Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, China.
Department of Infection Control Center, Xiangya Hospital, Central South University, Changsha, China.
J Clin Lab Anal. 2022 Jan;36(1):e24121. doi: 10.1002/jcla.24121. Epub 2021 Nov 27.
Small colony variants (SCVs) of Staphylococcus aureus (S. aureus) frequently lead to chronic and recurrent infections, but they are always ignored and there are few researches on their clinical isolates. We intended to investigate the prevalence and characteristics of S. aureus SCVs.
None-duplicated S. aureus strains isolated from wound samples were collected from January 2018 to December 2020. The characteristics (i.e. colony morphology, growth rate, coagulase, biofilm formation, and pathogenic characteristics), antimicrobial susceptibilities, and resistance mechanisms of SCVs were also investigated. The genetic background of SCVs was analyzed through staphylococcal protein A (SPA) typing, sequence typing, and pulse field gel electrophoresis (PFGE).
Three SCVs were screened from 278 S. aureus strains (1.1%). They formed pinpoint white colonies on blood agar plates with weak hemolysis. The reproduction speed in liquid medium was very slow for SCVs strains. The coagulase weakened or disappeared, and the ability to form biofilm varied greatly. Only slight inflammation was triggered when wound infected. The SPA typing was t2592, t233, and t023, and the sequence typing was ST88, ST239, and ST965, respectively. The PFGE revealed three SCVs were singletons.
The rate of SCVs in wound sample is low in our hospital, and the formation is associated with the usage of antimicrobial. SCVs grow slowly, and their colony morphology and biochemical characteristics are significantly different from classic S. aureus. SCVs may cause chronic infection and weak inflammation. SCVs form in resistant or susceptible strains, and there is no clonal epidemic in this hospital.
金黄色葡萄球菌（S. aureus）的小菌落变异株（SCVs）常导致慢性和复发性感染，但它们总是被忽视，对其临床分离株的研究甚少。我们旨在调查 S. aureus SCVs 的流行情况和特征。
从 2018 年 1 月至 2020 年 12 月，收集了来自伤口样本的非重复 S. aureus 菌株。还研究了 SCVs 的特性（即菌落形态、生长速度、凝固酶、生物膜形成和致病特性）、药敏性和耐药机制。通过葡萄球菌蛋白 A（SPA）分型、序列分型和脉冲场凝胶电泳（PFGE）分析 SCVs 的遗传背景。
从 278 株金黄色葡萄球菌中筛选出 3 株 SCVs（1.1%）。它们在血琼脂平板上形成针尖状白色菌落，溶血较弱。SCVs 株在液体培养基中的繁殖速度非常缓慢。凝固酶减弱或消失，生物膜形成能力差异很大。当伤口感染时，仅引起轻微炎症。SPA 分型分别为 t2592、t233 和 t023，序列分型分别为 ST88、ST239 和 ST965。PFGE 显示 3 株 SCVs 均为单体。
我们医院伤口样本中 SCVs 的检出率较低，其形成与抗菌药物的使用有关。SCVs 生长缓慢，其菌落形态和生化特征与典型金黄色葡萄球菌有显著差异。SCVs 可能引起慢性感染和轻微炎症。SCVs 可在耐药或敏感株中形成，且本医院未出现克隆性流行。
