鲍曼不动杆菌临床分离株耐药性与OXA-碳青霉烯酶基因型研究

Association of Genotype of OXA-carbapenemases of Acinetobacter Baumannii and Antibiotic Resistance

目的研究我院鲍曼不动杆菌耐药性与OXA-碳青霉烯酶基因之间的关系。方法2005年1月至2006年6月我院临床分离出的共120株鲍曼不动杆菌采用琼脂对倍稀释法进行常用抗菌药物的敏感性研究;根据耐药表型对耐亚胺培南/西司他丁(IMP)菌株进行碳青霉烯酶基因blaOXA-23、blaOXA-24的PCR检测及基因序列分析。结果120株临床分离鲍曼不动杆菌对11种抗菌药物的耐药率均超过50%,对IMP的耐药率低于50%(44.4%)。多重耐药常见,对3种以上抗菌药物耐药者达91.67%。对IMP耐药的50株鲍曼不动杆菌中,PCR检测13株阳性,序列分析证实均为blaOXA-23;未发现blaOXA-24。结论我院鲍曼不动杆菌多重耐药常见,blaOXA-23是主要的OXA-碳青霉烯酶基因型,可能是医院感染的主要基因型。

Objective To determine the association of the antibiotic resistance of clinical isolates of Acinetobacter baumannii and the genotype of OXA-carbapenemases. Methods One hundred and twenty Acinetobacter baumannii strains were isolated from clinical specimens in the West China Hospital from January 2005 to June 2006. The MICs of 12 common antimicrobial agents were determined by 2-fold agar dilution method followed by NCCLS recommendations. The blaOXA-23 and blaOXA-24 of those with resistance to IMP were amplified by PCR. Results The resistant rates of the 120 isolates to 11 common antimicrobial agents exceeded 50% except for IMP （44.4%）. One hundred and ten strains were resistant to more than three common antimierobial agents, with a resistant rate of 91.67%. Of the 50 strains resistant to IMP, 13 stains carried blaOXA-23. No blaOXA-24 was found in the resistant isolates. Conclusion Multiple antibiotic resistances are common in Acinetobacters baumannii isolated in the West China Hospital. OXA-23-type carbapenemase is the major earbapenemase that contributes to the nosocomial infection of Acinetobacters baurnannii.