耐亚胺培南鲍曼不动杆菌同源性及耐药机制研究

目的调查本院耐亚胺培南鲍曼不动杆菌(IRAB)的分子流行特点,初步研究其对碳青霉烯类抗菌药物耐药的分子机制。方法收集2009年11月至2010年1月不同临床科室分离的IRAB非重复株共54株,用Vitek 2 Compact全自动微生物分析仪进行药敏试验;用脉冲场凝胶电泳(PFGE)分析IRAB的同源性;PCR及DNA测序检测碳青霉烯酶和16S rRNA甲基化酶相关耐药基因型。结果 54株细菌PFGE可分为A、B两个型,其中A型42株,占77.8%,在各科室均有分布,为主要的流行型别;B型10株,占18.5%,仅在神经内、外科的ICU分布。全部54株菌均携带OXA-66基因,53株菌携带OXA-23基因及其上游插入序列ISAba1,41株菌携带16S rRNA甲基化酶armA基因。结论医院临床各科室存在A型IRAB的克隆播散,而B型IRAB仅在神经内、外科ICU流行。OXA-23基因及其上游插入序列ISAba1是最主要的耐碳青霉烯类抗菌药物机制,armA型16S rRNA甲基化酶基因在IRAB中广泛分布。

Homology and resisitance mechanism of imipenem-resistant Acinetobacter baumannii

Objective To investigate the molecular prevalent feature of imipenem-resistant Acinetobacter baumannii(IRAB) in our hospital,and analyze its molecular mechanism of resistance to carbapenems.Methods Fifty-four non-repetitive IRAB strains isolated from different clinical departments were collected from November 2009 to January 2010.The antimicrobial susceptibility test was performed with Vitek-2 Compact system.The homology of IRAB was analyzed by pulsed field gel electrophoresis(PFGE).The related resistance genetypes of carbapenemase and 16S rRNA methylase were detected by PCR and DNA sequencing.Results Fifty-four IRAB strains were distributed into type A and B according to PFGE results.Among the 54 strains,42 strains(77.8%) belonged to type A which was the main prevalent type and distributed in all the departments,and 10 strains(18.5%) belonged to type B which only distributed in the intensive care units(ICU) of neurology and neurosurgery departments.OXA-66 gene was carried by all the 54 strains,OXA-23 gene and its upstream insertion sequence ISAba1 was carried by 53 stains,and the armA gene of 16S rRNA methylase was carried by 41 strains.Conclusion Type A of IRAB was disseminated widely in the clinical departments of our hospital,while type B spread in ICU of neurology and neurosurgery departments.The existence of OXA-23 gene and its upstream insertion sequence ISAba1 was the main cause leading IRAB to resist carbapenems.16S rRNA methylase armA gene was widely distributed in IRAB strains.