AUTHOR=Cui Mingquan , Zhang Peng , Li Jiyun , Sun Chengtao , Song Li , Zhang Chunping , Zhao Qi , Wu Congming 

TITLE=Prevalence and Characterization of Fluoroquinolone Resistant Salmonella Isolated From an Integrated Broiler Chicken Supply Chain

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.01865

DOI=10.3389/fmicb.2019.01865

ISSN=1664-302X

ABSTRACT=<p>The objectives of this study were to investigate the prevalence and fluoroquinolone resistant <italic>Salmonella</italic> isolated from an integrated broiler chicken supply chain and their molecular characterization. In total, 73 <italic>Salmonella</italic> isolates were recovered from a broiler chicken supply chain in Shanghai. <italic>Salmonella</italic> 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 <italic>Salmonella</italic> isolates were examined for mutations in quinolone resistance-determining region (QRDR) of <italic>gyrA</italic>, <italic>gyrB</italic>, <italic>parC</italic>, and <italic>parE</italic>, and were screened for plasmid-mediated quinolone resistance (PMQR) genes. Lastly, we sequenced the plasmids carrying <italic>qnrS1</italic> in six <italic>Salmonella</italic> isolates from three sources (two isolated per source). Among 73 <italic>Salmonella</italic> isolates, 45 isolates were identified as <italic>S</italic>. Indiana, 24 were <italic>S</italic>. Schwarzengrund, 2 were <italic>S</italic>. Enteritidis, and 2 were <italic>S</italic>. 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%). <italic>S</italic>. Indiana and <italic>S</italic>. Schwarzengrund isolates from different sources exhibited the same PFGE pattern, suggesting that the <italic>Salmonella</italic> isolates possessed high potential to spread along the broiler chicken supply chain. <italic>gyrA</italic> and <italic>parC</italic> exhibited frequent missense mutations. Moreover, <italic>qnrS1</italic> was the most prevalent PMQR gene in the 73 <italic>Salmonella</italic> isolates, and it was found about a new hybrid plasmid. This study concludes a high prevalence of fluoroquinolone resistant <italic>Salmonella</italic> in chicken supply chain, threatening the treatment of <italic>Salmonella</italic> foodborne diseases. In particular, the emergence of a new hybrid plasmid carrying <italic>qnrS1</italic> indicates that the recombination of plasmid carrying resistance gene might be a potential risk factor for the prevention and control strategies of drug resistance.</p>