Prevalence of Antibiotic Resistance and Class ۱ Integrons in Clinical and Environmental Isolates of Pseudomonas aeruginosa

Background: Many clinical isolates of Pseudomonas aeruginosa exhibit antibiotic-resistance and it is the main cause of hospital infections. Objectives: The current study aimed at evaluating the diversity of genes coding for antibiotic resistance in clinical and environmental isolates of P. aeruginosa in Hamadan, West of Iran. Methods: In the current cross sectional study, ۱۰۰ clinical and ۵۰ environmental isolates of P. aeruginosa were collected from October ۲۰۱۳ to May ۲۰۱۴. 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 ۱ integrons and genes encoding resistance to aminoglycoside antibiotics. The relationship between antibiotic resistance and integrons was tested by the ۲-tailed chi-square (χ ۲ ) or the Fisher exact tests. P values ≤ ۰.۰۵ were considered statistically significant. Results: The most common antibiotic resistance was to cotrimoxazole (۶۱.۳%). The least observed resistance was to meropenem (۹.۳%) and piperacillin /tazobactam (۱۲%). The result of minimum inhibitory concentration (MIC) for amikacin showed that ۲۰% of the strains were resistant, ۱۵% had intermediate resistance, and ۶۵% were sensitive. Class ۱ integrons were found in ۵۷% of the isolates. The aminoglycoside-resistance cassette included aadA (confers resistance to streptomycin and spectinomycin) and aphA۱ (encoded aminoglycoside ۳’-phosphotransferase) genes were the most prevalent in the isolates. Conclusions: Antibiotic resistance had a high prevalence in clinical isolates of P. aeruginosa and was commonly associated with class ۱ integrons. The knowledge of drug resistance patterns helps to apply effective antibiotic treatments and appropriate infection control measures to prevent the spread of infection in hospitals.