Distribution and genetic characterization of fluoroquinolone resistance gene among strains from chicken in China.

The prevalence and dissemination of the plasmid-mediated fluoroquinolone (FQ) resistance gene in are considered serious public health concerns worldwide. So far, no comprehensive large-scale studies have focused on the prevalence and genetic characteristics of the gene in isolated from chickens. Herein, this study aimed to investigate the prevalence, antimicrobial resistance (AMR) patterns, and molecular characteristics of chicken-originated -positive strains from chicken farms, slaughterhouses, and markets in 12 provinces of China in 2020-2021. The overall prevalence of the gene was 21.13% (56/265), with the highest prevalence in markets (36.11%, 26/72), followed in farms (17.95%, 21/117), and slaughterhouses (10.53%, 9/76). Only the and genes were detected, and the prevalence rate of the gene (19.25%, 51/265) was higher than that of the gene (1.89%, 5/265). Whole genome sequencing identified 37 distinct AMR genes and 15 plasmid replicons, and the most frequent mutation in quinolone resistance determining regions was (T57S; 91.49%, 43/47). Meanwhile, four different and two genetic environments were discovered among 47 -positive strains. In total, 21.28% (10/47) of the strains were capable of conjugative transfer, and all were -positive strains, with the majority of transferable plasmids being IncHI2 types ( = 4). Overall, the prevalence of -positive strains from chickens in China and their carriage of multiple resistance and virulence genes and transferable plasmids is a major concern, which calls for continuous surveillance of -positive and the development of measures to control its prevalence and transmission.IMPORTANCE is a common foodborne pathogen responsible for 155,000 deaths annually worldwide. Fluoroquinolones (FQs) are used as first-line drugs for the treatment of infections in several countries and regions. However, the emergence and increasing prevalence of the FQ-resistant gene in isolated from chickens have been widely reported. Gaining insight into the genetic mechanisms of AMR genes in chicken could lead to the development of preventive measures to control and reduce the risk of drug resistance. In this study, we identified -positive isolated from chickens in different regions of China and their AMR patterns and genome-wide characteristics, providing a theoretical basis for further control of their prevalence and transmission.