亚胺培南耐药铜绿假单胞菌的金属β-内酰胺酶检测

Detection of metallo-β-lactamase in imipenem-resistant Pseudomonas aeruginosa

目的了解金属β-内酰胺酶在广州地区铜绿假单胞菌中的流行状况及其流行亚型,完善广州地区金属β-内酰胺酶的分子流行病学资料。方法采用双纸片协同法和双纸片增效法对164株亚胺培南耐药的铜绿假单胞菌筛选金属β-内酰胺酶表型阳性的菌株,采用PCR检测5类金属β-内酰胺酶的编码基因(IMP家族、VIM家族、GIM-1、SPM-1和SIM-1),利用生物信息学的方法对检测到的金属β-内酰胺酶亚型进行比对分析并制作分子进化树。结果 164株亚胺培南耐药的铜绿假单胞菌中筛选出22株金属β-内酰胺酶表型阳性的菌株,IMP阳性15株(9.1%),其中11株为IMP-9亚型,另外4株携带一个新的亚型,命名为IMP-25,VIM阳性5株(3.0%),均为VIM-2亚型,未检测到GIM-1、SPM-1和SIM-1型金属β-内酰胺酶。结论广州地区铜绿假单胞菌产金属β-内酰胺酶的基因型已经出现多型化的特征,同时存在IMP型和VIM型金属β-内酰胺酶的流行,本次研究发现了一个新的金属β-内酰胺酶亚型(IMP-25),为IMP家族金属β-内酰胺酶的多样性及其分子流行病学资料提供了新的信息。

Objective To identify the genetypes of metallo-β-lactamases （MBLs） in Pseudomonas aeruginosa isolated in Guangzhou, and consummate the MBL molecular epidemiology data of Guangzhou. Methods The combined disk method and double-disk potentiation screen test method were used to detect MBLs in 164 imipenem- resistant P. aeruginosa strains, and MBL genetypes including IMP-type, VIM-type, GIM-1, SPM-1, and SIM-1, were determined by PCR amplieation. The genetypes of MBLs were analyzed and phylogentic tree was made up by bioinformatics analyzing tools. Results Of the 164 imipenem-resistant P. aeruginosa, 22 exhibited the inhibitory zones between caftazidime or imipenem disks and inhibitor-added disks respectively, suggesting production of MBLs. 15 isolates were positive with the primers specific for bla IMP , and 5 isolates were positive with primers specific for bla VIM, while bla SPM, bla GIM and blastM were not detected in any of the 22 isolates. The sequence analysis revealed that 11 isolates carried bla IMP-9 and that 5 isolates harbored bla VIM-2. The other 4 isolates were found to carry a variant of bal IMP-9, named bla IMP-25. Conclusion The gene type of MBL produced by P. aeruginosa in Guangzhou is multiple,existing IMP-type MBL and VIM-type MBL simultaneously. Besides, we reported a new subtype of IMP, named IMP-25, and it added the MBL molecular epidemiology data of MBL.