ABSTRACT
            Background and objectives: The present study was conducted to detect class 1 integrons and evaluate antibiotic susceptibility patterns among clinical isolates of P. aeruginosa.
            Methods: Sixty clinical samples from blood, tracheal wounds, burns and urinary tract infections were collected from three general hospitals in Tehran, Iran. Culture of specimens was performed on common bacteriological culture media. Bacteria were  identified based on mobility, pigment production, growth at 42 ^oC, and oxidase and catalase tests. Overall, 21 P.  aeruginosa strains were isolated. Antimicrobial susceptibility of was evaluated via the disk diffusion method (Kirby-Bauer) according to the CLSI guidelines. Presence of the intI1, sul1, aadA2 and aadB gene cassettes was investigated using PCR. The collected data were analyzed using SPSS software (version 21).
            Results: The most effective antimicrobial agents against P. aeruginosa isolates were tetracycline and gentamicin. All P. aeruginosa isolates were multidrug re­sistant. Moreover, the intI1, sul1, aadA2 and aadB genes were found in 90.5%, 90.5%, 47.6% and 19% of the P. aeruginosa isolates, respectively.
            Conclusion: The results indicate that the presence of aadB, aadA2 and sul1 gene cassetes may play an important role in the dissemination of antimicrobial resistance determinants.
          Keywords: Pseu­domonas aeruginosa, integron, multidrug resistance.