Prevalence and Characterization of Fluoroquinolone Resistant Isolated From an Integrated Broiler Chicken Supply Chain.

The objectives of this study were to investigate the prevalence and fluoroquinolone resistant isolated from an integrated broiler chicken supply chain and their molecular characterization. In total, 73 isolates were recovered from a broiler chicken supply chain in Shanghai. isolates were tested for susceptibility to 11 antimicrobial agents using the broth dilution method and were characterized using pulsed-field gel electrophoresis (PFGE). Then, the isolates were examined for mutations in quinolone resistance-determining region (QRDR) of , , , and , and were screened for plasmid-mediated quinolone resistance (PMQR) genes. Lastly, we sequenced the plasmids carrying in six isolates from three sources (two isolated per source). Among 73 isolates, 45 isolates were identified as . Indiana, 24 were . Schwarzengrund, 2 were . Enteritidis, and 2 were . Stanleyville. In addition, high rates of resistance were detected for nalidixic acid (41.1%) and ciprofloxacin (37.0%), while resistance to other test agents was diverse (2.0-100%). . Indiana and . Schwarzengrund isolates from different sources exhibited the same PFGE pattern, suggesting that the isolates possessed high potential to spread along the broiler chicken supply chain. and exhibited frequent missense mutations. Moreover, was the most prevalent PMQR gene in the 73 isolates, and it was found about a new hybrid plasmid. This study concludes a high prevalence of fluoroquinolone resistant in chicken supply chain, threatening the treatment of foodborne diseases. In particular, the emergence of a new hybrid plasmid carrying indicates that the recombination of plasmid carrying resistance gene might be a potential risk factor for the prevention and control strategies of drug resistance.