自贡市2014年农贸市场食品中单增李斯特菌污染状况调查

Contamination of Listeria monocytogenes from food in farmers' markets in Zigong City,2014

目的探索自贡市农贸市场食品中单核细胞增生性李斯特菌(单增李斯特菌,Listeria monocytogenes,L. monocyto-genes)的污染状况。方法 2014年12月采集四川自贡市农贸市场的各类食品样品,分离单增李斯特菌,采用血清分型,多位点序列分型(multilocus sequence typing,MLST)对分离的单增李斯特菌进行分子分型,并用脉冲场凝胶电泳(pulsedfield gel electrophoresis,PFGE)研究菌株之间的同源性。结果从农贸市场626份各类食品中检出单增李斯特菌48株(阳性率7. 67%),牛羊肉样品的菌株分离率(37. 50%)最高。菌株分为3种血清型:1/2a(17株,占35. 41%)、1/2b(22株,占45. 83%)、1/2c(9株,占18. 75%)。9种ST型,以ST87型(13株,占27. 08%)、ST8型(12株,占25. 00%)、ST9型(9株,占18. 75%)为主;PFGE分为21种PT型,9个PFGE带型的菌株来自不同种类的食品。结论自贡市各类食品中单增李斯特菌污染情况广泛存在,不同食品存在交叉污染,食品监督部门应加强市场卫生情况的监管。

Objective To investigate the contamination status of Listeria monocytogenes(L.monocytogenes)from food in farmers’markets in Zigong City.Methods L.monocytogenes strains were isolated from various food samples collected from farmers’markets in Zigong City,Sichuan Province in December 2014.Serological classification and multilocus sequence typing(MLST)were undertaken on the isolated strains to determine the sequence type,and pulsed field gel electrophoresis(PFGE)was used to analyze the homology among the strains.Results Forty-eight strains of L.monocytogenes were isolated from 626 food samples,with the positive detection rate of 7.67%.The prevalence of L.monocytogenes in beef and mutton samples was the highest(37.50%).Three serotypes were isolated from the 48 strains of L.monocytogenes,including serovars 1/2 a(35.41%,17/48),1/2 b(45.83%,22/48)and 1/2 c(18.75%,9/48).The results of MLST showed 9 different sequence types(STs),and the predominant STs were ST87(27.08%,13/48),ST8(25.00%,12/48)and ST9(18.75%,9/48).The PFGE typing divided the 48 strains into 21 pulse types(PTs),9 of which were isolated from different kinds of food.Conclusions L.monocytogenes contamination is widespread in various food in Zigong City;moreover,there exists cross-contamination of L.monocytogenes among different food.Therefore,the related authorities should strengthen the supervision of food in the farmers’markets.