苯唑西林敏感耐甲氧西林金黄色葡萄球菌(OS-MRSA)研究进展

Research progress of oxacillin-susceptible methicillin-resistant Staphylococcus aureus

金黄色葡萄球菌(Staphylococcus aureus,SA)是导致医院内感染及社区获得性感染的一种常见病原菌,可引起宿主不同部位的感染,感染类型多样。耐甲氧西林金黄色葡萄球菌(methicillin resistant Staphylococcus aureus,MRSA)呈现对多种类型抗菌药物的耐药特征,其在不同国家和地区的检出率和流行特征存在明显差异。随着对MRSA耐药性和耐药机制研究的不断深入,一种具有特殊耐药特征的MRSA亚群逐渐被报道,即苯唑西林敏感的耐甲氧西林金黄色葡萄球菌(oxacillin-susceptible methicillin-resistant Staphylococcus aureus,OS-MRSA)。OS-MRSA典型特征为携带抗药性基因mecA,但其对苯唑西林的MIC值较低(通常<4mg/L)。由于目前临床实验室主要采用苯唑西林和或头孢西丁药敏试验方法来区分MRSA及甲氧西林敏感金黄色葡萄球菌(MSSA),而很少应用基因检测方法(mecA基因)进行检测或确认,因此OS-MRSA常被错误报告为MSSA,临床依据药敏报告进行抗感染治疗,常导致治疗失败及患者病死率的增加。此外,OS-MRSA菌株在不同国家和地区人群分离率及其分子流行病学特征存在较大差异。因此,本文将从分子流行病学、实验室检测方法、耐药机制、毒力特征及临床治疗等5个方面对OSMRSA的最新研究进展进行综述。

Staphylococcus aureus is a common pathogen causing nosocomial and community acquired infections,which can cause various types of infections.Methicillin-resistant Staphylococcus aureus exhibits resistance to many types of antibiotics,and its incidence rates and epidemic characteristics in different countries and regions varied significantly.With continuous exploration on the resistance features and resistance mechanism of MRSA,a subpopulation of MRSA with special resistance characteristics has been gradually reported around the world,which is called oxacillin-sensitive methicillin resistant Staphylococcus aureus(OS-MRSA).The characteristics of OS-MRSA is positive with resistance gene mecA,but its MIC value for oxacillin is low(usually under 4mg/L).However,oxacillin and or cefoxitin sensitivity testing methods were normally used in clinical laboratories to distinguish MRSA and methicillin-sensitive Staphylococcus aureus(MSSA),while genetic testing method(mecA gene detection)was rarely used.OS-MRSA is often incorrectly reported as MSSA,which may lead to failure of anti-infection therapy and increased mortality of patients,since anti-infective treatment is often performed based on drug sensitivity testing results.In addition,the isolation rates and molecular epidemiological characteristics of OS-MRSA strains in different countries and regions are significantly different.Therefore,this review summarizes the latest research progress of OS-MRSA from the following five aspects,molecular epidemiology,laboratory testing methods,drug resistance mechanism,virulence characteristics,and clinical treatment.