四川省自贡市食品和环境携带屎肠球菌的耐药性和多位点序列分型研究

Antibiotic susceptibility and multilocus sequence typing of Enterococcus faecium strains isolated from foods and environment in Zigong,Sichuan

目的研究四川省自贡市食品和环境样本中屎肠球菌耐药性及携带毒力基因情况,并对分离菌株进行序列分型(ST)。方法对2013年采集的157份食品和环境样本进行屎肠球菌分离鉴定,全自动微生物鉴定仪检测屎肠球菌对14种常见抗生素的敏感性;使用聚合酶链式反应方法检测屎肠球菌携带毒力基因(hyl,esp)的情况,并应用多位点序列分型(MLST)方法对分离菌株进行序列分型。结果自贡地区肉制品和冰箱拭子样本屎肠球菌分离率为28.03%(44/157),其中耐药菌株的比例为86.36%(38/44)。分离菌株对红霉素、四环素和利福平的耐药率分别为65.91%(29/44)、31.82%(14/44)和27.27%(12/44),对环丙沙星,高浓度链霉素和高浓度庆大霉素以及氯霉素也有一定的耐药率。分离到1株喹奴普丁-达福普丁耐药的菌株。未检测到对青霉素类、糖肽类、脂肽类、喹诺酮类和恶唑烷酮类抗生素耐药的菌株。44株屎肠球菌分为38个ST型别,ST94克隆群为优势克隆群,包括13株菌。分离到1株CC17克隆群的屎肠球菌多重耐药菌株和1株ST957的八重耐药菌株。检测到2株携带esp基因的屎肠球菌。结论自贡市食品和环境中存在多种ST型别的屎肠球菌,且对多种抗生素耐药。应重视肉制品中耐药屎肠球菌对公众健康的潜在威胁。

Objective To investigate the antibiotic resistance and virulence gene carriage of Enterococcus faecium isolates from food and environmental samples collected from food markets in Zigong,Sichuan province,and to observe sequence typing（ ST） identified by multilocus sequence typing（ MLST）. Methods A total of 157 food and environmental samples,which included raw meat,cooked meat and refrigerator swabs,were collected in 2013 for E. faecium isolation and the drug susceptibility tests of the isolates were performed by automatic bacteriology identification instrument. The presence of two virulence genes（ hyl and esp） were detected with polymerase chain reaction（ PCR）,and ST types were detected by MLST analysis. Results Of 157 food samples and refrigerator swabs,44 E. faecium strains were isolated（ 28. 03%）,in which 38 were resistant to at least one antibiotic（ 86. 36%）. The resistant rate was 65. 91% for erythromycin（ 29/44）,31. 82% for tetracycline（ 14/44） and 27. 27% for rifampicin（ 12/44） respectively, while several strains showed resistance to ciprofloxacin（ 9. 09%,4/44）,high concentration streptomycin and gentamicin（ 11. 36%,5/44; 9. 09%,4/44） and chloramphenicol（ 6. 82%,3/44）. One quinupristin-dalfopristin-resistant E. faecium strain was isolated from a meat sample.Strains resistant to penicillin,glycopeptides,lipopeptides,quinolones and oxazolidinone were failed to detect in this study.Two virulence genes（ esp and hyl） were negatively distributed in 44 isolates,except two isolates carrying esp gene. The MLST analysis of 44 E. faecium isolates revealed 38 different ST types,10 strains belonged to known STs（ ST94,ST301,ST69,ST361 and ST957）. ST94 clonal complex was predominant,including 13 isolates. One multi-drug resistant strainE. faecium belonging to clonal complex 17（ CC17） and one ST957 isolate was also detected respectively in this study.Conclusion Multi-drug resistant E. faecium isolates with different STs contaminates food and environment in Zigong,suggesting that close attention should be paid to its potential threat to human health.