The frequency of imp and vim genes among Pseudomonas aeruginosa isolates from children’s medical center of Tehran

Abstract

Background: The first report of Pseudomonas aeruginosa (P. aeruginosa) carbapenem resistant strains, and especially the Metallo-Beta-Lactam (MBL) producers was from Japan, however, further reports were global. Objectives: The current study aimed to determine the frequency of vim and imp genes among P. aeruginosa MBL producer isolated from Children Medicinal Center during from 2011 to 2012. Materials and Methods: In the current descriptive study, 90 P. aeruginosa strains were collected from different clinical samples of children referring to Children’s Medical Center of Tehran, Iran. All the isolates were identified and confirmed by the standard tests. Their resistance against common antibiotics was determined by disk diffusion method based on Clinical and Laboratory Standards Institute (CLSI) 2010 protocol. The MBL producers were screened by Combined Disk Diffusion test (CDDT) and using imp-imp/Ethylen Ediamine Tetra Acetic Acid (EDTA), and increasing of 7 mm≤ the diameter of inhibiting zone. The frequency of vim and imp genes was determined by Polymerase Chain Reaction (PCR). Results: Based on standard tests including Triple Sugar Iron Agar and Oxidation- Fermentation (OF) media and disability of the bacteria for glucose fermentation, 90 P. aeruginosa strains were confirmed. Their resistance against the following antibiotics was evaluated by disk diffusion method: 36.6% to cefotaxim, cefpodoxim and ticarcillin 33.3%, meropenem and aztreonam 32.2%, amikacin 28.8%, ciprofloxacin and ceftriaxon 27.7%, ceftazidime 22.3% and imipenem 15.5%. By PCR the frequency of imp gene with its 328 base pair band was (3.3%). The vim gene was not detected among the tested strains. Conclusions: Despite of high resistance of P. aeruginosa, the resistance rate of P. aeruginosa strains isolated from children in the current study was not high. Then accurate prescription of antibiotics can decrease the speed of resistance creation.