Mechanisms of carbapenems resistance Pseudomonas aeruginosa isolated from burn patients

Background: The aim of this study was to investigate the molecular epidemiology and carbapenem resistance mechanisms of P. aeruginosa isolated from burn patients in Azerbaijan, Iran. Methods: Thirty-eight P. aeruginosa was isolated from burn patients. The disk diffusion and agar dilution methods were used for determination of antibiotics susceptibility patterns. AmpC and efflux pumps overproduction detected by the phenotypic methods. The presence of carbapenemase encoding genes was detected by the multiplex PCR. The expression of OprD and mexAB efflux pumps was also evaluated by the Real-Time PCR. Random Amplified Polymorphic DNA Typing (RAPD-PCR) was used for the genotyping of carbapenem-resistant P. aeruginosa (CRPA). Results: The results of MIC were exhibited high levels of resistance to all classes of antibiotics except colistin and polymyxin B. The initial screening by the carbapenem disks was indicated 24 isolates (63.15%) as CRPA. Different mechanisms of carbapenem resistance were observed including carbapenemase production (8.4%), overexpression of AmpC (25%), and decreased expression of OprD (75%). Over expressed efflux pumps were detected in 19 (79.1%) of isolates by the phenotypic assay or Real-Time PCR (over expression of MexB). The resistance to carbapenem was multifactorial in most cases (58.3%).The RAPD genotyping revealed different patterns with 9 clusters (A-I). Conclusions: According to our results the prevalence of CRPA is at an alarming level in Azerbaijan, Iran. Our results did not demonstrate an epidemic clone. The most common mechanism of carbapenems resistance was decreased expression of OprD. Therefore, we suggest reconsideration in the management program of burn patients caused by CRPA in our setting.

کلیدواژه ها:

Burn ، Carbapenems ، Epidemiology ، Pseudomonas aeruginosa