铜绿假单胞菌中I类整合子及携带的耐药基因研究

Identification of class 1 integron carrying a novel MBL gene bla_(IMP-25) in Pseudomonas aeruginosa

目的了解整合子在广州地区铜绿假单胞菌中的分布状况及其主要类型,研究I类整合子的结构特征并探讨其与细菌多重耐药之间的相关性。方法采用PCR检测3类整合子整合酶的编码基因,并扩增整合子的可变区,运用DNA测序技术分析整合子可变区的耐药基因及其排列顺序,利用生物信息学的方法对检测到的可变区基因序列进行比对分析。结果在20株产金属-内酰胺酶铜绿假单胞菌中,15株检测到I类整合子,未检测到II类和III类整合子,其中一株铜绿假单胞菌整合子全长序列含有I类整合子整合酶、AacA4氨基糖甙乙酰转移酶、IMP-25金属-内酰胺酶、OXA-30-内酰胺酶和CatB3氯霉素乙酰转移酶的编码基因及其相应的基因重组位点,GenBank登录号为EU588392,其中IMP-25为一个新的金属-内酰胺酶亚型。结论广州地区铜绿假单胞菌中存在的整合子类型是I类整合子,并且该整合子可变区携带多种耐药基因盒,其中一个是金属-内酰胺酶新亚型IMP-25,在分子水平上阐述了I类整合子参与铜绿假单胞菌对抗生素的耐药性和多重耐药性。

Objective To investigate the distribution, main type, and characterization of integron in Pseudomonas aeruginosa isolated in Guangzhou and to analyze the correlation between integron and multidrugresistance in P aeruginosa. Methods PCR and DNA sequencing methods were used to clarify the type and context of variable region of integrons. The gene cassettes of integron and its marshaling sequence were determined by bioinformatics analyzing tools. Results Of 22 MBL-producing P. aeruginosa isolates, 15 strains were found containing class 1 integron, while no class 2 and class 3 integron was detected in any of these isolates. A length of 485 lbp variable region was found in one of the class 1 integron positive isolates by PCR amplification. The DNA sequence revealed that it comprised of a new array of aacA4-blaIMP-25-blaoxA.30-blacatB3, and the genbank number was EU588392. In addition, IMP-25 was a novel variant of IMP-type MBL. Conclution Only the class 1 integron was detected in P aeruginosa isolated in Guangzhou. It carried a novel gene cassette blaIMP-25, and mediated the resistance and multidrug-resistance ofP. aeruginosa at molecular level.