AUTHOR=Tang Biao , Wang Jingge , Zheng Xue , Chang Jiang , Ma Jiangang , Wang Juan , Ji Xiaofeng , Yang Hua , Ding Baoan 

TITLE=Antimicrobial resistance surveillance of Escherichia coli from chickens in the Qinghai Plateau of China

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.885132

DOI=10.3389/fmicb.2022.885132

ISSN=1664-302X

ABSTRACT=<p>Antimicrobial resistance (AMR) may lead to worldwide epidemics through human activities and natural transmission, posing a global public safety threat. Colistin resistance mediated by the <italic>mcr-</italic>1 gene is the most prevalent among animal-derived <italic>Escherichia coli</italic>, and <italic>mcr-</italic>1-carrying <italic>E. coli</italic> have been frequently detected in central-eastern China. However, animal-derived <italic>E. coli</italic> with AMR and the prevalence of <italic>mcr</italic>-1 in the Qinghai Plateau have been rarely investigated. Herein, 375 stool samples were collected from 13 poultry farms in Qinghai Province and 346 <italic>E. coli</italic> strains were isolated, of which eight carried <italic>mcr-</italic>1. The AMR rates of the <italic>E. coli</italic> strains to ampicillin, amoxicillin/clavulanic acid, and tetracycline were all above 90%, and the resistance rates to ciprofloxacin, cefotaxime, ceftiofur, and florfenicol were above 70%. Multidrug-resistant strains accounted for 95.66% of the total isolates. Twelve <italic>E. coli</italic> strains showed colistin resistance, from which a total of 46 AMR genes and 36 virulence factors were identified through whole-genome sequencing. The <italic>mcr</italic>-1 gene resided on the IncHI2, IncI2-type and IncY-type plasmids, and <italic>mcr</italic>-1 was located in the <italic>nikA-nikB-mcr-</italic>1-<italic>pap2</italic> gene cassette (three strains) or the <italic>pap2-mcr-</italic>1-IS<italic>Apl1</italic> structure (one strain). Completed IncI2-type plasmid pMCR4D31–3 sequence (62,259 bp) revealed that it may cause the horizontal transmission of <italic>mcr-</italic>1 and may increase the risk of its spread through the food chain. Taken together, the AMR of chicken-derived <italic>E. coli</italic> in the plateau is of concern, suggesting that it is very necessary for us to strengthen the surveillance in various regions under the background of one health.</p>