一株金黄色葡萄球菌小菌落突变株的分离鉴定

Isolation and identification of a Staphylococcus aureus small colony variants

【目的】由于金黄色葡萄球菌(金葡菌)小菌落突变株(small colony variants,简称SCVs)可引起持续复发性感染,且对氨基糖苷类有抗药性,在临床诊断和治疗上造成很大的困扰。我国国内尚无金葡菌SCVs的报道,本研究旨在分离鉴定出金葡菌SCVs菌株,为国内进行SCVs的相关研究提供生物学材料。【方法】通过细菌的形态鉴定、种特异性基因(nuc)的PCR扩增鉴定以及系列生化实验,从人源、动物源及环境源共104株金葡菌分离株中筛选得到金葡菌SCVs,并通过甲萘醌、硫胺素、胸腺嘧啶和血红素等补偿实验加以验证。【结果】获得一株来自环境源的金葡菌SCVs分离株,命名为CDC54,该菌株含有金葡菌种特异性基因nuc,主要表现为菌落细小,色素形成减少,凝固酶活性下降,对甘露醇的发酵作用减弱,溶血活性降低及对氨基糖苷类抗生素有抗药性。【结论】成功分离鉴定出一株金葡菌SCVs,为国内开展SCVs相关疾病的防控和进一步研究SCVs的相关致病机理奠定基础。

[Objective] Staphylococcus aureus small colony variants（S.aureus SCVs） could lead to persistent,recurrent infection with the characteristics of aminoglycosides antibiotics resistance,making them a big challenge for clinical diagnosis and therapy.We aimed at isolating and identifying isolates of S.aureus SCVs and providing the biological material of SCVs study in China.[Methods] The combination assays of observing colony phenotype,identification of the species-specific gene nuc of S.aureus by PCR amplification and a series of biochemical tests were conducted on 104 clinical isolates originally isolated fromhuman, cow and environment. The suspected isolates were confirmed as S. aureus SCVs by complementation assay with supplementation of menadione, thiamine, thymine and haemin. [ Results] One of the isolates from environment was identified as SCVs, named CDC54 with the species-specific gene nuc of Staphylococcus aureus （S. aureus） confirmed by PCR amplification, whose major phenotypes included smaller colony, decreased pigmentation, decreased coagulase, reduced fermentation of lactose, decreased haemolytic activity, increased resistance to aminoglycosides. [ Conclusion] The CDC54 will play an important role in studying prevention, control and pathogenesis for S. aureus SCVs infection.