratory methods for the detection and surveillance of antimicrobial resistant bacteria in the environment were limited in their effectiveness and scope, the dissertation begins by describing the design and implementation of a Search Engine for Antimicrobial Resistance (SEAR), a pipeline and web interface for detection of horizontally-acquired ARGs in raw sequencing data. The suitability of metagenomic methods for monitoring the ARG content of effluents from faecal sources was then assessed via a pilot study of a river catchment. Novel metagenomes generated from effluents entering the catchment were interrogated for ARGs. The relative abundance of ARGs in effluents were determined to be higher relative to the background environment, as were sequences relating to human and animal pathogens and mobile genetic elements. Thus, effluents were implicated in the dissemination of ARGs throughout the aquatic environment. To determine if ARGs were potentially in use in the environment, the expression of ARGs within effluents was then evaluated across a series of longitudinal samples through the use of metatranscriptomics, and the presence of potential environmental antimicrobial selection pressures was examined. This demonstrated that the abundance of ARGs, as well as antimicrobial usage at the effluent source, was correlated with the transcription of ARGs in aquatic environments. The work described in this dissertation has also found that horizontally transmitted ARGs were present in pathogenic endospore-forming bacteria commonly found across the aquatic environment, potentially providing a mechanism for ARG persistence in the environment. Finally, these findings were integrated into a universal framework for monitoring ARG dissemination in aquatic environments and used to highlight the developments required to incorporate this framework into future environmental ARG research and to facilitate antimicrobial resistance risk assessments.

Subjects/Keywords: 579; Metagenomics; Antimicrobial resistance; Antibiotic resistance; Wastewater

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Rowe, W. (2016). Antimicrobial resistance gene monitoring in aquatic environments. (Doctoral Dissertation). University of Cambridge. Retrieved from https://doi.org/10.17863/CAM.16362 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683707

Chicago Manual of Style (16^th Edition):

Rowe, Will. “Antimicrobial resistance gene monitoring in aquatic environments.” 2016. Doctoral Dissertation, University of Cambridge. Accessed January 16, 2021. https://doi.org/10.17863/CAM.16362 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683707.

MLA Handbook (7^th Edition):

Rowe, Will. “Antimicrobial resistance gene monitoring in aquatic environments.” 2016. Web. 16 Jan 2021.

Vancouver:

Rowe W. Antimicrobial resistance gene monitoring in aquatic environments. [Internet] [Doctoral dissertation]. University of Cambridge; 2016. [cited 2021 Jan 16]. Available from: https://doi.org/10.17863/CAM.16362 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683707.

Council of Science Editors:

Rowe W. Antimicrobial resistance gene monitoring in aquatic environments. [Doctoral Dissertation]. University of Cambridge; 2016. Available from: https://doi.org/10.17863/CAM.16362 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683707

Stellenbosch University

26. Berge, Simon Nicholas. Production and characterisation of analogues of the antimicrobial tyrocidine peptides with modified aromatic amino acid residues.

Degree: MSc, Biochemistry, 2018, Stellenbosch University

URL: http://hdl.handle.net/10019.1/103710

► ENGLISH ABSTRACT: With the approach of a post-antibiotic era in which the current arsenal of antibiotic compounds can no longer combat common bacterial infections, the… (more)

▼ ENGLISH ABSTRACT: With the approach of a post-antibiotic era in which the current arsenal of antibiotic compounds can no longer combat common bacterial infections, the search for novel compounds to fight against antimicrobial resistance is more important than ever. A group of forgotten antimicrobial peptides, termed the tyrocidines, have re-emerged as promising candidates for further development in clinical and industrial settings. These are basic, cyclic decapeptides, with the sequence cyclo(D-Phe1-L-Pro2-L-(Phe3/Trp3)-D-(Phe4/Trp4)-L-Asn5- L-Gln6-L-(Tyr7/Phe7/Trp7)-L-Val8-L-Orn9-L-Leu10), and are naturally synthesized, together with the neutral, linear pentadecapeptides, the gramicidins, by the soil bacterium Brevibacillus parabrevis. A multitude of structurally similar tyrocidines has been found in extracts of this organism. This arises due to the non-ribosomal, enzymatic, synthesis of these peptides in which certain domains within this multi-domain enzyme system have the ability to incorporate more than one kind of aromatic amino acid. The specific structural variations are at residue positions 3, 4 and 7 in the cyclic decapeptide. These structural variations produce tyrocidines with unique structure-activity relationships, imbuing them with activity against a wide variety of Grampositive bacteria and fungi. Activity against the malarial parasite, Plasmodium falciparum, has also been observed. This study aims to make use of the variability seen for incorporation of different aromatic amino acid residues, specifically of phenylalanine and tryptophan, to determine if non-natural derivatives of these amino acids can be incorporated, to biosynthesize novel tyrocidine, tryptocidine and phenycidine analogues (collectively termed the Trcs), with unique structureactivity relationships. The initial objective of this study was to characterise different available strains of the producer organism, to determine if there was a difference in the production profiles of Trcs by the producer organism. A clear difference was found between the Br. parabrevis 5618, 362, 10068 and 8185 strains in terms of their production profiles, with the 5618 showing a marked improvement in Trc analogues rich in tryptophan. In addition to strain-determined differences in production profiles, differences in production as a result of altered nutrient conditions, in the form of nitrogen, sulphate and carbon sources, added on top of a base media, were also investigated. This was initially done by growth rate analysis of the producer organisms under different conditions, and then followed up by small scale culture to determine the effect on production of Trcs. Altered productions in terms of biomass and extract mass were found, and to a lesser degree the Trc production profile. Urea appeared to have the most marked effect on Trc production, particularly for the 5618 strain. The next objective was to determine if the selected phenylalanine analogues 4-methylphenylalanine (4-MeF), 2-flouro-phenylalanine (2-FF) and… Advisors/Committee Members: Rautenbach, Marina, Stellenbosch University. Faculty of Science. Dept. of Biochemistry..

Subjects/Keywords: Antimicrobial peptides; Tyrocidines; Aromatic amino acids residues; UCTD; Antimicrobial resistance (AMR)

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Berge, S. N. (2018). Production and characterisation of analogues of the antimicrobial tyrocidine peptides with modified aromatic amino acid residues. (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/103710

Chicago Manual of Style (16^th Edition):

Berge, Simon Nicholas. “Production and characterisation of analogues of the antimicrobial tyrocidine peptides with modified aromatic amino acid residues.” 2018. Masters Thesis, Stellenbosch University. Accessed January 16, 2021. http://hdl.handle.net/10019.1/103710.

MLA Handbook (7^th Edition):

Berge, Simon Nicholas. “Production and characterisation of analogues of the antimicrobial tyrocidine peptides with modified aromatic amino acid residues.” 2018. Web. 16 Jan 2021.

Vancouver:

Berge SN. Production and characterisation of analogues of the antimicrobial tyrocidine peptides with modified aromatic amino acid residues. [Internet] [Masters thesis]. Stellenbosch University; 2018. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/10019.1/103710.

Council of Science Editors:

Berge SN. Production and characterisation of analogues of the antimicrobial tyrocidine peptides with modified aromatic amino acid residues. [Masters Thesis]. Stellenbosch University; 2018. Available from: http://hdl.handle.net/10019.1/103710

Colorado State University

27. Noyes, Noelle Robertson. Epidemiology and ecology of antimicrobial use and resistance in North American beef production systems, The.

Degree: PhD, Clinical Sciences, 2016, Colorado State University

URL: http://hdl.handle.net/10217/173328

► Antimicrobial resistance (AMR) is a critical public health issue (1), and analysis of historical Escherichia coli isolates reveals that AMR has been increasing steadily since… (more)

▼ Antimicrobial resistance (AMR) is a critical public health issue (1), and analysis of historical Escherichia coli isolates reveals that AMR has been increasing steadily since the introduction of antimicrobial drugs (AMDs) (2). Meat production systems are thought to contribute to the problem by harboring a reservoir of AMR that interfaces with humans either through persistence in the food chain or dissemination of wastes into the environment (3–6). Antimicrobial use (AMU) in food producing animals is often cited as a driver of AMR in humans, but it is extremely challenging to design and execute studies that can be used to infer causality between the two. As a result, producers and policy makers alike have relatively little high-quality evidence on which to base informed and rational decisions with regard to AMU and other production management practices. The four studies presented in this doctoral thesis attempt to overcome some of the obstacles that currently impede inferential analysis regarding AMU practices and AMR. The first two studies stem from a project in which detailed AMU and AMR data were collected throughout the feeding period for over 5,000 individual cattle across 300 pens. The unprecedented collection of prospective data from such a large number of uniquely identified commercial cattle enabled us to achieve a much more robust level of causal inference compared to many previous studies. The last two studies employed shotgun metagenomics to interrogate the entire AMR potential (the “resistome”) of a given sample, enabling novel insight into the longitudinal, microbe-level genetic ecology of AMR within beef production systems. Because AMR develops and is maintained within the genetic context a microbial population, the resistome-microbiome approach contributes a critical and long-lacking piece to the overall puzzle of AMR within beef production. Thus, while each study in this dissertation approaches the research question of AMR from a slightly different angle, all of them provide crucial and novel information to our scientific understanding of AMU and AMR in beef production. The 4 studies also complement one another through investigation of different aspects of AMU and AMR across nearly the entire beef production system. The first study not only investigates AMU-AMR associations within Mannheimia haemolytica, but also examines how these associations affect respiratory-related morbidity and mortality outcomes in commercial cattle. As such, this study is focused on the animal health and economic dimensions of AMU and AMR in a critically important respiratory pathogen. The second study investigates within-feedlot AMU-AMR associations in non-type-specific Escherichia coli, a widely used “indicator” species for AMR, and compares different analytical methods for analyzing the types of data collected as part of ongoing surveillance of AMR in livestock production. Therefore, this study focuses on the public health and regulatory dimension of AMU-AMR in feedlot beef production. The third study… Advisors/Committee Members: Morley, Paul S. (advisor), Belk, Keith E. (committee member), Boucher, Christina (committee member), Gow, Sheryl P. (committee member), McAllister, Timothy A. (committee member).

Subjects/Keywords: antimicrobial use; feedlot; resistome; cattle; antimicrobial resistance; microbiome

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APA (6^th Edition):

Noyes, N. R. (2016). Epidemiology and ecology of antimicrobial use and resistance in North American beef production systems, The. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/173328

Chicago Manual of Style (16^th Edition):

Noyes, Noelle Robertson. “Epidemiology and ecology of antimicrobial use and resistance in North American beef production systems, The.” 2016. Doctoral Dissertation, Colorado State University. Accessed January 16, 2021. http://hdl.handle.net/10217/173328.

MLA Handbook (7^th Edition):

Noyes, Noelle Robertson. “Epidemiology and ecology of antimicrobial use and resistance in North American beef production systems, The.” 2016. Web. 16 Jan 2021.

Vancouver:

Noyes NR. Epidemiology and ecology of antimicrobial use and resistance in North American beef production systems, The. [Internet] [Doctoral dissertation]. Colorado State University; 2016. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/10217/173328.

Council of Science Editors:

Noyes NR. Epidemiology and ecology of antimicrobial use and resistance in North American beef production systems, The. [Doctoral Dissertation]. Colorado State University; 2016. Available from: http://hdl.handle.net/10217/173328

Queen Mary, University of London

28. Phee, Lynette. Unorthodox antimicrobial combination therapies for the treatment of multi-drug resistant Gram-negative infections.

Degree: PhD, 2018, Queen Mary, University of London

URL: http://qmro.qmul.ac.uk/xmlui/handle/123456789/44695 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.766221

► The rise of antimicrobial resistance (AMR) has culminated in the most pressing problem in modern medicine. The situation is most acute with regards to the… (more)

▼ The rise of antimicrobial resistance (AMR) has culminated in the most pressing problem in modern medicine. The situation is most acute with regards to the management of multi- drug resistant Gram-negative infections (MDRGNB) with common infections increasingly untreatable due to rapidly dwindling therapeutic options. A solution to the problem of AMR is unlikely to be easily found, but revisiting and re-purposing existing antimicrobials is a viable approach in the medium term. This study investigated the use of unorthodox antimicrobial combination therapies for the treatment of MDRGNB, with particular focus on agents of last resort. A systematic review of clinical studies highlighted the potential for polymyxin (colistin) combination therapies (e.g. colistin-rifampicin, colistin-carbapenems), although this could not be supported in a formal meta-analysis. A systematic approach for screening MDRAB for susceptibility to novel colistin combinations using multiple methods was employed and uncovered a number that were more potent than those previously identfied. The most potent combination that was consistently identified was colistin when combined with fusidic acid, despite this drug having no useful activity against MDRGNB on its own. The combination was further evaluated in static time-kill assays against a range of Gram-negative pathogens with defined resistance mechanisms, including to polymyxins and using invertebrate (Galleria mellonella) and murine models of MDRGNB infection. Colistin and fusidic acid combination therapy was subsequently used to successfully treat a case of ventilator-associated pneumonia due to MDR A. baumannii. This work highlights how older drugs can be re-purposed to tackle the problem of AMR using a precision medicine approach. Further studies to elucidate the mechanism of action of the colistin- fusidic acid combination and a formal clinical trial are warranted to investigate the potential utility of this combination in the treatment of MDRGNB with the expressed goal of bridging the current antimicrobial development gap.

Subjects/Keywords: Immunobiology; Antimicrobial Combination Therapies; antimicrobial resistance; gram-negative infections

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APA (6^th Edition):

Phee, L. (2018). Unorthodox antimicrobial combination therapies for the treatment of multi-drug resistant Gram-negative infections. (Doctoral Dissertation). Queen Mary, University of London. Retrieved from http://qmro.qmul.ac.uk/xmlui/handle/123456789/44695 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.766221

Chicago Manual of Style (16^th Edition):

Phee, Lynette. “Unorthodox antimicrobial combination therapies for the treatment of multi-drug resistant Gram-negative infections.” 2018. Doctoral Dissertation, Queen Mary, University of London. Accessed January 16, 2021. http://qmro.qmul.ac.uk/xmlui/handle/123456789/44695 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.766221.

MLA Handbook (7^th Edition):

Phee, Lynette. “Unorthodox antimicrobial combination therapies for the treatment of multi-drug resistant Gram-negative infections.” 2018. Web. 16 Jan 2021.

Vancouver:

Phee L. Unorthodox antimicrobial combination therapies for the treatment of multi-drug resistant Gram-negative infections. [Internet] [Doctoral dissertation]. Queen Mary, University of London; 2018. [cited 2021 Jan 16]. Available from: http://qmro.qmul.ac.uk/xmlui/handle/123456789/44695 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.766221.

Council of Science Editors:

Phee L. Unorthodox antimicrobial combination therapies for the treatment of multi-drug resistant Gram-negative infections. [Doctoral Dissertation]. Queen Mary, University of London; 2018. Available from: http://qmro.qmul.ac.uk/xmlui/handle/123456789/44695 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.766221

George Mason University

29. Haymond, Amanda Nicole. Novel Antimicrobial Development by Targeting the First Two Committed Enzymes in the Methyl Erythritol Phosphate Pathway, DXP Reductoisomerase and MEP Cytidylyltransferase .

Degree: 2017, George Mason University

URL: http://hdl.handle.net/1920/11249

► The threat of both natural and engineered acquisition of antibiotic resistance by microbes necessitates development of novel antimicrobial compounds. The methyl erythritol phosphate (MEP) pathway… (more)

Subjects/Keywords: Biochemistry; antibiotics; antimicrobial development; antimicrobial resistance; enzymology; MEP pathway

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APA (6^th Edition):

Haymond, A. N. (2017). Novel Antimicrobial Development by Targeting the First Two Committed Enzymes in the Methyl Erythritol Phosphate Pathway, DXP Reductoisomerase and MEP Cytidylyltransferase . (Thesis). George Mason University. Retrieved from http://hdl.handle.net/1920/11249

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Haymond, Amanda Nicole. “Novel Antimicrobial Development by Targeting the First Two Committed Enzymes in the Methyl Erythritol Phosphate Pathway, DXP Reductoisomerase and MEP Cytidylyltransferase .” 2017. Thesis, George Mason University. Accessed January 16, 2021. http://hdl.handle.net/1920/11249.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Haymond, Amanda Nicole. “Novel Antimicrobial Development by Targeting the First Two Committed Enzymes in the Methyl Erythritol Phosphate Pathway, DXP Reductoisomerase and MEP Cytidylyltransferase .” 2017. Web. 16 Jan 2021.

Vancouver:

Haymond AN. Novel Antimicrobial Development by Targeting the First Two Committed Enzymes in the Methyl Erythritol Phosphate Pathway, DXP Reductoisomerase and MEP Cytidylyltransferase . [Internet] [Thesis]. George Mason University; 2017. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/1920/11249.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Haymond AN. Novel Antimicrobial Development by Targeting the First Two Committed Enzymes in the Methyl Erythritol Phosphate Pathway, DXP Reductoisomerase and MEP Cytidylyltransferase . [Thesis]. George Mason University; 2017. Available from: http://hdl.handle.net/1920/11249

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Melbourne

30. Lam, Shu Jie. Structurally nanoengineered peptide polymers for combating multidrug-resistant bacteria.

Degree: 2016, University of Melbourne

URL: http://hdl.handle.net/11343/128246

► Antimicrobial resistance has been named as one of the clinical ‘super-challenges’ of the 21st century. With the rise and prevalence of multi-drug resistant (MDR) ‘superbugs’,… (more)

▼ Antimicrobial resistance has been named as one of the clinical ‘super-challenges’ of the 21st century. With the rise and prevalence of multi-drug resistant (MDR) ‘superbugs’, such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and more recently, the ‘ESKAPE’ pathogens, a return to the pre-antibiotic era is rapidly becoming a reality in many parts of the world. Infections caused by MDR pathogens are a major burden to modern healthcare, as the available treatment options are drastically reduced, leading to increased treatment costs, and high morbidity and mortality rates. However, this growing epidemic of infections caused by MDR pathogens has not been accompanied by an increase in the discovery of novel antimicrobials. In fact, it has been reported that aside from a few narrow spectrum drugs and teixobactin, no new chemical class of antibiotics has appeared in the last 40 years. The challenge remains to develop antimicrobial agents with new mechanisms of action that can overcome acquired resistance without contributing to resistance development. Over the past few years, our work in drug and gene delivery has demonstrated the potential of star peptide polymers as therapeutic agents, with significant advantages over linear peptides. Building on our prior knowledge, this thesis explores the possibility of using macromolecular engineering techniques to design and develop star peptide polymers that could function as novel antimicrobial agents capable of combating antibiotic-resistant bacteria. Inspired by antimicrobial peptides (AMPs) that form part of the innate immune response in multicellular organisms, 16-and 32-arm star peptide polymers were synthesized, with arms composed of cationic and hydrophobic amino acid moieties co-polymerized in a random fashion. The star polymers were found to demonstrate superior efficacy against clinically-relevant Gram-negative bacteria, including MDR species, compared to their linear ‘one arm’ equivalent and several well-known AMPs, while possessing high therapeutic indices. The lack of any observable bacterial resistance development against the star peptide polymers was attributed to their unique, multi-modal antimicrobial mechanism, which differs from that of antibiotics and AMPs. Based on these attributes, the star peptide polymers were classified as a new class of antimicrobial agents, referred to as ‘Structurally Nanoengineered Antimicrobial Peptide Polymers’ (SNAPPs). The subsequent part of this thesis focused on developing further understanding on the structural design and bio-nano interactions of SNAPPs. Through a structure-activity relationship study, the effects of the star arm (co)polymer structure and overall macromolecular architecture on antimicrobial activity and biocompatibility were investigated. Further, the behavior of SNAPPs in physiologically-relevant settings, such as in a bloodstream-mimicking environment, was probed in terms of their antimicrobial efficacy and mode of action. Lastly, this thesis also…

Subjects/Keywords: peptide; antimicrobial; star polymer; bacteria; antimicrobial resistance; polymerization

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Lam, S. J. (2016). Structurally nanoengineered peptide polymers for combating multidrug-resistant bacteria. (Doctoral Dissertation). University of Melbourne. Retrieved from http://hdl.handle.net/11343/128246

Chicago Manual of Style (16^th Edition):

Lam, Shu Jie. “Structurally nanoengineered peptide polymers for combating multidrug-resistant bacteria.” 2016. Doctoral Dissertation, University of Melbourne. Accessed January 16, 2021. http://hdl.handle.net/11343/128246.

MLA Handbook (7^th Edition):

Lam, Shu Jie. “Structurally nanoengineered peptide polymers for combating multidrug-resistant bacteria.” 2016. Web. 16 Jan 2021.

Vancouver:

Lam SJ. Structurally nanoengineered peptide polymers for combating multidrug-resistant bacteria. [Internet] [Doctoral dissertation]. University of Melbourne; 2016. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/11343/128246.

Council of Science Editors:

Lam SJ. Structurally nanoengineered peptide polymers for combating multidrug-resistant bacteria. [Doctoral Dissertation]. University of Melbourne; 2016. Available from: http://hdl.handle.net/11343/128246

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Open Access Theses and Dissertations