耐碳青霉烯类鲍氏不动杆菌的耐药机制及同源性分析

Drug resistance mechanisms of carbapenem-resistant Acinetobacter baumannii and analysis of homology

目的调查医院ICU流行的耐碳青霉烯类鲍氏不动杆菌的耐药机制及其同源性,为临床有效防治提供依据。方法收集北京市海淀医院2011年11月ICU住院患者痰标本分离出的耐碳青霉烯类鲍氏不动杆菌4株,按《全国检验技术操作规程》操作,用全自动微生物分析仪进行细菌鉴定及药敏试验,PCR扩增检测碳青霉烯酶基因,用脉冲场凝胶电泳(PFGE)进行分型,分析其同源性。结果 4株鲍氏不动杆菌中除对头孢哌酮/舒巴坦(2株敏感、2株中度敏感)、磺胺甲噁唑/甲氧苄啶(2株敏感、2株耐药)、阿米卡星(1株敏感、3株耐药)稍敏感外,对其他各种抗菌药物均耐药;4株菌株均携带blaOXA-23-like和blaOXA-51-like基因;PFGE电泳结果显示,4株鲍氏不动杆菌分为A(A1、A2、A3)和B型,其中A型为主要的流行株。结论鲍氏不动杆菌为多药耐药菌株;产碳青霉烯酶OXA-23是该菌对碳青霉烯类抗菌药物耐药的主要机制;同一克隆株在同一病房内传播致交叉感染。

OBJECTIVE To investigate the drug resistance mechanisms of carbapenem-resistant Acinetobacter bau-mannii （CRAB） prevalence in the ICU and analyze the homology so as to provide basis for the effective clinicalprevention and treatment. METHODS Totally 4 strains of CRAB isolated from the sputum specimens of the pa-tients who were hospitalized the ICU of the hospital in Nov 2011 were included in the study, then the bacterial i-dentification and antimicrobial susceptibility testing were carried out by using the automated microbial analyzer ac-cording to national laboratory technical operation requirements, the carbapenemase gene was detected by means ofPCR, and the genotyping was performed to analyze the homology by using pulse-field gel electrophoresis（PFGE）.RESULTS The 4 strains of A. baumannii were resistant to all the antibiotics except for cefoperazone/sulbactam （2strains sensitive,2 strains moderately sensitive）,sulfamethoxazole-trimethoprim （2 strains sensitive, 2 strains re-sistant）, and amikacin （1 strain sensitive, 3 strains resistant）. All the 4 strains of A. baumannii carried the blaOXA-22 and blaOXA-51 genes; the PFGE electrophoresis results showed that the 4 strains of A. baumannii belongedto type A（A1,A2,A3） and B, while type A was the predominant epidemic isolate. CONCLUSION The A, bauman-nii is multidrug-resistant, the production of carbapenemase OXA-23 is the main drug resistance mechanism to carbapenem antibiotics; the spread of the same clone in the same ward may result in the cross infections.