Comparative Studies of Antimicrobial Resistance in <i>Escherichia coli</i>, <i>Salmonella</i>, and <i>Campylobacter</i> Isolates from Broiler Chickens with and without Use of Enrofloxacin

Abstract

This study investigated the effect of enrofloxacin (ENR) administration on the prevalence and antimicrobial resistance of E. coli, Salmonella, and Campylobacter isolated from broiler chickens under field conditions. The isolation rate of Salmonella was significantly lower (p Campylobacter isolation rate was significantly higher (p p E. coli isolates from farms that used ENR (88.1%) than farms that did not (78.0%). The respective ratio of resistance to ampicillin (40.5% vs. 17.9%), chloramphenicol (38.0% vs. 12.5%), tetracycline (63.3% vs. 23.2%), and trimethoprim/sulfamethoxazole (48.1% vs. 28.6%) and the ratio of intermediate resistance to ENR (67.1% vs. 48.2%) were significantly higher (p Salmonella isolates from the farms that used ENR than farms that did not. In conclusion, the use of ENR at broiler farms was an important factor in decreasing the prevalence of Salmonella but not Campylobacter and caused ENR resistance among E. coli and Salmonella but not Campylobacter. Exposure to ENR could have a co-selective effect on antimicrobial resistance in enteric bacteria in the field.

Keywords

• <i>E. coli</i>
• <i>Salmonella</i>
• <i>Campylobacter</i>
• enrofloxacin
• antimicrobial resistance
• broiler chicken