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

Abstract

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.