食品中大肠杆菌O157∶H7快速分离培养方法的研究

为检测食品中大肠杆菌O15 7∶H7,本研究通过优化培养基成份和筛选选择性抑菌物质设计了一种选择性分离鉴别培养基 ,CTV MUG RSMAC琼脂。使用该培养基不仅可有效抑制杂菌的生长 ,还能同时鉴定大肠杆菌O15 7∶H7的三种主要生化特征———不发酵山梨醇、不发醇鼠李糖、不分解MUG ,可避免漏检发酵山梨醇的大肠杆菌O15 7∶H7变异株。样品用选择性增菌肉汤 42℃培养过夜后 ,在CTV MUG RSMAC平板上划线接种 ,37℃培养 2 4小时 ,挑选特征菌落做O15 7、H7抗血清凝集试验和肠杆菌科主要生化试验 ,整个程序可在 3天内完成。检测了 12 6份食品样品 ,结果检出 3份阳性 ,与用FDA方法的检测结果一致。

Development of a rapid separating incubation method for detection of Escherichia coli O157∶H7 in food

To detect Escherichia coli O157∶H7 in food, a selective and differential medium, CTV|MUG|RSMAC agar, was designed. Using this medium, the growth of most interfering organisms could be inhibited, and three main biochemical characteristics, including sorbitol|negative, rahmnose|negative and MUG|negative, to identify E.coli O157∶H7 could also be simultaneously recognized. Sorbitol|positive aberrance strains of E.coli O157∶H7 could be distinguished on the medium. The procedure of detecting food sample includes adding sample to selective broth and incubating overnight at 42℃, streaking the inoculum to CTV|MUG|RSMAC agar and incubating at 37℃ for 24h, and picking the typical colonies to react with sera for O157 and H7 antigens, and then take biochemical tests. The procedure could be finished within 3 days. This method has been applied to 126 food samples, and E.coli O157∶H7 was detected from 3 samples. The results were in coincidence with those using FDA method.