Abstract

Background: Pseudomonas aeruginosa is a Gram-negative bacterium that plays a major role in development of opportunistic and severe infections in burn patients. Occurrence of enzymes capable of inactivating all beta-lactams including carbapenems is new problem in treatment of patients. The objective of this study was to investigate the prevalence of Metallo-Beta-Lactamases (MBL) enzymes blaVIM, blaIPM and blaNDM in Pseudomonas aeruginosa strains isolated from burn wounds in Yazd city, Iran. Methods: In this cross-sectional study, 180 burn wound-specimens were collected from burn-hospital belonged to Shahid Sadoughi University of Medical Sciences in Yazd during one year and were cultured at microbiology laboratory of School of Medicine of this university. Suspected colonies were identified by conventional biochemical methods such as utilization of sugars, motility, and oxidase production. Sugar utilization in the Oxidation-Fermentation medium (OF), growth at 42°C and pigment production tests were performed for oxidase positive and non-fermentative colonies on Triple Sugar Iron (TSI) test. Antibiotic susceptibility was determined by Kirby-Bauer methods according to the Clinical and Laboratory Standards Institute (CLSI) standards. Etest metallo-beta-lactamase (Etest MBL) method was used for phenotypic detection of MBL and blaVIM, blaIPM and blaNDM were determined by polymerase chain reaction (PCR) method using specific primers. Findings: Out of 180 burn wound specimens, 54 (30) was identified as Pseudomonas aeroginosa. Out of 54 isolates, 70, 66 and 74 were resistance to ertapenem, meropenem and imipenem respectively; 64 and 74 of isolates were resistant to meropenem and imipenem respectively. MBL enzymes were detected in 29.5 of isolates. Nine isolates (16.6) and 5 isolates (9.2) had blaVIM and blaIPM respectively and 2(3.7) isolates had blaVIM, blaIPM and blaNDM simultaneously. None of the isolates had blaNDM. Conclusion: The results of this study show that the prevalence of MBL enzymes and antibiotic resistance in burn patients is high and it is necessary to determine susceptibility testing before treatment.