AUTHOR=Zhao Xiaonan , Liu Zhengjie , Zhang Yin , Yuan Xiaomeng , Hu Ming , Liu Yuqing 

TITLE=Prevalence and Molecular Characteristics of Avian-Origin mcr-1-Harboring Escherichia coli in Shandong Province, China

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00255

DOI=10.3389/fmicb.2020.00255

ISSN=1664-302X

ABSTRACT=<p>The objective of this study was to evaluate the prevalence and characteristics of avian-origin <italic>mcr</italic>-1-harbouring <italic>Escherichia coli</italic> in Shandong Province, China. During 2017—2018, a total of 668 non-duplicate <italic>E. coli</italic> isolates were separately collected from 8eight large intensive poultry farms in Shandong Province. Antimicrobial susceptibility testing for 10 antimicrobial agents commonly used in farms was performed on all <italic>E. coli</italic> isolates by the agar dilution method; the mobile colistin resistance gene (<italic>mcr</italic>-1) gene was screened by PCR, and <italic>mcr</italic>-1 positive isolates were PCR-screened for antimicrobial resistance genes and typed by multi-locus sequence typing (MLST). Among the 668 <italic>E. coli</italic>, 102 (15.3%) harbored the <italic>mcr</italic>-1 gene; high antimicrobial resistance rates were observed for ampicillin (100/102, 98.0%), followed by amoxicillin (99/102, 97.1%) and florfenicol (97/102, 95.1%), and a low level of resistance was found for amoxicillin/clavulanic acid (24/102, 23.5%). Five ESBL genes were detected, and all isolates carried <italic>bla</italic><sub><italic>TEM</italic></sub> (102/102, 100%), followed by <italic>bla</italic><sub>CTX–M</sub> (90/102, 88.2%). Four PMQR genes were detected; <italic>aac(6)-Ib-cr</italic> (40/102, 39.2%) was the most commonly isolated PMQR gene, followed by <italic>qnrA</italic> (10/102, 9.8%). Thirty-eight different kinds of STs were identified, and the dominant ST was ST93 (19/102, 18.6%), followed by ST48 (9/102, 8.8%). In summary, <italic>E. coli</italic> from poultry in Shandong could be a reservoir for the <italic>mcr</italic>-1 gene, which could pose serious risks to human public health.</p>