耐碳青霉烯鲍曼不动杆菌的耐药机制及分子流行病学

Resistant mechanisms and molecular epidemiological characteristics of carbapenem-resistant Acinetobacter baumannii

目的碳青霉烯耐药鲍曼不动杆菌(CRAB)逐年升高的分离率和全球播散已成为极为严重的问题,本研究目的是阐明我院CRAB的耐药机制和分子流行病学特征。方法使用gyrB多重PCR方法将我院2014年7月—2015年6月分离的327株非重复醋酸钙-鲍曼不动杆菌复合体(ABC)鉴定到种,VITEK-2仪器法和E-test法测定抗菌药物的最低抑菌浓度(minimal inhibitory concentration MIC),PCR方法检测常见的碳青霉烯酶耐药基因、ISAba1并测序,Turton 2组多重PCR方法进行分子分型。结果327株ABC中有315株鲍曼不动杆菌(ABA)、9株皮特不动杆菌和3株医院不动杆菌,ABA、皮特和医院不动杆菌对亚胺培南的耐药率分别为91.7%、0和66.7%,耐药株主要分离自急诊科和呼吸ICU。ABA bla_(OXA-23-like)和ISAba1检出率均为91.1%,测序均为bla_(OXA-23),bla_(OXA-51-like)和ISAba1检出率分别为100%和0.3%,测序主要为bla_(OXA-66)和bla_(OXA-69),未检测到其他OXAs型、NDM、IMP、GIM、KPC、SIM、VIM和GES酶基因。Turton分子分型76.8%属于国际克隆Ⅱ型(IC Ⅱ)。结论携带bla_(OXA-23)和ISAba1的IC Ⅱ克隆是我院主要的流行克隆株,克隆播散是CRAB感染增加和暴发的重要原因。

Objective The increasing prevalence and global spread of earbapenem-resistant Acinetobacter baumannii （CRAB） has become a serious problem. This study was to investigate the resistant mechonism and molecular epidemiological characteristics of CRAB isolates collected from our hospital. Methods 327 non- duplicated Acinetobacter calcoaceticus-Acinetobacter baumannii complex （ABC） isolates collected between 2014.7 and 2015.6 were identified using gyrB multiplex PCR. Antimicrobial susceptibility tests were performed using the minimal inhibitory concentrations （MIC） of E-test and VITEK-2. PCR and sequencing were performed to detect the common genes encoding carbapenemase and insertion sequence of ISAbal. Isolates were typed by Turton two groups multiplex PCR. Results A total of 315 A. baumannii （ABA）, 9 A. pittti, and 3 A. nosocomialis were identified. The resistance rates ofABA, A. pittii andA. nosocomialis to impenem were 91.7%, 0, and 66.7%, respectively. Resistant isolates were collected mainly from the department of emergency and respiratory ICU. Among A. baumannii, 91.1% wore positive for blaOXA-23-like and ISAbal, which were confirmed to be blaOXA-2e; 100% and 0.3% were positive for blaOXA-51-like and ISAbal, which were confirmed to be blaOXA-66 or blaOXA-69. The isolates were negative for other OXAs, NDM, IMP, GIM, KPC, SIM, VIM, and GES carbapenemase genes. Of 315 A. baumannii isolates, 76.8% belonged to international clones Ⅱ （IC Ⅱ）. Conclusion IC Ⅱclone containing blaOXA-23 with ISAbal upstream of the gene is the predominant clone. These results suggested that the clone spread played an important role in the outbreak of CRABs in our hospital.