Detection of blaIMP and blaVIM Metallo-Beta-Lactamases Genes in Pseudomonas aeruginosa Strains Isolated from Wound of Burnt Patients in Tehran Shahid Motahari Hospital during 2011, Iran

During recent years, metallo-beta-lactamase (MBLs) producing Pseudomonas aeruginosa has been reported as an important cause of nosocomial infection. Also, infection with this bacterium has increased rate of mortality and health care costs. The aim of this study was to determine the antibiotic resistance pattern and to detect blaVIM and blaIMP Metallo-beta-lactamase genes in P. aeruginosa isolated from patients hospitalized in the burn ward. This descriptive study was conducted on P. aeruginosa strains isolated from patients hospitalized in the burn ward of Tehran Shahid Motahari Hospital between September and January 2011. For all MBL-producing strains, antibiotic resistance pattern was determined by disc diffusion method according to CLSI guidelines. CDDT method was used for detection of MBL (imipenem-imipenem+EDTA), and PCR and sequencing techniques were used to detect MBL genes, blaVIM and blaIMP. Eighty-three percent of 100 P. aeruginosa isolates were resistant to imipenem. Using combination disk diffusion test (CDDT) method, 48 isolates were detected to have MBL, of which 6 isolates were positive for blaIMP-1 gene, and all of them did not have blaVIM gene. Also, 4 (8.3%) patients with MBL-producing P. aeruginosa infection died in the hospital. The results of this study revealed that high percentage of P. aeruginosa strains are MBL-producer. Therefore, detection of MBL-producing strains is essential for better control and treatment of burnt patients.