Investigation of Class I, II and III Integrons among Acinetobacter Strains Isolated from Ventilator-Associated Pneumonia Patients in Intensive Care Unit of Rasoul Akram Hospital in Tehran, Iran

Background: Multi-drug resistant strains of Acinetobacter spp. have created therapeutic problems worldwide. The objective of this study was to detect integrons in Acinetobacter spp. isolates from Ventilator-Associated Pneu- monia patients using PCR method. Methods: A total 51 Bronchoalveolar lavage samples were obtained from patients in ICU and examined for Acinetobacter spp. infection by biochemical and PCR methods using blaOXA51-like primers. Antimicrobial susceptibility testing was performed using disk diffusion and MIC methods. Results: Among 51 patients with VAP (62.7% males, 35.2% females, mean age 53 year), 50 (98%) were positive, with a high prevalence of gram-nega- tive bacteria, mainly Acinetobacter spp. (70%), from which A. baumani was detected in 34 (68%) and A. lwoffii in 1 (2%) of isolates. More than 90% of isolates were resistant to imipenem, piperacillin+tazobactam, third genera- tion cephalosporins and gentamicin, while the most effective antibiotic was colistin (100%). The correlation coefficient between disk diffusion and MIC was 0.808 (p = 0.001). Three Acinetobacter isolates (8%) harbored integrase I gene but none of isolates contained Class II or III integrons. Conclusion: The results showed that colistin was an effective antibiotic and can be used for treatment of patients in ICU. Due to the high number of MDR isolates lacking Integrons it can be concluded that although class I in- tegrons are important among clinical isolates of A. baumannii, they have no significant role in dissemination of antibiotic resistance genes in Rasoul Akram Hospital in Tehran, Iran. The presence of IntI in A. lwoffii may be related to transfer of integron to A. baumannii which can be considered as an important threat for hospitalized patients.