一株发酵乳糖不产气大肠埃希氏菌的分离与鉴定

Isolation and Identification of an Escherichia coli Strain Fermenting Lactose Without Gas Production

为了准确鉴定1株分离自餐饮具的大肠埃希氏菌非典型菌株(发酵乳糖不产气),通过传统分离培养、常规生化试验、微生物鉴定、基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)、多重聚合酶链式反应(multi-PCR)的方法对该菌株进行联合鉴定。结果表明:该菌株乳糖发酵试验及伊红美蓝琼脂(EMB)平板上的菌落形态均有别于典型大肠埃希氏菌,但微生物鉴定、MALDI-TOF MS、多重PCR鉴定结果与标准菌株一致,均显示为大肠埃希氏菌。这说明常规方法检验非典型大肠埃希氏菌有误判风险,建议检验者遇初发酵培养物变浑浊时转接EMB琼脂平板,并辅以微生物自动鉴定仪器或分子生物学方法对可疑菌落进行鉴定,以确保检验结果的准确性。

To accurately identify an atypical Escherichia coli(fermenting lactose without gas production)from catering utensils,traditional isolation and culture,routine biochemical experiments,microbial identification system,matrix assisted laser desorption ionization time of flight mass spectrometry(MALDI-TOF MS),and multiple polymerase chain reaction(multi-PCR)have been jointly used.The results of lactose fermentation experiment and colony morphology of the anaerogenic strain on the eosin-methylene blue agar(EMB)plate have showed its difference from the typical Escherichia coli;however,the results of microbial identification system,MALDI-TOF MS and multi-PCR have consistently confirmed that it is an Escherichia coli.That means the routine method for inspecting atypical Escherichia coli has a risk of misidentification.It is recommended to transfer the primary fermentation culture substance to EMB agar plates when it is becoming turbid,and to supplement the automatic identification system or molecular biology method for the identification of suspicious colonies,ensuring the accuracy of inspection results.