Determining the distribution of the blaVIM gene in imipenem-resistant Pseudomonas aeruginosa strains isolated from three different hospitals

BACKGROUND: In recent years, increase in the prevalence of the metallo-beta-lactamase (MBL) production among carbapenem-resistant Pseudomonas aeruginosa strains has been observed. The aim of this study was to determine the incidence and distribution of MBL production in carbapenem-resistant P. aeruginosa strains at different hospitals and to compare with the phenotypic and genotypic methods in MBL production. METHODS: Forty-four out of 90 P. aeruginosa strains isolated from different wards and clinical specimens from three different hospitals were resistant to imipenem, and MBL was investigated with phenotypic and genotypic methods. RESULTS: MBL was detected in 54.5% of 44 P. aeruginosa strains using the combined disc test. Specific DNA primers were used to investigate the presence of genes coding for VIM-type enzymes. In 47.7% of the imipenem resistant strains the presence of the bla(VIM) gene was detected using PCR method. One hundred percent of MBL-producing strains were resistant to trimethoprim/sulfamethoxazole, tetracycline, and aztreonam, whereas ceftazidime was the most effective antibiotic to fight against MBL-producing strains (the lowest resistance was observed). P. aeruginosa strains carrying bla(VIM) gene were from the urine samples collected from the general intensive care unit of the second hospital, which have the highest frequency of antibiotic resistance, were observed to be the main source in the distribution of MBL. CONCLUSION: Consequently, it was pointed out that the dissemination of the bla(VIM) gene was found high percentage in P. aeruginosa strains isolated from different hospitals and the phenotypic methods were confirmed considerably by genoypic methods.