耐碳青霉烯类鲍曼不动杆菌OXA基因检测及同源性分析

Study on oxacillinase encoding gene and homology of carbapenem-resistant Acinetobacter baumannii

目的了解台州地区碳青霉烯类耐药鲍曼不动杆菌的耐药性、碳青霉烯酶基因型以及同源性。方法 63株碳青霉烯类耐药鲍曼不动杆菌经VITEK 2 Compact进行细菌鉴定及药敏分析,用K-B法复核药敏结果,采用多重PCR扩增分析碳青霉烯酶的基因型;采用脉冲场凝胶电泳(pulsed field gel electrophoresis,PFGE)分析其同源性。结果 63株菌株为多重耐药菌株,除多粘菌素、阿米卡星、头孢哌酮/舒巴坦外,对其他常用抗生素的耐药率均在70%以上。63株菌株检测出OXA-51基因60株(95.2%),OXA-23基因58株(92.1%),两个基因同时存在的有58株(92.1%)。PFGE结果显示碳青霉烯类鲍曼不动杆菌主要分为5个克隆型,其中A、B两个为主型。结论产OXA酶是台州地区耐碳青霉烯类鲍曼不动杆菌的主要耐药机制之一,其中OXA-23是主要的基因型。

Objective To analyze the drug resistance and genotypes of carbapenem-resistant Acinetobacter baumannii and their ho- mology in Taizhou. Methods 63 Acinetobacter baumannii strains were identified and their drug susceptibility were detected by using VITEK 2 Compact. The results of drug susceptibihty test were rechecked by Kribry-Bauer methods. The genes of carbapenemase were am- plified by multiplex polymerase chain reaction. Homology of the resistant isolates was analyzed by PFGE. Results The 63 strains were multi-resistant. The resistant rates to common antimicrobial agents exceeded 70% except to polymyxin, amikacin, and cefoperazone/sul- bactam. Among the 63 strains, 60 isolates （95.2%） carried OXA-51 gene, 58 isolates （92.1%） carried OXA-23 gene, and 58 strains （92.1% ） possessed both the two genes. PFGE showed that Acinetobacter baumannii can be divided into 5 different genotypes, with type A and type B playing a dominant role in epidemiology. Conclusion The production of OXA carbapenemase in Acinetobacter baumannii was one of the main mechanisms of carbapenem-resistance in our hospital. OXA-23 is the major carbapenemase gene.