Objective To analyze the carbapenemase genotypes and homogeneity among the isolates of Acinetobacter baumannii, and identify the factors contributing to the increasing carbapenem resistance. Methods WHONET 5. 0 software was used to analyze the changing prevalence of antibiotic resistance. Thirty-five carbapenem-resistant A. Baumannii isolates were collected from an Intensive Care Unit between 2008 and 2009, All strains were identified by VITEK-2 and tested by Kirby-Bauer disk diffusion test. The carbapenemases and their relationship with ISAba1, metallo-β-lactamases genes were analyzed by PCR. Genotyping were conducted by pulsed-field gel electrophoresis. Results The prevalence of meropenem-resistant strains increased rapidly from 10. 8% to 62. 3%, and imipenem-resistant strains increased from 13. 5% to 58. 8%. Eight clones were identified in the 35 A. Baumannii strains. The blaOXA-S1,blaOXA-23,and blaOXA-58 genes were identified in 94. 29% (33/35) , 57.14% (20/ 35) and 17. 14% (6/35) of these A. Baumannii strains, respectively. ISAba1-associated blaoxA-23 genes were prevalent in carbapenem-resistant A. Baumannii. No metallo-β-lactamases gene was identified. Conclusions OXA-type carbapenemases (mainly OXA-23) play an important role in carbapenem-resistant A. Baumannii. Attention should be paid to the cross-infection and prevalence of carbapenem-resistant A. Baumannii in ICU.%目的 分析耐碳青霉烯类抗生素鲍曼不动杆菌基因型,进行同源性分析,探讨碳青霉烯类抗生素耐药率升高的原因.方法 应用WHONET 5.0分析广州医学院第一附属医院重症监护病房(ICU)分离的鲍曼不动杆菌耐药率变化.收集2008年1月至2009年12月ICU碳青霉烯类抗生素耐药鲍曼不动杆菌35株,应用VITEK-2全自动细菌鉴定仪进行菌株鉴定,采用K-B纸片扩散法测定15种抗菌药物的敏感性,PCR检测金属β内酰胺酶及碳青霉烯酶OXA基因,脉冲场凝胶电泳(PFGE)分析同源性.结果 该院分离的鲍曼不动杆菌对碳青霉烯类抗生素的耐药率显著增加,对美罗培南的耐药率从10.8％升高到62.3％,对亚胺培南的耐药率从13.5％升高到58.8％.PFGE分析存在8个克隆；blaoxA-51、blaoxA-23、blaoxA-58阳性的分别为33株(94.3％)、20株(57.1％)和6株(17.1％).ISAba1相关blaoxA-23是碳青霉烯酶主要的存在形式.未检测到金属β内酰胺酶.结论 该院ICU分离的鲍曼不动杆菌OXA-23型碳青霉烯酶基因检出率最高,并存在交叉感染的情况,应引起临床重视.
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