2019—2020年汉中市食源性食品中ST198型肯塔基沙门菌的耐药性研究

Study on the antimicrobial resistance of Salmonella Kentucky ST198 from foodborne foods in Hanzhong from 2019 to 2020

中文关键词:  ST198型肯塔基沙门菌  食源性食品  全基因组测序  耐药性  耐药基因

英文关键词:Salmonella Kentucky ST198  foodborne foods  whole genome sequencing  antimicrobial resistance  resistance gene

中文摘要:

      目的 研究食源性食品中ST198型肯塔基沙门菌的分子流行病学及耐药特性。方法 对2019年7月至2020年5月从陕西省汉中市7家不同超市采集的冷冻整鸡和猪肉馅进行肯塔基沙门菌分离鉴定、血清型分型、药物敏感试验及全基因组测序。结果 158份冷冻整鸡和163份猪肉馅中共分离鉴定出129株沙门菌, 其中从6家超市共分离到14株ST198型肯塔基沙门菌。药物敏感试验显示, 14株ST198型肯塔基沙门菌均为多重耐药菌, 所有菌株同时对5类及以上抗菌药物耐药; 对左氧氟沙星、多西环素、卡那霉素、链霉素、四环素、环丙沙星耐药率均达到100%; 对头孢唑啉、氨苄西林、头孢噻肟、庆大霉素、氨曲南、头孢吡肟耐药率也达到92.86%; 这些菌株仅仅对头孢西丁、亚胺培南、美罗培南、多粘菌素完全敏感。其中产超广谱β-内酰胺酶(extended spectrum β-lactamases, ESBLs)阳性菌株检出率为92.86%。耐药基因检测显示, 14株ST198型肯塔基沙门菌同时发生染色体上喹诺酮耐药决定区(quinolone resistance determining region, QRDR) gyrA和parC双突变, 突变类型有Asp87Asn (85.71%)、Asp87Gly (14.29%)、Ser83Phe (100%)、Thr57Ser (100%)、Ser80Ile (100%)。ESBLs基因以blaCTX-M-55和blaTEM-141为主, 78.57%的菌株同时携带这2种基因, 14.29%的菌株携带blaCTX-M-14b。此外78.57%的菌株携带大环内酯类耐药基因mph(A)。系统发育树结果显示, ST198型肯塔基沙门菌在汉中市6家不同的超市间存在相同克隆分子菌株。结论 陕西省汉中市ST198型肯塔基沙门菌主要从冷冻整鸡中分离, 对喹诺酮类和三代头孢菌素及替代药物阿奇霉素耐药严重, ESBLs阳性率和喹诺酮耐药决定区发生突变率高。此菌在汉中市不同超市间有一定传播关系, 可能存在交叉污染和上一级污染来源的传播。

英文摘要:

      Objective To study the molecular epidemiology and antimicrobial resistance characteristics of Salmonella Kentucky (S. Kentucky) ST198 in foodborne foods. Methods Frozen whole chickens and pork fillings were collected from 7 different supermarkets in Hanzhong from July 2019 to May 2020, S. Kentucky isolation and identification, serotype identification, drug susceptibility testing and whole genome sequencing were performed on the samples. Results A total of 129 Salmonella strains were isolated and identified from 158 frozen whole chickens and 163 pork fillings, including 14 S. Kentucky ST198 strains isolated from 6 supermarkets. Drug sensitivity testing showed that 14 S. Kentucky ST198 were multi-drug resistant bacteria, and all strains were resistant to 5 or more antibacterial drugs; the resistance rate to levofloxacin, penicillin, kanamycin, streptomycin, tetracycline, and ciprofloxacin reached 100%; the resistance rate to cefazolin, ampicillin, cefotaxime, gentamicin, ampicillin, and cefepime also reached 92.86%; these strains were only completely sensitive to cefoxitin, imipenem, meropenem and colistin. The detection rate of extended spectrum β-lactamases (ESBLs) positive strains was 92.86%. Detection of resistance genes showed that all 14 S. Kentucky ST198 had both quinolone resistance determining region (QRDR) gyrA and parC mutations on the chromosome, and the mutation types were Asp87Asn (85.71%), Asp87Gly (14.29%), Ser83Phe (100%), Thr57Ser (100%), and Ser80Ile (100%). The blaCTX-M-55 and blaTEM-141 were the main genes encoding ESBLs, 78.57% of the strains carried both genes, and 14.29% of the strains carried blaCTX-M-14b. 78.57% of strains carried the macrolide resistance gene mph(A). The phylogenetic tree results showed that 14 S. Kentucky ST198 had same clone molecular strain among 6 different supermarkets in Hanzhong city. Conclusion S. Kentucky ST198 is mainly isolated from frozen whole chicken in Hanzhong, Shaanxi province. The resistance to quinolones, third-generation cephalosporins and alternative drugs is serious, the positive rate of ESBLs production and the mutation rate in the QRDR are high, there is a certain transmission relationship between different supermarkets in Hanzhong, and there may be co-transmission of cross-contamination and upper pollution sources.