鲍曼不动杆菌armA基因的分布与耐药性的研究

The prevalence of 16S rRNA methylase gene armA and drug resistance in Acinetobacter baumannii

目的调查我院鲍曼不动杆菌中16S rRNA甲基化基因armA的分布以及与鲍曼不动杆菌耐药谱的关系，并初步探讨其在分子流行病学分析中的作用。方法收集72株鲍曼不动杆菌，采用K-B法对鲍曼不动杆菌进行药物敏感试验，后采用PCR筛选鲍曼不动杆菌的16S rRNA甲基化基因。armA，并利用随机扩增多态性DNA法（RAPD）技术进行基因分型。统计各鲍曼不动杆菌菌株对多种氨基糖苷类药物的药敏结果，并分析基因型与耐药性的关系。结果根据PCR产物片段大小，72株鲍曼不动杆菌共有armA基因阳性菌株20株（27．8％）。含有armA基因型鲍曼不动杆菌菌株对庆大霉素、妥布霉素和阿米卡星的耐药率均为90％；随机扩增多态性DNA法显示20株armA基因阳性的鲍曼不动杆菌主要分为7型，A型为优势克隆株。结论产16S rRNA甲基化基因armA的鲍曼不动杆菌菌株可对多种氨基糖苷类抗生素高水平耐药。同一克隆菌株在病房内和病房间的传播为我院armA以基因传播的主要方式。

Objective To investigate the prevalence of 16S rRNA methylase gene armA and to analyze their effect on the drug resistance in multi drug-resistant strains ofAcinetobacter baumannii. Methods A total of 72 Acinetobacter baumannii isolates were collected from the Second Xiangya Hospital from Jan. 2008 to Dec. 2008. The size of inhibitory zone of these strains to gentamycin, tobramycin and amikacin were determinate using Kirby-Bauer（K-B） method. The 16S rRNA methylase genes armA were detected by PCR. PCR products were purified and sequenced. Then we used randomly amplified polymorphic DNA method （RAPD） genotyping technology for the establishment of DNA fingerprinting. In addition, we compared drug sensitivity test with RAPD technology. Results Twenty isolates of 72 strains were armA positive and the resistance rates of the strains with armA gene to gentamycin, tobramycin, amikacin were 90.0%, 90.0% and 90.0%, respectivily, armA positive stains were divided into 7 types using RAPD technology. A genotype was the advantage type. Conclusion The study showed that 16S rRNA methylases gene arrrtA was prevalent in Acinetobacter baumannii which could lead to resistant to almost all aminoglycosides at a high level. And the main form of armA gene prevalence in our hospital was the spread of the same clone strain inside and outside of clinic department.