鲍氏不动杆菌医院感染株耐碳青酶烯类药物的耐药机制研究

Mechanism of Carbapenem-resistant Acinetobacter baumannii in Hospital Infection

目的了解医院内获得性耐碳青酶烯类鲍氏不动杆菌(CRAB)的耐药性、同源性、耐药机制。方法采用VITEK-32细菌鉴定仪配套药敏试剂GNS-448进行抗菌药物敏感性试验;采用脉冲场凝胶电泳(PFGE)分析同源性;通过改良三维试验、聚合酶链反应(PCR)、基因测序等方法分析耐药机制。结果7株耐碳青酶烯类鲍氏不动杆菌显示出同样的耐药情况,对13种抗菌药物均耐药,仅头孢哌酮/舒巴坦有一定的敏感性;PFGE结果表明,7株CRAB为同一克隆株;均产不能被克拉维酸和氯唑西林所抑制的酶;PCR扩增产酶基因检测结果以blaPER、blaVEB、blaVIM、blaIMP、blaOXA-24、blaOXA-51、blaOXA-58的特异引物扩增均未出现阳性条带,blaOXA-23群阳性,并经测序证实为blaOXA-23。结论鲍氏不动杆菌的耐药性严重,耐碳青酶烯类鲍氏不动杆菌流行是医院感染所致,CRAB均产OXA-23型碳青酶烯酶。

OBJECTIVE To investigate the resistance, homology and the mechanism of earhapenem-resistant Acinetobacter baumannii （CRAB） in hospital infection. METHODS Seven strains of CRAB collected from hospital. GNS- 448 was made to determine the minimal inhibitory concentrations（MIC） of these strains. The homolgy of the isolates was determined by pulsed field gel electrophoresis（PFGE）. The mechanism of earbapenem-resistantce was typed by three-dimensional test, polymerase chain reaction（PCR）, cloning and sequencing methods. RESULTS There were the same resistance rates of 7 CRAB isolates, only cefoperazone/sulbactam was sensitive, and they had the same type on PFGE pattern. The CRAB isolates produced carbapenemases, that eouldn＇t be inhibited by elavulanie acid and cloxacillin, blaPER, blaVEB, blaVIM, blaIMP, blaOXA-24, blaOXA-51, and blaOXA-58 type genes were all negative, OXA-23 type gene was detected by PCR method. CONCLUSIONS The resistance of A. baumannii is very serious. The CRAB in our hospital is due to nosocomial infection,and all produce OXA-23 type carbapenemases.