OXA-23型酶介导的鲍曼不动杆菌对碳青霉烯类抗生素耐药分子传播机制

目的：探讨OXA-23酶在介导鲍曼不动杆菌碳青霉烯类抗生素耐药过程中的传播机制。方法对2010年9月至2012年3月58株产OXA-23型碳青霉烯酶鲍曼不动杆菌进行深入研究，所有菌株运用PCR mapping方法对blaOXA-23基因的周围结构进行扩增及测序分析；根据PFGE型别挑选不同克隆的菌株，进一步采用S1-PFGE以及ApaI-PFGE联合Southern blot杂交法对blaOXA-23基因进行定位分析。结果58株菌中有47株菌的blaOXA-23基因周围结构为Tn2009转座结构、11株为Tn2008转座结构；58株菌属于8个不同的克隆型别（A、B、C、D、E、F1、F2、G和H克隆），其中E克隆的blaOXA-23基因存在2个拷贝，分别位于质粒及染色体上，质粒大小为78.2kb左右；其余克隆菌blaOXA-23基因定位于染色体上，所在片段大小为310.1kb左右，其中D克隆存在2个染色体拷贝。结论转座结构是导致blaOXA-23基因迅速在鲍曼不动杆菌中转移的重要元件，导致鲍曼不动杆菌碳青霉烯类抗生素耐药传播和扩散。

Objective To illustrate the molecular transmission mechanism of carbapenem-resistance mediated by OXA-23 type carbapenemase in A. baumannⅡ. Methods Fifty-eight strains collected from September 2010 to March 2012 were involved in our study. PCR mapping method followed by sequencing was used to analysis the surrounding structure of the blaOXA-23 gene. Those isolates originating from different clones according to PFGE analysis were picked out to detect the gene location of the blaOXA-23 with S1-PFGE and ApaI-PFGE followed by Southern blotting method. Results 47 in 58 strains harbored the blaOXA-23 gene in Tn2009 transposon structure,while 11 in Tn2008. Only one type of PFGE clone strain （Clone E） harbors the blaOXA-23 gene both in plasmid （ranging around 78.2kb） and in chromosome. The blaOXA-23 gene was located in chromosome in the rest types of clones, in which two copies of clones were found in Clone D. Conclusion Both transposon was the main factors mediated the blaOXA-23 gene transmission among A. baumannⅡ,which was also the molecular basis leading to the epidemic of carbapenem-resistant A. baumannⅡ.