引起食物中毒副溶血性弧菌的病原学鉴定

Etiological identification of Vibro parahaemolyticus causing food poisoning

目的分离食物中毒患者粪便及食物加工工具样本中的病原菌,对分离菌株进行表型和毒力基因鉴定。方法采用TCBS平板法分离食物中毒样本中的病原菌。采用细菌系统鉴定方法,确定所分离的副溶血性弧菌(Vibrio parahaemolyticus,Vp)生化反应特性和血清型。采用PCR检测Vp分离株的种属特异基因、直接耐热溶血素毒力基因(tdh)和直接耐热相关溶血素毒力基因(trh)。采用K-B纸片法检测Vp分离株对14种抗生素的敏感性。结果从1例携带者和3例病人粪便标本中分离出4株Vp,从2份食物加工工具样本中分离出2株Vp。6株Vp分离株均属于含Vp种属特异基因的O1∶K56血清型,tdh基因阳性但trh基因阴性。6株Vp分离株生物学性状和药敏试验结果一致。结论tdh+/trh-O1∶K56血清型Vp是引起本次食物中毒的病原菌。

In the present study, the etiological identification of Vibrio parahaemolyticus causing food poisoning was performed, including biochemical identification, serotyping, virulence associated genotyping and drug susceptibility testing. The TCBS plate was used to isolate the suspicious pathogenic bacteria causing food poisoning from stool specimens and food processing tools Biochemical reactive characteristics and serotype of isolates were investigated with the systemic identification methods. Meanwhile, PCR assay was undertaken to detect the genus-specific genes of V. parahaemolyticus, such as virulence associated gene tdh coding direct thermostable haemolysin （TDH） and trh coding TDH-related haemolysis. KB slip method was used to determine the drug susceptibility of isolates to 14 antibiotics. As a result, 6 strains of Vibro. haernolyticus were isolated, including 3 strains from stool specimens of patients, one strain from carriers and 2 strains from food processing tools. All these 6 strains displayed typical biochemical reactions and belonged to serotype O1：K56 with Vp-genus specific genes in which tdh gene appeared to be positive, but no trh gene was detected. They displayed a positive reaction in haemolysis test and were sensitive to 10 antibiotic, but resistant to 4 antibiotics. In addition, they were all virulent to mice. From these observations, it is evident that the rdh＋/trh O1 ：K56 serotype V. parahaernolyticus is responsible to the outbreak of food poisoning events.