Rapid detection of Escherichia coli gyrA and parC mutants in one-day-old broiler chicks in Iran

Abstract

Vertical and consequently horizontal transmission of quinolone and fluoroquinolone resistant Escherichia coli clones following hatch in chickens enables a massive amplification of these clones into a large population. The aim of this study was to determine the antibiotic resistance and susceptibility of Iranian E. coli isolates (n=105) from one-day-old chicks to fluoroquinolones and the relation of this resistance with mutations in gyrA and parC genes using PCR-RFLP. For the first time, EcoRV restriction enzyme was used for rapid mutation screening in parC (Ser80Ile). The results showed that the low level of Minimum Inhibitory Concentration (MIC) for ciprofloxacin (0.25-4μg ml-1) and enrofloxacin (0.25-4μg ml-1) corresponded to a single mutation in gyrA, while intermediary to high level of MIC for ciprofloxacin (8→64 μg ml-1) and enrofloxacin (16→64 μg ml-1) were related to 2 mutations in gyrA or 3 mutations, 2 in gyrA and 1 in parC. There was a strong positive correlation (R = 0.93, P < 0.001) between MIC levels of enrofloxacin and ciprofloxacin among these isolates. The article concludes by stressing that the rising incidence of enrofloxacin resistant E. coli isolates from chicken sources may increase the potential risk of ciprofloxacin resistant E. coli acquisition by humans

Keywords

• Escherichia coli
• Fluoroquinolone resistance
• gyrA
• parC
• Iran
• one-day-old broiler chicks
• PCR-RFLP
• sequencing