Evaluation of Antibiotic Resistance Pattern to imipenem and the Frequency of Class 1-3 integrons among Clinical Isolates of Pseudomonas aeruginosa in Southwestern of Iran

Background and Objectives: Pseudomonas aeruginosa is an opportunistic pathogen with the ability to cause severe nosocomial infections. P. aeruginosa infections are normally difficult to eradicate due to acquired resistance to many antibiotics. Recent appearance of carbapenem resistant P. aeruginosa isolates is considered a major healthcare problem. The present study aimed to investigate the occurrence class 1 integron and antibiotic susceptibility profiles of imipenem-sensitive and resistant clinical isolates of P. aeruginosa. Materials and Methods: In the current cross sectional study, 75 clinical isolates of P. aeruginosa were collected from Nemazee hospital. The standard disk diffusion method (SDD) was performed to test antibiotic susceptibility. All isolates were evaluated by the polymerase chain reaction (PCR) for the presence of class 1,2 and 3 integrons. Demographic and microbiological data were compared between imipenem susceptible and non-susceptible isolates by the SPSS software.Results: Antibiotic susceptibility results revealed that 43 (57.3%) isolates were susceptible and 32 (42.7%) of them were non-susceptible to imipenem. The highest resistance to imipenem was seen in the surgical ward. PCR amplification showed that 39(52%) and 13(17.3%) of P. aeruginosa strains carried int1and int2, respectively, but none of them harbored int3 genes. The distribution of int1 gene was highest in urine (69.2%), whereas int2 gene was respiratory tract isolates (34.6%). Conclusion: The high frequency of imipenem resistance was seen among our P. aeruginosa isolates that may be related to the presence of class 1 integron gene. The role of these transferable genetic agents has been proven in the creation of resistance. Since carbapenems are considered as the last drugs used for the treatment of P. aeruginosa infections, it is crucial to screen imipenem non-susceptible isolates in infection control and optimal therapy.