Prevalence of class I, II and III integrons in multidrug-resistant and carbapenem-resistant Pseudomonas aeruginosa clinical isolates

Integrons are mobile genetic elements located on transposons, plasmids and bacterial chromosomes. These elements play a key role in spreading resistance gene cassettes to various disinfectants and antibiotics and facilitate the global antibiotic resistance crisis. The present study was aimed to evaluate the prevalence of class I, II and III integrons in multidrug-resistant (MDR) and carbapenem-resistant Pseudomonas aeruginosa (P. aeruginosa) strains isolated from patients referring to Ardabil hospitals. A total of 103 confirmed P. aeruginosa clinical isolates were included in this study (collected between June 2019 and April 2021). Antibiotic resistance pattern was assessed using Kirby-Bauer disk diffusion method on Mueller–Hinton agar. The presence of intI1, intI2 and intI3 genes was detected using the set of specific primers by polymerase chain reaction (PCR) assay. The total frequency of class I integron gene was 58.3% in P. aeruginosa isolates. No class II and III integrons were detected in P. aeruginosa isolates. The prevalence of MDR P. aeruginosa strains was 54.3% and the rate of class I integron was significantly higher in MDR P. aeruginosa than non-MDR isolates (76.7% vs. 23.3%) (p < 0.05). Additionally, the frequency of class I integron gene among carbapenem-resistant P. aeruginosa strains was as follows: doripenem 44.7%, imipenem 85.5% and meropenem 62.7% (p < 0.05). Our results revealed that class I integron was the most prevalent integrons among clinical isolates of drug-resistant P. aeruginosa in Ardabil hospitals. These integrons seem to play a significant role in dissemination of drug resistance genes and the emergence of antibiotic-resistant strains, particularly MDR and carbapenem-resistant ones.