耐碳青霉烯鲍曼不动杆菌插入序列及其水平传播

ISAba1 and horizontal transmission of carbapenem resistant Acinetobacter baumannii

目的了解我院耐碳青霉烯类鲍曼不动杆菌的临床分布并探讨插入序列与其耐药的关系,分析水平传播能力,为指导医院感染及临床合理应用抗菌药物提供科学依据。方法收集2013年9月-2015年6月我院临床分离鲍曼不动杆菌,经VITEK-II全自动细菌分析系统鉴定细菌并检测16SrRNA,Walkway-40/药敏测试系统进行药敏检测;多重PCR检测鲍曼不动杆菌携带β-内酰胺酶(A、B、C、D类)相关耐药基因。检测上游插入序列ISAba1与OXA-23、OXA-51、ADC连锁表达,并分析ISAbal与耐药基因OXA-23、ADC的相关性。质粒接合试验验证OXA碳青霉烯酶基因的水平转移。结果耐碳青霉烯类的鲍曼不动杆菌(CRAB)与碳青霉烯类敏感的鲍曼不动杆菌(CSAB)抗生素耐药率差异有统计学意义(Ps<0.01)。CRAB与CSAB产酶基因(OXA-23、ADC、TEM)检出率差异明显。50株CRAB中40株检测出ISAbal-OXA-23连锁基因,1株检测出ISAbal-OXA-51连锁基因。接合试验阳性株检测出OXA-23、OXA-24、OXA-51及插入序列。结论我院CRAB主要是产OXA-23、OXA-24、OXA-51、ADC、TEM型碳青霉烯酶,ISAbal常出现在OXA-23基因上游,ISAbal-OXA-23可能是CRAB重要的耐药机制。

Objective To explore the relation between the insertion sequence ISAba1 and drug resistance of carbapenem resistant Acinetobacter baumannii isolated from our hospital,analyze its capability of horizontal transmission,and provide scientific evidence for rational use of antibiotics.Methods Clinical specimens were collected from our hospital from September 2013 to June 2015.The VITEK-II and Walkway-40 automated microbial identification/susceptibility testing systems were used to identify the bacteria and test drug resistance.Multiplex PCR detection method was used to identify the resistantβ-lactamase genes of A.baumannii.The upstream insertion sequence ISAba1 and the expression of OXA-23,OXA-51 and ADC were detected,and the correlation between ISAba1 and the expression of resistant genes OXA-23 and ADC was analyzed.The horizontal transfer of carbapenemase gene OXA was verified with plasmid conjugation test.Results The antibiotic resistance rates of carbapenem-resistant Acinetobacter baumannii（CRAB）and carbapenem sensitive Acinetobacter baumannii（CSAB）were significantly different（Ps0.01）.Compared with CSAB,the detection rates of OXA-23,ADC and TEM genes in CRAB were significantly different.In the 50 strains of CRAB,40 strains were detected as carrying ISAbal-OXA-23 linkage gene and 1 strain carrying ISAba1-OXA-51 linkage gene.OXA-23,OXA-24,OXA-51 and insertion sequences were detected in the conjugation positive strains.Conclusion The mechanism of resistance of carbapenem resistant A.baumannii is the production of OXA-23,OXA-24,OXA-51,ADC and TEM type carbapenemase.ISAbal often exists in the upstream of OXA-23 gene,and ISAbal-OXA-23 may be related to the drug resistance of CRAB.