异质性利奈唑胺耐药金黄色葡萄球菌耐药机制研究

Antibiotic resistance mechanism of heterogeneous linezolid-resistant Staphylococcus aureus

目的筛选异质性利奈唑胺耐药金黄色葡萄球菌(heterogeneous linezolid resistant Staphylococcus aureus,hLRSA)并对其耐药机制进行分析。方法采用菌谱分析法筛选hLRSA,琼脂稀释法和E-test法检测MIC值,PCR方法扩增介导利奈唑胺耐药葡萄球菌耐药的cfr基因,同时扩增hLRSA 23S RNA基因并测序,并登陆GenBank,与基因库中金葡菌ATCC29213 23S RNA基因比对。结果 hLRSA检出率为1.26%(2/158);琼脂稀释法和E-test法检测异质性耐药菌株MIC结果基本一致;PCR方法没有检出cfr基因,2株hLRSA 23S RNA基因扩增后测序,与金黄色葡萄球菌23S RNA基因一致性大于99%,其中1株hLRSA 23S RNA基因序列在2474位点出现"G"→"T"点突变,可能与介导hLRSA耐药性有关。结论利奈唑胺在体外对金黄色葡萄球菌具有较强抗菌活性,没有检出利奈唑胺中介或耐药葡萄球菌,hLRSA检出率为1.26%,耐药性可能与其23S RNA发生的点突变有关。

Objective To detect heterogeneous linezolid-resistant Staphylococcus aureus （hLRSA）, and to study its antibiotic resistance mechanism. Method Population analysis was used to detect hLRSA from clinical isolates of Staphylococci, agar dilution method and E-test were used to detect MICs, and PCR was applied to scan cfr gene from hLRSA and to sequence 23S rRNA. Result 2 strains ofhLRSA （out of 158 strains） were detected（l.26%）. Agar dilution method and E-test can get the same relevance ratio. No linezolid intermediate or resistant Staphylococcus aureus was detected, nor cfr gene was found from hLRSA strains by PCR. A G2474T mutation was identified in 23S rRNA of hLRSA isolate.