Antimicrobial resistance surveillance of from chickens in the Qinghai Plateau of China.

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 1 gene is the most prevalent among animal-derived , and 1-carrying have been frequently detected in central-eastern China. However, animal-derived with AMR and the prevalence of -1 in the Qinghai Plateau have been rarely investigated. Herein, 375 stool samples were collected from 13 poultry farms in Qinghai Province and 346 strains were isolated, of which eight carried 1. The AMR rates of the 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 strains showed colistin resistance, from which a total of 46 AMR genes and 36 virulence factors were identified through whole-genome sequencing. The -1 gene resided on the IncHI2, IncI2-type and IncY-type plasmids, and -1 was located in the 1- gene cassette (three strains) or the 1-IS structure (one strain). Completed IncI2-type plasmid pMCR4D31-3 sequence (62,259 bp) revealed that it may cause the horizontal transmission of 1 and may increase the risk of its spread through the food chain. Taken together, the AMR of chicken-derived 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.