自贡市肉及其制品中粪肠球菌耐药性毒力基因和多位点序列分析

目的了解四川省自贡市肉及其制品分离粪肠球菌的抗生素耐药性和携带毒力基因情况,以及多重耐药菌株的序列分型(ST)。方法 2013年4月17~21日对147份肉及其制品样品污染的粪肠球菌进行分离鉴定,使用全自动微生物鉴定仪对分离菌株的耐药性进行检验,应用聚合酶链式反应(PCR)方法检测分离到的粪肠球菌携带4种常见毒力基因的情况,并对多重耐药菌株进行多位点序列分型(MLST)研究。结果从147份肉及其制品样品中共分离到65株粪肠球菌,其中耐药菌株比例为58.5%(38/65);分离菌株对四环素的耐药率最高,为41.5%(27/65),对利福平、氯霉素和红霉素也均有较高的耐药率;分离菌株对高浓度链霉素和高浓度庆大霉素的耐药率分别达到了15.4%(10/65)和12.3%(8/65);未分离到对青霉素类(青霉素和氨苄西林)、糖肽类(万古霉素)和脂肽类(达托霉素)抗生素耐药的菌株。4种常见毒力基因(gel E、asa1、esp、cyl A)在65株分离株中均有携带,阳性率分别为56.9%(37/65)、21.5%(14/65)、9.2%(6/65)和7.7%(5/65)。14株多重耐药菌株共有9个MLST型别,包括4株ST16、2株ST81和2株ST480菌株,且相同ST型别的粪肠球菌有相似的耐药谱和毒力基因携带情况。结论四川省自贡市肉及其制品中相同ST型别的粪肠球菌有相似的耐药谱和毒力基因携带情况,应重视肉及其制品中耐药粪肠球菌对公众健康的潜在威胁。

Antimicrobial susceptibility, virulence genes and multilocus sequence typing of Enterococcus faecalis strains isolated from meat and meat products in Zigong City

To investigate the antibiotic resistance and the distribution of virulence genes in Enterococcus faecalis isolated from meat and meat products collected from food market in Zigong City, Sichuan Province, and to observe sequence typing(ST)identified by multilocus sequence typing (MLST) among multi-drug resistant Enterococcus faecalis. Methods Enterococcus faecalis strains were isolated from 147 meat samples including raw meats and cooked meats from 17 to 21 April,2013. The antimicrobial susceptibilities of Enterococcus faecalis isolates were determined by automatic bacteriology identification. The presence of four virulence genes (cylA, asa1, gelE and esp) were investigated by polymerase chain reaction(PCR), and ST types were detected in multi-drug resistant isolates. Results A total of 65 isolates were obtained from 147 samples, 58.5%(38/65)of the isolates were resistant to at least one drug. Of all isolates, resistance to tetracycline was the highest (41.5%,27/65), and resistance to rifampicin, chloramphenicol and erythromycin was also fairly high. Moreover, resistance to high concentrations of streptomycin and gentamicin in Enterococcus faecalis isolates were 15.4%(10/65) and 12.3%(8/65), respectively. Strains resistant to penicillin, glycopeptides and lipopeptides were failed to acquire in this study. Four virulence genes which were common in Enterococcus faecalis were distributed in all 65 isolates, and the positive rates of gelE , asa1, esp and cylA were 56.9%(37/65),21.5%(14/65),9.2%(6/65) and 7.7%(5/65), respectively. There were 14 isolates, which showed resistance to three or more antibiotics, belonged to 9 STs mainly comprised of ST16 (n=4), ST81 (n=2) and ST480 (n=2). The profile of resistance and virulence genes were similar in the Enterococcus faecalis isolates with same STs. Conclusion The same ST type of Enterococcus faecalis strains from meat and meat products in Zigong City harbored similar virulence genes and multi-drug resistant pattern, which should be paid attention to the potential threat to human health.