Abstract

This study investigated the levels and patterns of antibiotic resistance in resistance- indicator bacteria; Escherichia coli and Enterococci of food of animal origin. Isolates were obtained from fecal samples collected from food animals (chickens, pigs, cattle, goats and sheep) and tested against selected panels of antibiotics. High resistance was observed for both Enterococci species and E. coli. Enterococciisolates showed high resistance against erythromycin (60.5%), gentamycin (58.9%) and tetracycline (46.8%) and lowest resistance against penicillin. E. coli isolates showed highest resistance against erythromycin (96.0%), tetracycline (61%) and ampicillin (55.3%), and showed least resistance to gentamycin (6.9%), ciprofloxacin (6.5%) and aztreonam (8.8%), and no resistance to meropenem. Comparison of resistance between E. coli and Enterococci isolates from the same animal hosts for different antibiotics indicated that resistance was significantly higher in E. coli (p < 0.05) for erythromycin, cotrimoxazole, and ampicillin than it was in Enterococci but it was significantly lower than in Enterococci for gentamycin, chloramphenicol and ciprofloxacin. Overall 35 and 46 percent of Enterococci and E. coli were resistant to five or more antibiotics, respectively. The high level of multi-drug resistance to clinically important antibiotics in commensal indicator bacteria is reservoir of a resistant gene pool that may spread resistance to pathogens in animals and has public health implications.

Key words: Antimicrobial resistance, commensal bacteria, food animals.