鲍曼不动杆菌的同源性及碳青霉烯酶基因分析

Homology and carbapenemase gene in Acinetobacter baumannii

目的:研究临床分离鲍曼不动杆菌的耐药性演变、同源性、产碳青霉烯酶类型及碳青霉烯酶基因型。方法:收集临床分离的72株鲍曼不动杆菌,采用VITEK-II药敏分析系统对72株鲍曼不动杆菌进行18种抗菌药物的敏感性检测。采用肠杆菌科基因间一致重复序列聚合酶链技术(ERIC-PCR)进行基因分型和同源性比对。用改良Hodge试验检测杆菌的产碳青霉烯酶表型,对碳青霉烯酶基因blaOXA-23,blaOXA-40和blaOXA-58进行PCR扩增及序列分析。结果:72株鲍曼不动杆菌对头孢哌酮/舒巴坦的耐药率最低,为8.33%,其次是阿米卡星,对其余抗菌药物的耐药率均高达70%以上。ERIC-PCR技术将其分为7个基因型,同源性分析显示其中4个基因型在医院内流行。产碳青霉烯酶的菌株有56株,blaOXA-23扩增阳性的有61株,blaOXA-58扩增阳性的有1株。结论:鲍曼不动杆菌耐药严重,且存在院内感染传播的现象;产碳青霉烯酶的菌株较多,主要的碳青霉烯酶基因型为blaOXA-23;湖南省存在blaOXA-58阳性鲍曼不动杆菌株。

Objective. To study the antibiotic resistance evolution, homolog~ phenotypes and genotypes of carbapenemase in Acinetobacter baumannii from clinical isolates. Methods： A total of 72 strains ofAcinetobacter baumannii were isolated from Xiangya Hospital of Central South University from March to May 2012. Antimicrobial susceptibility test was carried out by automatic microorganism clinical analytical system VITEK-II. 2-he homology of the 72 strains was analyzed by enterobacterial repetitive intergenic consensus-PCR （ERIC-PCR）. Modified Hodge test was used to screen carbapenemases of the strains. Carbapenemase genes blaOXA-23, blaOXA-40 and blaOXA-58 were also amplified and sequenced. Results： q-he 72 strains ofAcinetobacter baumannii remained sensitive to cefoperazone/sulbactam （resistance rate 8.33%）, followed by Amikacin. Otherwise, they were resistant to most of the antimicrobial agents （resistance rate more than 70%）. qhe 72 strains were identified as 7 epidemic clones, A-G, by means of ERIC-PCR and the phylogenetic relationship among D, E, F and G was very close, suggesting a nosocomial infection possibility. Totally 56 strains produced carbapenemase; 61 strains were positive for carbapenemase gene blaOXA-23 and 1 strain positive for blaOXA-58. All strains were negative for carbapenemase gene blaOXA-40. Conclusion： Acinetobacter baumannii strains isolated clinically are resistant to most of the antimicrobial agents and nosocomial infection had been observed. Most of the strains produce carbapenemase, among which, blaOXA-23 gene is the main carbapenemase gene. blaOXA-58 gene exists in the Acinetobacter baumannii isolates from Hunan Province.