Fluoroquinolone-resistant Escherichia coli isolated from healthy broilers with previous exposure to fluoroquinolones: Is there a link?

Abstract

The occurrence of resistance to quinolones and fluoroquinolones in Escherichia coli isolated from healthy chickens and its relation to previous use of fluoroquinolones in Kashan, Iran, was evaluated. A total of 181 E. coli isolates was collected. Ninety-five (52.5%) of the chickens had a history of previous use of both flumequine and enrofloxacin; 86 (47,5%) chickens had not been exposed to antimicrobial agents previously. The proportion of strains resistant to nalidixic acid and ciprofloxacin was 100% and 41.9%, respectively. The differences between ciprofloxacin resistance rates in strains from chickens with previous expose to fluoroquinolones compared with isolates from chickens without a history of drug use was significant (49.5% vs 33.7%, p = 0.0461). It seems that use of fluoroquinolones constitutes a major selective pressure for resistance. The results of this survey indicate very high levels of resistance to fluoroquinolones in E. coli from poultry production in Iran, and suggest that this reservoir of resistance may affect the therapeutic potential of fluoroquinolones in human and veterinary medicine.