Characterization of antibiotic resistance in ampicillin and tetracycline resistant escherichia coli from feedlot cattle fed subtherapeutic antimicrobials
Date
2008
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Abstract
The study investigated tetracycline- and ampicillin-resistant Escherichia coli selected from feces of calves that were or were not administered in-feed subtherapeutic antimicrobials. Antimicrobial resistance (AMR) persisted throughout the experiment even in the absence of in-feed antibiotics. Transmission of E. coli isolates among cattle was evident, particularly among animals within a single pen. In addition, shedding of E. coli biotypes was observed to occur transiently throughout the feeding period. Administration of subtherapeutic levels of antimicrobials did not have a major impact on AMR E. coli as compared to control steers, except for the observation that administration of chlortetracycline and sulfamethazine increased the number of ampicillin-resistant isolates that also exhibited resistance to sulfamethoxazole and chloramphenicol. Molecular characterization of isolates found tet(B) to be the most prevalent determinant among the tetracycline-resistant isolates and teml-like determinant to be most prevalent among the ampicillin-resistant isolates. Results suggest that AMR inĀ£. coli is complex and is likely affected not only by the administration of antibiotics but also by numerous other presently undefined environmental and management factors.
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Bibliography: p. 118-131
some pages are in colour
some pages are in colour
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Citation
Mirzaagha, P. (2008). Characterization of antibiotic resistance in ampicillin and tetracycline resistant escherichia coli from feedlot cattle fed subtherapeutic antimicrobials (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/2302