耐甲氧西林金黄色葡萄球菌耐药表型及基因的研究

Study on drug-resistant phenotypes and genes of methicillin-resistant Staphylococcus aureus

目的研究耐甲氧西林金黄色葡萄球菌(methicillin resistant staphylococcus aureus,MRSA)的耐药表型及耐药基因,为医院感染的防治提供参考及依据。方法选取2018年3月—2020年9月临床感染患者送检标本中分离得到,通过细菌药敏试验法确定为MRSA的90株菌株,根据美国临床实验室标准化委员会(NCCLS)对细菌药敏的操作规程以及实时荧光定量聚合酶链反应(PCR)法分析金黄色葡萄球菌的耐药表型与耐药基因。结果MRSA耐药率50%以上的有青霉素、头孢西丁、克林霉素、红霉素、环丙沙星、甲氧苄氨嘧啶、庆大霉素、左氧氟沙星、四环素和利福平,其中对头孢西丁、青霉素及克林霉素的耐药率为100%;耐药率50%以下的有氯霉素、磺胺甲恶唑、复方新诺明、奎奴普丁/达福普汀、莫西沙星、吠喃妥因、利奈唑胺、万古霉素和替加环素,其中对万古霉素及替加环素的耐药率为0;MRSA耐药表型Ⅰ类7.8%,Ⅱ类41.1%,Ⅲ类50.0%,Ⅳ类56.7%,Ⅴ类70.0%,Ⅵ类96.7%,Ⅶ类2.2%;耐药基因结果最高的是mecA,阳性88株,耐药率97.8%;其余基因msrB 82株(91.1%),msrA 80株(88.9%),ermA 56株(62.2%),ermB 54株(60%),ermC 26株(28.9%),tetM 17株(18.9%),tetK 14株(15.6%),vanA与vanB均为0株。结论MRSA对大部分抗菌药物有较高的耐药率,对万古霉素和替加环素敏感;主要耐药表型为Ⅵ型、Ⅴ型和Ⅳ型,主要耐药基因为mecA、msrB和msrA。

Objective To study the drug resistance phenotype and gene of MRSA,and to provide reference and basis for the prevention and treatment of hospital infection.Methods Totally 90 strains of MRSA were identified by bacterial drug sensitivity test.The drug resistance phenotype and gene of Staphylococcus aureus were analyzed according to the operation procedures of NCCLS and PCR.Result The resistance rate of MRSA is more than 50%penicillin,cefoxitin,clindamycin,erythromycin,ciprofloxacin,trimethoprim,gentamicin,levofloxacin,tetracycline and rifampicin.The resistance rate of cefoxitin,penicillin and clindamycin is 100%;The resistance rates of less than 50%are chloramphenicol,sulfamethoxazole,compound trimethoprim,quinupridine/dalfopristin,Moxifloxacin,venantoin,linezolid,vancomycin and tigecycline,among which the resistance rate to vancomycin and tigecycline is 0;MRSA drug-resistant phenotype classⅠ7.8%,ⅡClass 41.1%,ClassⅢ50.0%,ClassⅣ56.7%,ClassⅤ70.0%,ClassⅥ96.7%,ClassⅦ2.2%;the highest resistance gene result is mecA,with 88 positive strains,with a drug resistance rate of 97.8%;other genes msrB 82 strains(91.1%),msrA 80 strains(88.9%),ermA 56 strains(62.2%),ermB 54 strains(60%),ermC 26 strains(28.9%),tetM 17 strains(18.9%),tetK 14 Strains(15.6%),vanA and vanB are 0 strains.Conclusion MRSA has high resistance rate to most antibiotics,and is sensitive to vancomycin and tegacyclin.The main drug resistance phenotypes are typeⅥ,ⅤandⅣ,and the main drug resistance genes are MECA,MsrB and MsrA.