Multiple carbapenemase gene production by Acinetobacter baumannii isolates from burn patients in Iran

Objective: Acinetobacter baumannii is among the major Gram-negative nosocomial pathogens, and their antibiotic resistance has spread extensively; especially in burn settings. Methods: A total of 300 clinical isolates of A. baumannii were collected from burn patients hospitalized in burn settings. The isolates were examined for antimicrobial susceptibility testing by the disc diffusion method. The class D (blaOXA-51-like, blaOXA-23-like, blaOXA-58-like and blaOXA-24-like) and class B (encoded by blaVIM and blaSIM) carbapenemase genes were investigated by multiplex PCR. Results: A high level of carbapenem resistance was observed among isolates, but none of them were resistant to colistin. Among carbapenem-resistant A. baumannii, previous antibiotic consumption was significantly higher (significant risk factor for carbapenem-resistant A. baumannii acquisition) than other risk factors (P = 0.0123), whereas older age of patients was not significantly higher among other ranges in multivariate analysis by analysis of variance (ANOVA test). The blaOXA-51-like gene was the predominant gene, followed by blaOXA-23-like, blaOXA-24-like, blaOXA-58-like, blaSIM,blaNDM and blaVIM genes being 66, 35.33, 22, 14, 1.33, 1.33 and 13.33%, respectively. Furthermore, the co-existence of blaOXA-51-like/blaOXA-23-like, blaOXA-51-like/blaOXA-23-like/blaOXA-24-like and blaOXA-51-like/blaOXA-24-like were 22.67, 12 and 11.33%, respectively. Conclusion: A high level of class D and class B carbapenemases among A. baumannii strains in the burn settings is a crisis in the eradication of infections caused by MDR, XDR and PDR strains. Therefore, the uncontrolled consumption of last-line antibiotics should be restricted and infection control strategies must be implemented accurately.