耐碳青霉烯类铜绿假单胞菌金属β-内酰胺酶和基因捕获元件基因检测及同源性分析

Detection and homological analysis of metallo-β-lactamase genes,intI gene and ISCR1 in carbapenem-resistant Pseudomonas aeruginosa

目的了解大连地区分离的耐碳青霉烯类铜绿假单胞菌的金属β-内酰胺酶、整合子I和ISCR1的分布情况,并分析其基因多态性特征。方法收集临床分离的89株耐亚胺培南铜绿假单胞菌,PCR检测金属酶、整合子I、ISCR1耐药基因。脉冲场凝胶电泳(PFGE)进行细菌基因分型。结果 89株亚胺培南耐药的铜绿假单胞菌中,ISCR1基因阳性菌25株(25/89,28%),其中84%(21/25)为多重耐药,5类及以上药物耐药的菌株占64%(16/25),金属酶基因阳性为11株(11/89,12%),其中有8株携带IMP-1基因,3株携带VIM-2,整合子I基因阳性43株(43/89,48%)。但携带金属酶的菌株整合子I、ISCR1基因扩增均为阴性;PFGE分型结果显示:89株耐亚胺培南的铜绿假单胞菌分为15个基因型(A^O),其中A型46株、B型16株、C型4株、D型5株、E型4株、F型3株、G型2株、H型2株,I型~O型各有1株。基因型集中的A型~G型,各型中的菌株来源于不同医院,呈多态性,每群均存在克隆株。结论基因捕获元件整合子I基因及ISCR1广泛分布在大连地区耐碳青霉烯类铜绿假单胞菌中,并与细菌的多重耐药、泛耐药显著相关,特别是ISCR1基因;大连地区整合子I、ISCR1并未携带金属酶基因盒。PFGE结果提示本地区铜绿假单胞菌具有基因多态性,但仍存在高度同源性的流行优势基因型。

Objective To investigate the distribution of etallo-beta-lactamase, integron I and ISCR1, and analyze the characteristics of gene polymorphism in carbapenem resistant Pseudomonas aeruginosa in Dalian. Methods 89 strains of clinical isolates of imipenem resistant Pseudomonas aeruginosa were collected. PCR was used to detect the resistant genes of metallo enzyme, integron I and ISCR1. Bacterial genotypes were detected by using Pulsed field gel electrophoresis （PFGE）. Results Of the 89 strains of imipenem resistant Pseudomonas aeruginosa, 25 strains carried ISCR1 gene （25/89, 28%）, 21 isolates （21/25, 84%） of which were multi-drug-resistant while 16 isolates were resistant to 5 or more kinds of drugs. 11 strains carriedetallo-beta-lactamase gene （11/89, 12%）, 8 strains of which carried IMP-1 gene and 3 strains carried VIM-2 gene. 43 strains were integron I positive （43/89, 48%）. Strains carrying etallo-beta-lactamase gene were integron I negative and ISCR1 negative. PFGE showed 15 distinct PFGE genotypes （A - O）, including 46 strains of type A, 16 strains of type B, 4 strains of type C, 5 strains of type D, 4 strains of type E, 3 strains of type F, 2 strains of type G, 2 strains of type H, and 1 strain each from type I to type O. Genotypes A to G were isolated from different hospitals and presented polymorphism; there were clones of each genotype. Conclusion The integron I and ISCR1 genes widely distributed among Pseudomonas aeruginosa in Dalian, which significantly correlated with bacterial multidrug resistance and extensively drug-resistance, especially the ISCR1 gene. The strains carrying integron I and ISCR1 did not carryetallo-beta-lactamase gene cassettes. Pseudomonas aeruginosa in Dalian present genetic polymorphism, but there was dominant genotype.