重症监护病房产VIM-2型金属酶绿脓假单胞菌的研究

Study on the VIM-2 metallo-beta-lactamase-producing Pseudomonas aeruginosa strains in intensive care unit

目的 分析重症监护病房产金属 β内酰胺酶绿脓假单胞菌的同源性、金属酶基因型及转移机制。方法 用 2 巯基丙酸协同试验筛选重症监护病房分离的对亚胺培南耐药的绿脓假单胞菌中的产金属酶株 ,聚合酶链反应 (PCR)、克隆测序确定耐药基因 ,整合子PCR扩增 ,脉冲场凝胶电脉分析同源性。结果 2 6株绿脓假单胞菌 2 巯基丙酸协同试验阳性 ,酶粗提液能水解亚胺培南 ,活性能被EDTA抑制。VIM型金属酶引物PCR扩增阳性 ,经克隆测序证实为VIM 2型金属酶。整合子可变区序列分析表明 ,blaVIM 2位于Ⅰ类整合子上 ,该基因上游含有 1个aacA4基因 ,下游为aadB基因。脉冲场凝胶电脉结果证实产酶株均来自同一克隆。结论 医院重症监护病房有产VIM 2型金属酶绿脓假单胞菌的流行 。

Objective To analyze the homology and resistance gene type of metallo-beta-lactamase-producing Pseudomonas aeruginosa strains from ICU.Methods Using 2-mercaptopropanoic acid-disc synergy test to screen metallo-beta-lactamase positive strains from imipenem-resistant Pseudomonas aeruginosa isolates in ICU, PCR and sequence analysis were used to identify the resistance gene, the variable region of integron was amplified by PCR, the homology of these strains were analyzed by pulsed-field gel electrophoresis (PFGE). Results 26 strains of Pseudomonas aeruginosa were suggested to produce metallo-beta-lactamase by 2-mercaptopropanoic acid synergy test. Using primers described for bla(VIM), the amplification was observed among all 26 strains and a VIM-2 metallo- enzyme was identified. Sequencing of the PCR amplicon of the variable region of integron, containing the gene cassette bla(VIM-2), revealed the structure of the class Ⅰ integron. Upstream of the bla(VIM-2) gene resided an aacA4 gene, and an aadB gene was following the bla(VIM-2). 26 strains had the same clonal origin based on PFGE pattern.Conclusion VIM-2 metallo-beta-lactamase-producing Pseudomonas aeruginosa strains were prevalent in ICU and the resistant gene was located in the class Ⅰintegron.