Antimicrobial Resistance in Enterobacteriaceae Isolated from Liver of Commercial Broilers and Backyard Chickens

Abstract

SUMMARY In commercial farming, frequent use of antimicrobial agents probably results in the occurrence of resistance in bacterial flora present in the gastrointestinal tract. Backyard/free range chicken farming is known as a typical example of backyard farming. This kind of poultry farming differs in many ways from commercial poultry farming, e.g., in feeding regimes, antibiotic use, and access to outdoor areas. This survey investigated if these differences affect the antimicrobial resistance patterns of enteric bacteria isolated from liver samples of commercial broilers and backyard chickens. For this purpose, enteric bacteria from the family Enterobacteriaceae were isolated from livers of commercial broiler and backyard chickens in Pakistan and were screened for their antimicrobial resistance. Antibiogram results revealed that the number of multidrug-resistant Escherichia coli, Salmonella, and Klebsiella were higher in commercial broilers as compared to backyard chickens. The isolates from commercial broilers showed a higher percentage resistance as compared to backyard chickens for nine antibiotics (viz., ampicillin, doxycycline, amoxicillin, enrofloxacin, gentamicin, norfloxacin, flumequine, ciprofloxacin, and augmentin). Whereas for 2 antibiotics, chloramphenicol and oxytetracycline, the extent of resistance in backyard chicken isolates was significantly higher than those from commercial broilers. The results indicate that in Pakistan backyard farming may contribute less to antimicrobial resistance.