广州市水产品监测中霍乱弧菌分离株的分子特征研究

目的　了解广州市水产品监测中霍乱弧菌分离株的毒力特征,对其菌株进行同源性分析,研究其分子特征及流行病学意义。方法　2 0 0 4年6月采集广州市3家较大的水产品交易市场的海、水产品以及广州以往水型霍乱流行沿海地区的河水和珠江入海口海水,采用聚合酶链反应(PCR)方法对样本检出的霍乱弧菌分离株进行霍乱肠毒素基因(ctx)、小带联结毒素基因(zot)、辅助霍乱肠毒素基因(ace)和毒力协同菌毛蛋白亚单位基因(tcpA)这4种毒力基因的检测,用随机扩增多态性分析(RAPD)结合SPSS软件对以上菌株进行多态性分析,对霍乱弧菌毒力进行快速测定并进行分子分型。结果　共采集海、水产品样本16 0份、水体样本90份,从样本中检出34株霍乱弧菌,其中分离自青蛙12株、虎纹蛙6株、牛蛙5株、养殖水5株、罗氏虾3株,其他3株,根据流行病学调查证实均为海南输入株。毒力基因检测表明,34株霍乱弧菌均未检出ctx和tcpA基因;14株菌(41% )可同时检出ace和zot基因,另有2株菌(6 % )只检出ace基因。所有34株霍乱弧菌的RAPD结果经聚类分析可分为2个聚类群,其中31株属于同一来源,只有3株菌与其他菌株的同源性有差异,但亲缘关系较近。结论　该次水产品监测的霍乱菌株均为非流行株,但仍需加强监测,预防霍乱流行株的出现而导致的霍乱散发和暴发流

Molecular characteristics of vibrio cholera isolated from aquatic products in Guangzhou

Objective To examine the virulence characters and analyze genetic homology of Vibrio cholera(V.cholera)isolated from aquatic products in Guangzhou and to study the molecular characters of these V.cholera and its epidemiological significance. Methods Samples of were collected from several big aquatic products markets in Guangzhou, river water along coastal areas and seawater in the estuary of Pearl River. PCR method was adopted to examine the four virulence genes (ctx, zot, ace and tcpA) from the V.cholera isolates. DNA polymorphism analysis and molecular subtyping were conducted with the combination of randomly amplified polymorphic DNA analysis(RAPD) and SPSS software. Results Altogether, 160 aquatic products and 90 water samples were collected. 34 strains of V.cholera were isolated from these samples and the products were identified to be from Hainan province. Of 34 strains of V.cholera isolates, 34 for both ctx and tcpA negative, 14 (41%) for both ace and zot positive and only 2(6%)for ace positive. 34 strains could be classified into two groups by RAPD analysis, 31 strains had the same source and 3 presented genetic dissimilarity but had close relationship. Conclusion The V.cholera isolates detected in this study were all non-epidemic strains but surveillance should be fortified to prevent the cholera outbreak triggered by the rise of epidemic strains of V. cholera.