Molecular epidemiology of carbapenem resistance in Acinetobacter baumannii isolates in Shahid Mohammadi Hospital, Bandar Abbas, Iran

Introduction: Acinetobacter baumannii is a major cause of nosocomial infections which affect mainly disabled patients in intensive care units. The bacteria may acquire resistance to antibiotics and hence can seriously endanger antibiotic therapy. The most important problem facing treatment of A. baumannii is increasing reports of resistance to a wide range of antibiotics, including carbapenems, as the treatment of choice for this bacterial infection. Oxacillinase-type carbapenemases belonging to Class D beta-lactamases (OXA-type) are among the main mechanisms of reasons for resistance to carbapenems. The present study aimed to evaluate the patterns of antibiotic resistance and the prevalence of carbapenemase genes of oxacillinases in clinical isolates of A. baumannii in a hospital in Bandar Abbas, Iran. Methods: A total of 69 isolates of Acinetobacter were collected within two years from different samples of patients’ bodies in the Shahid Mohammadi Hospital of Bandar Abbas. The isolates genus was identified using biochemical methods and A. baumannii species using PCR. Antibiotic resistance to imipenem and meropenem was identified through disk diffusion method. OXA-type carbapenem resistance genes were identified by multiplex PCR. The data were statistically analyzed through the chi-square test using SPSS 17, and the graphs were plotted using Excel. Results: Out of 69 Acinetobacter isolates, 57 (82.6%) had blaOXA-51 gene and were identified as A. baumannii. Antibiogram showed a significant resistance to beta-lactams and other antibiotics studied. The resistance percentage of the isolates to imipenem and meropenem antibiotics were 29.8% and 70.2%, respectively. Although all isolates were susceptible to colistin and polymyxin B, 78.9% of isolates had blaoxa-23, 8.8% blaOXA-24, and 1.7% blaOXA-58 genes. Conclusion: This study showed that beta-lactamase OXA-23 gene is the common identified known carbapenemase among carbapenem-resistant A. baumannii in Bandar Abbas Hospital. Evaluation of antibiotic-resistant genes in A. baumannii is necessary to further control dissemination of antibiotic resistance genes