Investigation of the prevalence of genes conferring resistance to carbapenems in Pseudomonas aeruginosa isolates from burn patients

Azar Dokht Khosravi,1,2 Shahab Taee,3 Aram Asarehzadegan Dezfuli,1 Hossein Meghdadi,2 Fatemeh Shafie21Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 2Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 3Department of Biology, Faculty of Basic Sciences, Yasouj Branch, Islamic Azad University, Yasouj, IranBackground and aim: Currently, the rate of hospital-acquired infections due to drug-resistant Pseudomonas aeruginosa strains shows an increasing trend and remains one of the principal reasons for mortalilty in burn patients. This study aimed to investigate the prevalence of genes conferring resistance to carbapenems in P. aeruginosa isolates from burn patients.Methods: A total of 50 P. aeruginosa isolates were tested for antibiotic susceptibility and presence of multidrug-resistant (MDR) and extensively drug resistant (XDR) isolates, using phenotypic tests. Screening for genes conferring resistance to carbapenems was investigated by multiplex PCR method.Results: Susceptibility testing demonstrated the highest resistance against amikacin, ceftazidime (n=44/88% each), and gentamicin (84%), while colistin sulfate was the most effective antibiotic. The rate of MDR and XDR isolates was revealed as 50% and 40% respectively. We detected the following carbapenemase genes: blaNDM (32%), followed by blaOXA-48 (18%), and blaBIC-1 (14%). This study revealed a high antibiotic resistance in P. aeruginosa isolates with a total of 40% and 50% MDR and XDR isolates respectively, and 70% carbapenem resistance. The prevalence of carbapenem conferring genes tested among carbapenem-resistant isolates was demonstrated as 65.7%.Conclusion: Due to the prevalence of P. aeroginosa strains carrying blaOXA-48 and blaNDM genes in our hospital, more attention and implementation of effective control measures against nosocomial infection are recommended.Keywords: Pseudomonas aeruginosa, carbapenems, encoding genes, antibiotics, drug susceptibility tes