食品分析能力评估计划能力验证样品中大肠埃希氏菌O157:H7的分离鉴定及质量控制

Isolation and detection of Escherichia coli O157:H7 and quality control in food analysis performance assessment scheme proficiency test

目的从食品分析能力评估计划能力验证样品沙拉中分离、鉴定大肠埃希氏菌O157:H7,判断2份样品是否有检出。方法参照GB 4789.36-2016《食品安全国家标准食品微生物学大肠埃希氏菌O157:H7/NM》进行检测,将VITEK 2 compact生化结果符合的菌株进行O157和H7抗原血清学鉴定。结果样品编号M221d11B检出大肠埃希氏菌O157:H7,样品编号M221d11A未检出大肠埃希氏菌O157:H7。测试样品的背景干扰菌是成团泛菌和铜绿假单胞菌。结论取得满意的能力验证结果需要注意以下因素:培养基试剂的质量、样品之间的交叉污染、样品的正确复苏和制备、菌落特征的识别以及干扰菌株的排查等。

Objective To isolate and identify Escherichia coli O157：H7 in salad for food analysis performance assessment scheme （FAPAS） proficiency test. Methods According to GB 4789.36-2016 National food safety standard-Food microbiological examination： Escherichia coli O157：H7/NM, 2 samples were detected. Typical strains were tested with VITEK 2, and serological tests were proceeded afterwards. Results Escherichia coli O157：H7 was detected in the sample M221d11B, and not detected in the sample M221d11A. Organisms presented in FAPAS were Pantoea agglomerans and Pseudomonas aeruginosa as background flora. Conclusion The satisfactory result needs to pay attention to the following factors： quality of the culture medium, cross contamination, correct sample preparation, identification of colony characteristics, and screening of interfering strains, etc.