耐甲氧西林金黄色葡萄球菌SCCmec基因分型及耐药性分析

Genotyping and Drug Resistance Analysis of Methicillin-resistant Staphylococcus Aureus SCCmec

关键词:  耐甲氧西林金黄色葡萄球菌  甲氧西林耐药决定子A  葡萄球菌染色体mec基因盒  基因分型  耐药性

Key words:  methicillin-resistance Staphylococcus anreus  methicillin resistance determinant A(mecA)  Staphylococcal aureus cassette chromsome mec  genotyping  drug resistance

摘要:

目的 分析台州市中西医结合医院临床分离的耐甲氧西林金黄色葡萄球菌（methicillin-resistant Staphylococcus aureus，MRSA）SCCmec基因分型及耐药情况，为临床MRSA感染的诊治提供参考。方法 以笔者所在医院2017年1月—2018年12月从临床各类标本中分离的297株金黄色葡萄球菌（Staphylococcus aureus，SA）为研究对象。根据对头孢西丁的药敏试验筛选出MRSA菌株，并采用PCR对其进行MRSA及SCCmec鉴定及基因分型；采用K-B纸片扩散法分析不同SCCmec基因型菌株耐药情况。结果 297株SA经MRSA初筛试验结果127株为阳性，初筛试验阳性率为42.76%，127株初筛阳性菌株再经mecA基因检测有121株阳性，MRSA确证试验阳性率为40.74%，表型与基因型检测符合率为95.28%。MRSA的SCCmec分型： 77株为SCCmecⅢ型，34株为SCCmecⅡ型，3株为SCCmecⅣ型，7株用此法无法分型；药敏试验显示： SCCmecⅡ型与SCCmecⅢ型菌株对万古霉素、替考拉宁100%敏感，相反对β-内酰胺类抗菌药物100%耐药。SCCmecⅢ菌株对大环内酯类、喹诺酮类、四环素类和林可霉素类耐药率显著高于SCCmecⅡ菌株，差异有统计学意义。结论 笔者所在医院临床各类标本分离的MRSA以SCCmecⅢ型为主要流行菌株，MRSA耐药情况较为严重，表现为多重耐药现象。

Abstract:

OBJECTIVE To analyse genotyping and drug resistance of methicillin-resistant Staphylococcus aureus (MRSA) SCCmec isolated in Taizhou Traditional Chinese and Western Medicine Hospital, and to provide reference for diagnosis and treatment of clinical MRSA infection. METHODS The 297 strains of Staphylococcus aureus(SA) isolated from clinical specimens in hospital where author work in were studied from January 2017 to December 2018, and MRSA were screened according to the drug sensitivity test of cefoxitin. The MRSA and SCCmec were identified and genotyped by PCR. The resistance of different SCCmec genotypes was analyzed by K-B disk diffusion method. RESULTS The 127 strains were positive by MRSA screening test in 297 SA strains. The positive rate of primary screening test was 42.76%. There were 121 positive strains in 127 primary screening positive strains by mecA gene test. The positive rate of MRSA confirmation test was 40.74%, and the coincidence rate of phenotype and genotype detection was 95.28%. SCCmec typing of MRSA:77 strains were SCCmec type Ⅲ, 34 strains were SCCmec type Ⅱ, and 3 strains were SCCmec type Ⅳ. Seven strains could not be classified by this method. Drug susceptibility test showed that SCCmec type Ⅱ and SCCmec type Ⅲ strains were 100% sensitive to vancomycin and teicoplanin, but 100% resistant to beta-lactam antibiotics. The resistance rate of SCCmec type Ⅲ strain to quinolones, macrolides, tetracyclines and lincomycin was significantly higher than that of SCCmec type Ⅱ strain, and the difference was statistically significant. CONCLUSION The main epidemic strain of MRSA isolated from clinical specimens in hospital where author work in is SCCmec type Ⅲ. The drug resistance of MRSA is serious, manifesting as multi-drug resistance.