Authors: Amosun, E. A. , Ojo, O. E. *, Alao, I. K. and Ajuwape, A. T. P.
African Journal of Biotechnology Vol. 11(58), pp. 12240-12245,2012
Abstract
Commensal bacteria contribute to the distribution and persistence of antimicrobial resistance in the environment. This study monitored antimicrobial resistance in commensal Escherichia coli from the faeces of on-farm and slaughter cattle and beef. A total of 342 (89.5%) E. coli isolates were obtained from 382 samples. Isolation rate of E. coli was 90.0% in on-farm cattle, 87.1% in slaughter cattle and 92.2% in beef. Overall, the isolates showed resistance to amoxicillin (97.9%), ampicillin (97.9%), cefuroxime (25.1%), chloramphenicol (69.3%), ciprofloxacin (11.7%), cotrimazole (45.9%), erythromycin (59.4%), gentamycin (36.5%),nalidixic acid (27.2%), nitrofuratoin (54.9%),norfloxacin (21.1%), ofloxacin(14.0%), streptomycin (78.9%) and tetracycline (33.9%). There were no significant differences in antimicrobial resistance of E. coli from the different sample types. Only four (1.2%) of the 342 isolates were susceptible to all antimicrobial agents, while 338 (98.8%) were resistant to at least one of the tested antimicrobial agents. Multi-drug resistance to three or more antimicrobials was observed in 321 (93.9%) of all the isolates. Forty-one resistance groups were observed in on-farm cattle, 30 in slaughter cattle and 34 in beef. All the 30 resistance groups found in slaughter cattle were also present in on-farm cattle and beef. ‘AmoAmpChlEryNitStr’ and ‘AmoAmpChlStr’ were the predominant resistant patterns. This study confirmed on-farm and slaughter cattle as important sources of antimicrobial resistant E. coli transmissible to humans through beef
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