重症监护病房耐甲氧西林金黄色葡萄球菌基因同源性分析

Gene homology analysis on methicillin resistant Staphylococcus aureus isolated in intensive care unit

目的对重症监护病房(ICU)感染患者和环境监测分离出的耐甲氧西林金黄色葡萄球菌(MRSA)进行耐药性及基因同源性进行分析。方法对医院ICU医务人员手及高频接触的物品表面进行采样,对感染患者标本进行细菌培养,菌株采用Vitex 2 Compact微生物鉴定药敏系统进行检测,并用肠杆菌科基因间重复序列的聚合酶链反应(ERIC-PCR)对其进行基因分型,采用NTSYS-PC 2.0软件对ERIC-PCR扩增产物进行聚类分析。结果 ICU感染患者标本中有33株金黄色葡萄球菌,16株为MRSA,其检出率为48.48%,ICU医务人员手及环境表面检出6株金黄色葡萄球菌,5株为MRSA,其检出率为83.33%。21株MRSA对万古霉素、利奈唑胺、替考拉宁耐药率为0,对青霉素耐药率为100%,对环丙沙星、红霉素、左氧氟沙星等耐药率超过了80.00%;ERIC-PCR电泳结果显示,最大的分子质量约为450 bp,最小的分子质量约为100 bp,带型各不相同;对21株MRSA扩增产物进行聚类分析,DNA同源性在46.00%~67.00%之间,同源性在68.00%时可分为3个大类,第1、2、3、4、5、6、9、11、13、17菌株亲缘关系较近。结论 ICU临床分离出的MRSA呈多重耐药,临床医生应根据药敏结果合理用药;ICU环境分离出的MRSA也呈现多重耐药,与临床分离株耐药表型有一定的同源性,但基因同源性关联不大;ICU环境物体表面存在MRSA感染风险。

Objective To understand the drug susceptibility and gene homology of methicillin-resistant Staphylococcus aureus（ MRSA） isolates from the patients and environmental samples in intensive care unit（ ICU）. Methods The swabs of medical personnel hands and equipment surfaces frequently contacted in ICU were collected and ICU patients＇ clinical samples were taken for the culture of bacteria. The identification and drug susceptibility of the strains were tested with Vitex Compact system,the homology was detected by using enterobacterial repetitive intergenic sequence（ ERIC）-PCR,the cluster analysis was performed with software NTSYS-PC 2. 0. Results A total of 33 strains of S. aureus was detected from ICU patients,16 strains were identified as MRSA,the positive rate was 48. 48%. Six strains of S. aureus were isolated from ICU medical personnel hands and environment,in which 5 were MRSA（ 83. 33%）. The resistant rates of 21 strains of MRSA to vancomycin,linezolid,teicoplanin were 0. The resistant rate to penicillin was 100%,the resistant rates to ciprofloxacin,erythromycin and levofloxacin were 80%; ERIC-PCR electrophoresis results showed that the maximum molecular band was about 450 bp,the smallest molecule was about 100 bp,with different profiles for 21 different strains of MRSA. The homologies of 21 strains ranged from 46. 00% to 67. 00%,when homology was 68. 00%,it could be divided into 3 categories,the strain 1,2,3,4,5,6,9,11,13 and 17 had close relation. Conclusion The clinical MRSA isolates in ICU were multi drug resistant,clinicians should use antibiotics according to the drug susceptibility test results; the MRSA isolates in ICU environment also showed multi drug resistance,and the resistant phenotypes had certain homogeneity with clinical isoaltes,but the gene homology had no obvious relation. The environment of ICU was a MRSA infection source.