| Yersinia enterocolitica is a widely spread foodborne pathogen. It is often transmitted tohumans via food chains. Many studies on prevalence of contamination by Y.enterocoliticafocused on raw meat, frozen food. But Y.enterocolitica contaminations in aquatic food,vegetables, edible fungi, dairy have little been reported. In this study, we evaluated thecontamination of Y.enterocolitica in major foods in China. The food including raw meat,frozen food, aquatic food, ready-to-eat foods, vegetables, edible fungi and dairy werecollected in Shanghai, Hefei, Nanchang, Wuhan, Chengdu, Kunming, Lanzhou, Harbin, Xi’an,Taiyuan, Beijing, Jinana, Guangzhou(fiveareas), Shenzhen, Shantou, Zhanjiang, Shaoguan,Heyuan, Fuzhou, Xiamen, Nanning,Beihai, Haikou and Sanya. Additionally, research onmajor virulence genes, serotype and antibiotic resistances of Y.enterocolitica strains isolatedfrom some cities. Finally, The isolates were genotyped by enterobacterial repetitive intergenicconsensus sequence polymerase chain reaction (ERIC-PCR), and then the distribution andgenetic diversity were studied through cluster analysis. It can provide the basic for theprevention and control of Y.enterocolitica pollution in foods.1.70samples were positive for Y.enterocolitica among1531samples collected frommarkets. The average positive rate was4.6%. Y.enterocolitica contaminations only were foundin three kinds of foods. The contamination rates in raw meat, frozen food and edible fungiwere9.8%,15.4%and1.8%respectitively. The highest positive rate of Y.enterocolitica amongthese cities was18.2%in Jinan, and the lowest was0.0%at Shenzhen andZhanjiang. ComparingY.enterocolitica pollution situation with the samples from different markets, the positive ratefrom supermarkets (5.2%) was slightly higher than from freemarkets (4.3%).2. According to the virulence gene tests on72Y.enterocolitica isolates from some cities,ail, ystB, ystA, virF and yadA were detected with the percentage of1.4%(1/72),70.8%(51/72),1.4%(1/72),1.4%(1/72) and1.4%(1/72) respectively. Isolates virulence genes weren’t widelyspread. Serological tests carried out on72Y.enterocolitica isolates for mainly five kinds ofserum including O:1,2, O:3, O:5, O:8, O:9, the detection rates were19.4%(14/72) O:9,8.3%(6/72) O:3,5.6%(4/72) O:8,4.2%(3/72) O:1,2and O:3, other strains have not identified and serotype. O:9was main serotype. What’s more, results of antibiotic resistancetests suggest spread existence of drug-resistant strains, many strains resistant to three or moreantibiotics, which indicate that the strains isolated from foods have strong drug-resistant.3. To further study the genetic diversity of the Y.enterocolitica,72Y.enterocolitica strainsisolated from foods were genotyped by ERIC-PCR with the optimized reaction conditions.Through cluster analysis, we found that72isolates have been divided into four large clustersof56types, similarity coefficient was between0.42-1.00. It showed a high genetic diversityand with third group taking the majority. ERIC-PCR fingerprints database of Y.enterocoliticahave been preliminarily established, which will be useful for establishing effectively tracingsource system of Y.enterocolitica and controlling the food contamination in future.We can adjust the scope of future research, more comprehensive and more targeted tograsp the importance of food-related pollution, specifically for the following three areas: rapiddetection technology research Y.enterocolitica, Y.enterocolitica quantitative research in food,to understand its pollution and resistance gene detection level and conduct further research. |
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