Evaluation of Metallo-β-Lactamase-Production and Carriage of bla-(VIM) Genes in Pseudomonas aeruginosa Isolated from Burn Wound Infections in Isfahan

BACKGROUND: Metallo-β-lactamase-production among Gram-negative bacteria, including Pseudomonas aeruginosa, has become a challenge for treatment of infections due to these resistant bacteria. OBJECTIVES: The aim of the current study was to evaluate the metallo-β-lactamase-production and carriage of bla-(VIM) genes among carbapenem-resistant P. aeruginosa isolated from burn wound infections. PATIENTS AND METHODS: A cross-sectional study was conducted from September 2014 to July 2015. One hundred and fifty P. aeruginosa isolates were recovered from 600 patients with burn wound infections treated at Imam-Musa-Kazem Hospital in Isfahan city, Iran. Carbapenem-resistant P. aeruginosa isolates were screened by disk diffusion using CLSI guidelines. Metallo-β-lactamase-producing P. aeruginosa isolates were identified using an imipenem-EDTA double disk synergy test (EDTA-IMP DDST). For detection of MBL genes including bla-(VIM-1) and bla-(VIM-2), polymerase chain reaction (PCR) methods and sequencing were used. RESULTS: Among the 150 P. aeruginosa isolates, 144 (96%) were resistant to imipenem by the disk diffusion method, all of which were identified as metallo-β-lactamase-producing P. aeruginosa isolates by EDTA-IMP DDST. Twenty-seven (18%) and 8 (5.5%) MBL-producing P. aeruginosa isolates harbored bla-(VIM-1) and bla-(VIM-2) genes, respectively. CONCLUSIONS: Our findings showed a high occurrence of metallo-β-lactamase production among P. aeruginosa isolates in burn patient infections in our region. Also, there are P. aeruginosa isolates carrying the bla-(VIM-1) and bla-(VIM-2) genes in Isfahan province.