耐氨基糖苷类抗生素鲍曼不动杆菌中armA和rmtB甲基化酶基因的检测

Identification of armA and rmtB methylase genes from aminoglycosides-resistant Acinetobacter baumannii

目的了解我院临床分离鲍曼不动杆菌对氨基糖苷类抗生素的耐药性,并检测其耐药基因。方法收集我院2009年1—10月临床分离鲍曼不动杆菌共80株,采用CLSI推荐的纸片扩散法(K-B法)对分离菌株进行抗生素敏感试验。用PCR法筛选2种甲基化酶基因armA、rmtB,并对阳性标本进行测序。结果 80株鲍曼不动杆菌对阿米卡星、庆大霉素、链霉素和奈替米星的耐药率分别为66.2%、72.5%、87.5%和68.8%,对4种氨基糖苷类抗生素全部耐药52株(65%),耐药菌株中armA基因阳性48株(60%),未检出rmtB阳性菌株。结论近年来我院鲍曼不动杆菌分离率逐年增高,16S rRNA甲基化酶基因armA在鲍曼不动杆菌广泛存在,且对多种抗生素耐药,应引起临床医师高度关注。

Objective To investigate the resistance of A. baumannii to aminoglycoside antibiotics and identify 16S rRNA methylase genes armA and rmtB.Methods A total of 80 clinical isolates of A. baumannii were collected from patients in Shanghai Renji Hospital from January to October in 2009. Antimicrobial susceptibility test was carried out for these isolates according to an agreed protocol using Kirby-Bauer （K-B） method. The 16S rRNA methylase genes armA and rmtB were amplified by PCR. The positive PCR-products were purified and sequenced. Results The resistance rate of the 80 A. baumannii isolates to amikacin,gentamicin,streptomycin,netilmicin was 66.2%,72.5%,87.5%,and 68.8% respectively. Fifty-two （65%） strains were resistant to all the four aminoglycoside antibiotics,of which 48 isolates were armA-positive （60.0%）. However,rmtB-postive isolate was not identified. Conclusions The prevalence of aminoglycosides-resistant A. baumannii is increasing in our hospital. The 16S rRNA methylase gene armA is widely present in A. baumannii isolates. Such isolates are highly resistant to multiple antibiotics,which may become a clinical concern.