石河子市鸡生产供应链中粪肠球菌和屎肠球菌的耐药性分析及耐药基因检测OA

To investigate the antimicrobial resistance profiles and prevalence of resistance genes among enterococci along the chicken production supply chain(including hatcheries,farms,slaughterhouses,and supermarkets)in Shihezi City,Xinjiang,a total of 316 samples were collected to isolate and identify Enterococcus faecalis and Enterococcus faecium.The minimum inhibitory concentrations(MICs)of 9 antimicrobial agents were determined by agar dilution method,and 11 antimicrobial resistance genes were detected by PCR.The results were as follows:1)A total of 258 enterococcal strains were isolated,with isolation rates of 66.8％(211/316)for E.faecalis and 14.9％(47/316)for E.faecium.Among them,the isolation rate of E.faecalis exceeded 80.0％in both hatcheries(91.8％)and supermarkets(80.7％),while E.faecium showed the highest isolation rate(20.9％)in slaughterhouses.2)The severity of antimicrobial resistance in Enterococcus isolates from different production stages was in the order of hatchery＞farm＞slaughterhouse＞supermarket.Enterococcus isolates from the hatchery exhibited 100.0％resistance to florfenicol,erythromycin,tetracycline,and linezolid.In addition,both E.faecalis and E.faecium showed high resistance rates to tetracycline,florfenicol,and erythromycin,with resistance rates of 99.1％,95.3％,and 93.4％for E.faecalis,and 95.7％,100.0％,and 76.6％for E.faecium,respectively.All isolates were fully susceptible to tigecycline and vancomycin.3)Multidrug resistance(MDR)analysis showed that E.faecalis isolates along the chicken supply chain were predominantly resistant to 4-6 antimicrobials(91.0％),with more than 60.0％of strains resistant to 6 agents in hatcheries and slaughterhouses.For E.faecium,resistance to 5 antimicrobials(62.5％)was dominant in farm isolates,whereas resistance to 3 antimicrobials(57.1％)was most common in isolates from supermarkets.4)Detection of resistance genes revealed that the tetracycline resistance gene tetM was detected in more than 85.0％of both E.faecalis(94.8％)and E.faecium(85.1％),and a positive correlation was observed between phenotypic resistance to tetracycline and the presence of tetM.The detection rate of the oxazolidinone resistance gene optrA in E.faecalis(56.0％)was slightly lower than that in E.faecium(62.0％),while the poxtA gene was more prevalent in E.faecium(19.2％).The cfr and vanA genes were not detected in any isolate.In conclusion,E.faecalis and E.faecium isolated from the chicken production supply chain in Shihezi City display severe antimicrobial resistance and carry multiple resistance genes.Standardized antimicrobial usage at the farm level and enhanced biosecurity control during slaughter and processing are recommended to reduce the risk of transmission of drug-resistant bacteria and resistance genes along the food chain.