2014年上海市嘉定区副溶血性弧菌分子流行病学分析

Epidemic Status of Vibrio parahaemolyticus in Shanghai Jiading District,2014

目的了解上海市嘉定区副溶血性弧菌腹泻患者和食品分离株的血清型、毒力基因和分子分型特征及其流行状况。方法对2014年分离自腹泻患者和食品的菌株进行血清分型,以PCR检测菌株的毒力基因tdh和trh及大流行株分子标识GS-PCR和orf8基因,通过PFGE分型分析菌株间的遗传关系。结果嘉定区副溶血性弧菌导致的腹泻病例主要集中在5~10月份,高峰出现在8月份,患者年龄分布呈双峰现象,女性感染者中检出弱产毒或不产毒菌株的比例高于男性。腹泻患者分离株中居前7位的血清型分别为O3：K6、O4：K9、O4：K8、O4：K68、O4：K12、O1：KUT、O3：KUT,产毒株占92.3%,流行株占61.9%,主要以O3：K6为主,orf8基因阴性流行株约占流行株的20.1%。323株副溶血性弧菌分为121个PFGE型,大流行株之间遗传距离更为接近,均处于同一聚类单元;非流行株构成复杂,形成以O4：K8、O4：K9、O4：K12、O3：K29（O3：KUT）为中心的4个聚类单元,且与大流行株距离较远,非流行株之间在PFGE条带上差异也较大。食品分离株均为非产毒株,未发现患者分离株和食品分离株具有相同的PFGE型,且未见形成明显的PFGE聚类单元。结论副溶血性弧菌是嘉定区重要的腹泻病原,其感染控制应以大流行株和产毒株为主,食品监测应充分考虑副溶血性弧菌在病例中的分布情况。

Objective The main purpose of this research is to describe the character of V. parahaemolyticus from sero- types, toxin genes and molecular features,which isolated from diarrhea cases and food in Shanghai Jiading district and its epidemic status. Methods All isolates tested were isolated from diarrhea cases and food by culture method in 2014, and GS-PCR was used to recognize pandemic strains by detecting specific sites in toxR-S genes. Toxin genes tdh and trh were tested with PCR after isolates were serotyped by slide agglutination with O and K Antiserum. Specific bacterial phage were tested by detecting its specific ORF （orfg）. Genome DNA were digested with Restriction enzyme NotI and pulsed field gel electrophoresis was used to produce fingerprint patterns of isolates which was analyzed and clustered in Bionu- merics to show the genetic relationship between isolates. Results Most cases infected by VP were in May to October, accounting for 95.2% in all cases, and the peak was in August reached 27.1% of all cases. All ages of adults could be in- fected but cases from 20--39 and 50--69 years old developed two peaks according to the cases distribution on age. Com- pared with male, female were more likely to be infected by non- or low-virulent isolates which had no virulence gene or just trh gene . The first 7 serotypes in cases were O3：K6（56.4%） , O4：K9（11.7%）, O4：K8（7.3%）, O4：K68（4.4%） , 04 ： K12 （4. 4 %/00 ）, O1 ： KUT （4. 4 %）, 03 .. KUT （4. 0 % ）, and virulence strains were 92. 30%, pandemic strains were 61.9%, and the dominant serotype was O3：K6. In pandemic strains, 20.1% were orf8 negative. 323 isolates were dis- tributed into 121 PFGE types, pandemic strains formed single complex with less than 7 different bands between each two connected isolates, non-pandemic Strains had more complicated PFGE pattern and all were distinct from pandemic ones. 4 non-pandemic related complex were formed around 04 ：KS, 04 ：K9, 04 ..K12, 03 ：K29 （O3 ：KUT） isolates. All food iso- lates were non-virulent and non-pandemic stains No PFGE pattern of food isolates was found to be same with that found in cases with obvious complex. Conclution Vibrio parahaemolyticus is one of the important diarrhea pathogen in Jiading district, and its control should focus on the pandemic strains and virulent strains. Distribution of different types among the patients should be considered during the tset and surveillance of food.