一株不典型金黄色葡萄球菌的鉴定分析

目的:对某进出口公司送检的一批含乳加工食品进行金黄色葡萄球菌检验时检出的一株可疑菌株进行分析、鉴定和总结,避免发生由于不典型的金黄色葡萄球菌漏检造成的食品安全事件.方法:按GB 4789.10-2010《食品微生物学检验:金黄色葡萄球菌检验》进行取样和增菌,从BP平板分离出的可疑菌落经血琼脂平板溶血试验、革兰氏染色镜检及血浆凝固酶试验等进行分析,随后利用全自动微生物鉴定仪及实时荧光聚合酶链式反应(PCR)法进行比对分析和确认.结果:与金黄色葡萄球菌标准菌株相比较:该菌株菌落直径较大,在血琼脂平板上呈白色菌落,溶血现象不明显,血浆凝固酶结果呈阳性；全自动微生物鉴定仪及实时荧光PCR鉴定金黄色葡萄球菌呈阳性.结论:经分析确认,检出可疑菌落为一株不典型金黄色葡萄球菌.实时荧光PCR法能够快速、准确地检出金黄色葡萄球菌,有效缩短检测周期.多种检测方法结合,可有效克服漏检的可能.

Identification and Analysis of a Nontypical Staphylococcus aureus Strain

A suspected strain isolated from a batch of processed dairy products submitted by an import/export enterprise to our laboratory for the detection of Staphylococcus aureus was identified and analyzed. According to the Chinese national food safety standard Food Microbiological Examination: Staphylococcus aureus (GB 4789.10–2010), sampling and enrichment were performed, the suspected colony isolated on BP plates was subjected to hemolysis test on blood agar plates, microscopic observation after Gram staining, and plasma coagulase test before alignment, analysis and confirmation using a fully automated bacterial identification system and PCR. The suspected strain had a larger colony diameter compared with the reference strain of Staphylococcus aureus, showed white colonies on blood agar plates with no obvious hemolysis phenomenon but positive plasma coagulase test results, and was identified using a fully automated bacterial identification system and PCR as a nontypical strain of Staphylococcus aureus. In conclusion, real-time PCR enables rapid and accurate detection of Staphylococcus aureus while substantially shortening the detection time, and the possibility of missing the pathogen can be effectively overcome by combined use of different detection methods.