提高食品中阪崎肠杆菌的阳性检出率

Enhance the positive rate in the detection of Enterobacter sakazakii

阪崎肠杆菌对食品的污染具有微量和高度不均一性的特点,使得该菌能“逃避”食品卫生微生物学的检验。以国内生产的婴儿配方乳粉为样品,采用荧光定量PCR法和分离计数法分别进行检验,对影响检出率的主要因素进行比较和讨论。结果表明,样品中的阪崎肠杆菌分离株主要有6种生化型,X-α-GlcA琼脂的选择分离效果优于其它培养基,荧光定量PCR法有一定的假阳性率,同一批次样品不同包装间的个体差异较大,而且在同一样品中,常常会同时检出阪崎肠杆菌的不同的生化型或亚种,要挑取足够多的菌落用于生化鉴定。

A low concentration and unequal distribution present within the powdered formula may escape detection by conventional methods, Both real-time PCIZ method and conventional isolation method are applied for determination of Enterobacter sakazakii in powdered formula sample manufactured in China, and main factors contributed to the positive rate were compared and discussed fully. The results shows that E. sakazakii isolated from samples include 6 bio-types, X-α-Glc agar show better distractive satisfactory than others, false positive results may be obtained by real-time PCR. method, individual difference between packages from the same batch may be great, different bio-types or subspecies may be isolated from even the same package, and more than one colony should be picked for biochemical identification.