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

dc.contributor.authorLussier, Pamela
dc.contributor.authorUniversity of Lethbridge. Faculty of Arts and Science
dc.contributor.supervisorSelinger, L. Brent
dc.date.accessioned2011-11-17T23:03:38Z
dc.date.available2011-11-17T23:03:38Z
dc.date.issued2010
dc.degree.levelMasters
dc.descriptionxii, 104 leaves : ill. ; 28 cmen_US
dc.description.abstractThis 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.identifier.urihttps://hdl.handle.net/10133/2563
dc.language.isoen_USen_US
dc.publisherLethbridge, Alta. : University of Lethbridge, Dept. of Biological Science, 2010en_US
dc.publisher.departmentDepartment of Biological Scienceen_US
dc.publisher.facultyArts and Scienceen_US
dc.relation.ispartofseriesThesis (University of Lethbridge. Faculty of Arts and Science)en_US
dc.subjectBeta lactamases -- Researchen_US
dc.subjectEscherichea coli -- Researchen_US
dc.subjectAnti-infective agentsen_US
dc.subjectFeedlots -- Alberta, Southernen_US
dc.subjectCattle -- Alberta, Southernen_US
dc.subjectDissertations, Academicen_US
dc.titleCharacterization of putative extended-spectrum β-lactamases (ESBL) producing Escherichia coli isolated from feedlot cattle in Southern Albertaen_US
dc.typeThesisen_US
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