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Characterization of putative extended-spectrum β-lactamases (ESBL) producing Escherichia coli isolated from feedlot cattle in Southern Alberta

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dc.contributor.advisor Selinger, Brent
dc.contributor.author Lussier, Pamela
dc.contributor.author University of Lethbridge. Faculty of Arts and Science
dc.date.accessioned 2011-11-17T23:03:38Z
dc.date.available 2011-11-17T23:03:38Z
dc.date.issued 2010
dc.identifier.uri http://hdl.handle.net/10133/2563
dc.description xii, 104 leaves : ill. ; 28 cm en_US
dc.description.abstract This thesis describes the detection, and characterization of putative extended-spectrum β-lactamases (ESBLs) producing Escherichia coli isolated from feedlot cattle in southern Alberta. Cattle either received no antimicrobials or were administered subtherapeutic antimicrobials in feed. In total, 7,184 E. coli isolates were collected, and screened for resistance to either ceftazidime (2μg mL-1 ) or cefpodoxime (2μg mL-1), and from these results 237 E. coli isolates were considered presumptive ESBL producers. Antimicrobial resistant bacteria were isolated throughout the experiment; however, ESBL-producing E. coli were not prevalent throughout the study. In total, only three isolates (B221B1, C152C1, C98A1) exhibited the ESBL phenotype. Molecular subtyping of these isolates revealed no clonality between these strains. Molecular characterization of the 237 isolates investigated in this study revealed blaTEM to be the most prevalent AMR determinant among the ampicillin-resistant isolates with resistance to ceftazidime (2μg mL-1 ) or cefpodoxime (2μg mL-1). These data suggest that ESBLs are not frequent among Canadian feedlot cattle and MDR resistance (55 of 237) was observed but is not prominent among both the subgroup and total isolates collected. It was determined that isolate B221B1 was ESBL-producing, and harboured the blaTEM-1 gene. The genes responsible for ESBL production in isolates C98A1 and C152C1 were not characterized. In order to characterize the antimicrobial resistance (AMR) genes coding for ESBL-production in these 2 isolates, cloning and conjugation experiments were attempted. However, I was unable to resolve the mechanism responsible for ESBL phenotype in these two isolates. The results of this study imply that the development of ESBL-producing E. coli is complex, and is probably affected by both the administration of antimicrobials and numerous other presently undefined environmental factors. en_US
dc.language.iso en_US en_US
dc.publisher Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Science, 2010 en_US
dc.relation.ispartofseries Thesis (University of Lethbridge. Faculty of Arts and Science) en_US
dc.subject Beta lactamases -- Research en_US
dc.subject Escherichea coli -- Research en_US
dc.subject Anti-infective agents en_US
dc.subject Feedlots -- Alberta, Southern en_US
dc.subject Cattle -- Alberta, Southern en_US
dc.subject Dissertations, Academic en_US
dc.title Characterization of putative extended-spectrum β-lactamases (ESBL) producing Escherichia coli isolated from feedlot cattle in Southern Alberta en_US
dc.type Thesis en_US
dc.publisher.faculty Arts and Science en_US
dc.publisher.department Department of Biological Science en_US

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