中国和新西兰来源生胞梭菌的动物毒性比较及脉冲场凝胶电泳分子分型研究

Comparison of mouse assay and pulsed field gel electrophoresis of Clostridium sporogenes isolated from China and New Zealand

目的分别采用中国和新西兰两国两种不同的试验方法,对我国从相关企业送检的新西兰召回批次浓缩乳清蛋白粉、用问题浓缩乳清蛋白粉生产的婴幼儿配方粉和北京市市售婴幼儿配方粉样品中分离的生胞梭菌,以及新西兰初级产业部从问题批次浓缩乳清蛋白粉分离的11株生胞梭菌对实验动物的毒性作用差异及菌株同源性进行研究。方法将菌株培养物离心过滤除菌后,分别腹腔注射和经口灌胃ICR小鼠,观察小鼠的中毒反应及死亡情况,同时对菌株进行脉冲场凝胶电泳(PFGE)分子分型。结果所有菌株培养物腹腔注射小鼠后,小鼠均出现呼吸急促继而猝死的中毒表现,死亡时间多在染毒后10 min内,而经口灌胃小鼠无中毒和死亡;PFGE结果显示,虽然来源不同,但从问题批次浓缩乳清蛋白粉及其相关产品中分离的10株生胞梭菌均为同一PFGE型,而分离自北京市市售婴幼儿配方粉的1株生胞梭菌为另一PFGE型。结论 10株分离自问题批次浓缩乳清蛋白粉及以其为原料生产的婴幼儿配方奶粉的生胞梭菌致动物中毒和死亡表现无差别,且10株生胞梭菌均为同一PFGE型,说明菌株来自同一污染源。

Objective To compare the toxic effect and pulsed field gel electrophoresis（ PFGE） of 11 Clostridium sporogenes isolates recovered from whey protein concentrate（ WPC） suspected to be contaminated with Clostridium botulinum,powdered infant formula（ PIF） made from WPC and PIF not related to WPC collected in New Zealand and China. Methods Broth cultures of all C. sporogenes isolates were centrifuged and filtered. The supernatants were orally administered and intraperitoneally injected to ICR mice,respectively. The clinical manifestations of mice were recorded.All isolates were subjected to PFGE analysis and the PFGE patterns were interpreted. Results Mice receiving intraperitoneal injection of the culture supernatant of all 11 C. sporogenesisolates were dead. The most important poisoning symptoms included irritable,hair arched,shortness of breath followed by sudden death within 10 min. No poisoning and deaths occurred in mice with oral administration of the cultures. PFGE analysis revealed that 7 isolates from China and 3isolates from New Zealand isolated from WPC and its products share the same PFGE profiles. Different PFGE profile was found in 1 isolate from PIF not related to WPC. Conclusion No difference in toxic effect of the culture supernatant produced by 10 C. sporogenes isolated from WPC and its products which collected in China and New Zealand was observed.The results suggested that WPC contaminated with C. sporogenes detected in both China and New Zealand may be from the same sources,owing to the same PFGE profiles in C. sporogenes from both countries were found.