Nuc和mecA基因在金黄色葡萄球菌及其甲氧西林耐药性检测中的初步应用

Preliminary application of nuc and mecA Genes in the detection of Staphylococcus aureus and resistant to methicillin

目的为获得金黄色葡萄球菌对甲氧西林的耐药信息,评估通过PCR扩增nuc基因、mecA基因检测金黄色葡萄球菌及其甲氧西林耐药性的可行性。方法收集获得63株临床分离鉴定的金黄色葡萄球菌,采用传统药敏检测方法进行菌株药敏测试;再用PCR方法检测菌株是否携带nuc基因和mecA基因,以传统药敏检测结果为参照,评估用PCR扩增技术检测金黄色葡萄球菌及其甲氧西林耐药性的可行性。结果 1.样本菌株中有24株为耐甲氧西林金黄色葡萄球菌(Methicillin-resistant Staphyococcus aureus,MRSA),39株为甲氧西林敏感的金黄色葡萄球菌(Methicillin-sensitive Staphyococcus aureus,MSSA)。来自重症医学科的分离株中MRSA数量较多。2.样本菌株nuc基因携带率为85.7%,其中nuc基因在MRSA菌株中的携带率为87.50%,在MSSA菌株中携带率为84.62%;3.样本菌株mecA基因的携带率为19.05%,其中MRSA菌株的mecA基因携带率为50.0%,MSSA中均不携带mecA基因。来自重症医学科的MRSA中同时携带mecA基因和nuc基因的比例为77.78%。结论用PCR技术检测nuc基因、mecA基因来快速鉴定金黄色葡萄球菌及其甲氧西林耐药性可能存在一定比例的误诊结果。

Objective To explore the resistance of Staphylococcus aureus（S.aureus）to methicillin, and to evaluate the credibility of nuc gene and mecA gene amplification by PCR in the detection of S.aureus and its methoxicillin resistance. Methods Sixty three S.aureus isolates were collected from a hospital in SHIHEZI City, XINJIANG. Phenotypic Kirby-Bauer method was employed to confirmed the antimicrobial susceptibility of all the subjected isolates. The frequency of nuc gene and mecA gene in 63 S.aureus isolates were determined by polymerase chain reaction（PCR）. The usefulness of nuc gene and mecA gene in the detection of S.aureus and determining the resistance of S.aureus to methicillin was appraised with referring to the traditional methods. Results MRSA（methicillin-resistant S.aureus） isolates were found in 38.10%（24/63） of the total clinical isolates of S.aureus. More of MRSA clinical isolates of the total experimental samples were from the intensive care unit. The frequency of nuc gene was 85.7% in total clinical isolates, and nuc gene carrying rate of MRSA strains was 87.50%, while carrying rate of MSSA strains was 84.62%; The frequency of mecA gene was 19.05% in total clinical isolates, twelve out of the 24 MRSA isolates（50%） were mecA negative,whereas all the 39 MSSA（methicillin sensitive S.aureus） were mecA negative.The proportion of MRSA strains carrying both mecA and nuc genes from the intensive care unit was 77.78%. Conclusion It will produce a certain extent of misdiagnosis result if the criterion for identifying Staphylococcus aureus and MRSA only depend on amplifying the nuc gene and mecA gene by PCR.