整合子在鲍曼不动杆菌多重耐药机制分析

目的:调查我院鲍曼不动杆菌耐药性;了解整合子类型以及整合子携带耐药基因盒特征。方法:收集我院临床分离鲍曼不动杆菌。细菌鉴定及药敏由MicroScan Walk Away 40仪器完成,整合子分类检测及开放阅读框扩增由PCR法完成。开放阅读框扩增产物经琼脂糖凝胶电泳及凝胶回收试剂盒回收纯化后进行DNA测序分析,测序结果在Genebank上作比对。结果:62株鲍曼不动杆菌有11株呈多重耐药,阳性率17.7%,11株鲍曼不动杆菌对氨基糖苷类药物阿米卡星,妥布霉素,庆大霉素均耐药,其余菌株较敏感。11株鲍曼不动杆菌中均检出整合子;进一步分类鉴定显示均为Ⅰ类整合子,未检出Ⅱ类和Ⅲ类整合子。开放阅读框可变区扩增产物为(0.3～2.5)KB不等条带,测序结果证实11株Ⅰ类整合子含有6个不同耐药基因盒:blam-1,orfX,aacA4,catB3,dfrA1,aadA1。其中7株均出现catB3,aacA4和dfrA1组合。结论:与其他报道相比较,我院鲍曼不动杆菌多重耐药率相对较低,但耐药鲍曼不动杆菌携带整合子率较高,且均为Ⅰ类整合子;其整合子基因盒含有多种耐药基因编码,其中aacA4,catB3和dfrA1耐药基因组合在本地区占优势。

Detection of the Integron and Gene Cassettes of Acinetobacter Baumannii

Objective:To investigate the drug-resistance and the integrons’ distribution of Acinetobacter baumannii isolated from our hospital, and to understand the type of the integrons and the features of gene cassettes carried by integron.Methods:ColIected clinical isolates between January in 2008 and December in 2009;the identification and drug-sensitivity test were assayed by Micro Scan Walk Away 40;the detection,classification of integrons and the identification of open reading frame were performed by PCR.And then through agarose gel electrophoresis,PCR amplified products of open reading frame of the integrons were recollected with gel re-harvest kits.Gene cassettes of 11 integrons were sequenced.Results:Apart from imipenem,the drug-resistant rate of is 17.7.Of 11 A.baumannii clinical isolates,11 isolates carried the integrons,further identified and confirmed all of them belonged to class 1 integrons and no class 2,3 integrons were found.The PCR products length of open reading frame of 11 integrons ranged 0.3 kb to 2.5 kb.Gene sequence showed that the positive integrons detected contained 6 different gene cassettes(aacA4,dfrA1,blam-1,catB3,orfX, aadA1).The cassette arrays aacA4,catB3 and dfrAl were found in seven integrons detected.Conclusion:Resistance rates of A.baumannii clinical isolates in our region were relatively lower;But Integrons of multi-drug resistant strains in A.baumannii clinical isolates from our hospital had higher distribution frequencies and all of them belonged to class 1 integron.Integron cassettes gene in A.baumannii carried multi-drug resistant gene code. The cassette arrays aacA4,catB3 and dfrA1 predominated in our region.