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目的了解某院重症监护室(ICU)分离的多重耐药鲍曼不动杆菌(MDR-AB)Ⅰ型整合子阳性率,并分析MDR-AB的同源性,探讨Ⅰ型整合子参与耐药、传播的分子机制。方法收集2008年1月—2009年12月该ICU分离的40株MDR-AB,采用K-B纸片扩散法检测其耐药性,聚合酶链反应(PCR)进行Ⅰ类整合子可变区扩增、克隆测序,分析Ⅰ类整合子基因结构。应用脉冲场凝胶电泳(PFGE)分析MDR-AB的同源性。结果 75.00%(30/40)的菌株Ⅰ类整合子阳性,共检测出两种基因盒,分别为aacA4-catB8-aadA1和aacC1-orfX-orfX-orfX’-aad A1。PF-GE结果表明,40株菌分为4个克隆,其中有26株属于B克隆,为主要流行菌株型。结论Ⅰ类整合子在MDR-AB中广泛存在,可能通过水平传播方式在ICU中传播。携带aacA4-catB8-aadA1整合子的MDR-AB引起了ICU鲍曼不动杆菌的流行。
Objective To investigate the positive rate of type Ⅰ integron of multidrug-resistant Acinetobacter baumannii (MDR-AB) isolated from intensive care unit (ICU) in a hospital and to analyze the homology of MDR-AB and explore the role of type Ⅰ integron in drug resistance , The molecular mechanism of communication. Methods Forty MDR-AB isolates isolated from the ICU from January 2008 to December 2009 were collected and tested for resistance by KB disk diffusion method. Group Ⅰ integron variable region amplification was detected by polymerase chain reaction (PCR) , Cloned and sequenced to analyze the class I integron gene structure. The homology of MDR-AB was analyzed by pulsed-field gel electrophoresis (PFGE). Results 75.00% (30/40) of the strains were positive for class Ⅰ integrons. Two gene cassettes were detected, which were aacA4-catB8-aadA1 and aacC1-orfX-orfX-orfX’-aad A1, respectively. PF-GE results showed that 40 strains were divided into 4 clones, of which 26 strains belonged to B clone, which was the main epidemic strain. Conclusions Class I integrons exist widely in MDR-AB and may spread in the ICU through horizontal transmission. MDR-AB carrying the aacA4-catB8-aadA1 integrin elicited the prevalence of Acinetobacter baumannii in the ICU.