3种方法检测食品中致泻大肠埃希氏菌检测能力验证结果分析

Capability verification results and analysis of 3 methods for detecting diarrheagenic Escherichia coli in food

目的提高食品中致泻大肠埃希氏菌的检测能力,促进实验室检测能力的提高。方法参照GB4789.6-2016《食品微生物学致泻大肠埃希氏菌检验》方法进行检测,采用VITEK 2 Compact全自动细菌鉴定系统进行生化鉴定、血清学鉴定,对可疑菌落进行普通PCR确证试验。同时使用多重实时荧光PCR法以及基质辅助激光解析电离飞行时间质谱(matrix-assisted laser desorption ionizationtime-of-flight mass spectrometry,MALDI-TOF-MS)分析鉴定可疑菌落。结果国标法和多重实时荧光PCR法能准确鉴定出目标菌,MALDI-TOF-MS可以检测大肠埃希氏菌,但无法区分致泻大肠埃希氏菌和肠出血性大肠埃希氏菌。结论3种方法各有优劣,同时使用,综合判断,能确保试验结果准确快速。

Objective To improve the ability for the detection of diarrheagenic Escherichia coli in food,and promote the improvement of laboratory testing capabilities.Methods According to GB 4789.6-2016 Food microbiology-Detection of diarrheal Escherichia coli for detection,biochemical identification and serological identification were carried out by VITEK 2 Compact automatic bacterial identification system,and common PCR confirmation test was carried out on suspicious colonies.At the same time,multiple real-time fluorescence PCR and matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF-MS)were used to analyze and identify suspicious colonies.Results The target bacteria could be accurately identified by national standard method and multi-real-time fluorescence PCR method.Escherichia coli could be detected by MALDI-TOF-MS,however,diarrheagenic Escherichia coli and enterohemorrhagic Escherichia coli couldn’t be distinguished.Conclusion The combination and synthetic judgment of the 3 methods can ensure the accuracy of the testing result while each has advantages and disadvantages.