新疆不同地区蛋鸡场鸡粪源与环境源大肠杆菌耐药性比较分析OA

The study was to investigate the differences in antimicrobial resistance(AMR)and the distribution of resistance genes between Escherichia coli isolates from chicken fecal samples and the environment samples in large-scale layer farms in Xinjiang under China's antimicrobial reduction policy,and to elucidate the association with the implementation of this policy,and to guide rational clinical antimicrobial use based on resistance phenotypes.In this study,a total of 500 chicken fecal samples and 141 environmental samples were collected using sterile swabs from five large-scale layer farms in Wujiaqu,Manas,Tacheng,Yanqi,and Kashi.Escherichia coli was isolated and identified from these samples,and the minimum inhibitory concentrations(MICs)of 10 antibiotics were determined using the agar dilution method,and 7 antimicrobial resistance genes were detected by PCR.The results showed as follows:1)496 strains of Escherichia coli were isolated,with an isolation rate of 77.3％(496/641).The isolation rates in each region,from highest to lowest,were as follows:Tacheng(88.6％,117/132),Yanqi(79.8％,99/124),Kashi(79.2％,99/125),Manas(71.8％,102/142),and Wujiaqu(66.7％,79/118).2)Environmental-source Escherichia coli isolates exhibited significantly higher overall AMR than fecal-source isolates.Among the ten antibiotics tested,high resistance rates(≥60.0％)were observed for seven antibiotics(70.0％)in environmental isolates,which was significantly higher than that for four antibiotics(40.0％)in fecal isolates.Specifically,environmental isolates exhibited significantly higher resistance rates to ampicillin,florfenicol,tetracycline,and enrofloxacin compared to fecal-source isolates.3)The detection rates of the tet(A)gene exceeded 70.0％in both fecal-source and environmental-source isolates.The detection rates of the blaTEM and floR genes were significantly higher in environmental-source isolates.In contrast,the blaNDM and mcr-1 genes were detected only in the fecal-source strains.In conclusion,under the antimicrobial reduction policy framework,variations in the prevalence of Escherichia coli among isolates from chicken fecal sources and environmental sources were observed across layer farms in 5 regions of Xinjiang,China.Environmental-source Escherichia coli isolates exhibited significantly higher antimicrobial resistance than fecal isolates,indicating that residual antibiotics in farm environments may drive the enrichment and dissemination of resistance genes.It is recommended to optimize antimicrobial usage based on regional resistance profiles,strengthening manure management and environmental disinfection and disrupting the"feces-water-soil"transmission chain to curb the spread of antimicrobial resistance.