大肠埃希氏菌O157:H7能力验证结果分析及讨论

Analysis and Discussion on the Verification Results of Escherichia coli O157:H7

目的:从FAPAS能力验证样品(沙拉)中分离、鉴定大肠埃希氏菌O157:H7,分别判定两个样品是否检出目标菌。方法:本实验采用国家标准《食品安全国家标准 食品微生物学检验 大肠埃希氏菌O157:H7/NM检验》(GB 4789.36—2016)第一法和基质辅助激光解吸电离飞行时间质谱法(Matrix-assisted Laser Desorption Ionization-time of Flight Mass Spectrometry,MALDI-TOF MS)对能力验证样品进行鉴定。结果:样品M248d11A中未检出大肠埃希氏菌O157:H7,鉴定干扰菌株为大肠埃希氏菌;样品M248d11B中检出大肠埃希氏菌O157:H7,结果为满意。结论:在进行能力验证实验中,为避免交叉污染,尽量选择不同生物安全柜进行试验;MALDI-TOF MS对于血清型的鉴定可以参考聚类树状谱系图,但不建议作为判定的主要依据。

Objective:To isolate and identify Escherichia coli O157:H7 from FAPAS ability verification sample (salad),and determine whether the target bacteria are detected in the two samples.Method:The first method of GB 4789.36—2016 and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) were used to identify the ability verification samples.Result:Escherichia coli O157:H7 was not detected in sample M248d11A,and the interfering strain was identified as Escherichia coli.Escherichia coli O157:H7 was detected in sample M248d11B.Conclusion:In the capacity verification experiment,in order to avoid cross contamination,different biosafety cabinets should be selected as far as possible;MALDI-TOF MS can refer to the clustering tree pedigree for the identification of serotypes,but it is not recommended as the main basis for judgment.