Molecular Detection of Type II Toxin-Antitoxin Systems and their Association with Antibiotic Resistance and Biofilm Formation in Clinical Acinetobacter baumannii Isolates of Burn Patients

 Background and purpose: Burn wounds are a good host for infections. Acinetobacter baumannii is an opportunistic bacterium in patients with burn infections. Toxin-antitoxin systems (TAS) are genetic elements that are essential for antibiotic resistance and biofilm formation in bacteria, including higBA and relBE TA systems. The present study aimed to investigate the frequency of higBA and relBE genes in A. baumannii strains isolated from burn wound infection as well as the association between genetic elements and antibiotic resistance and biofilm formation. Materials and methods: In this descriptive cross-sectional study, 139 A. baumannii isolates were collected from burn wounds of patients hospitalized in a burn center in Isfahan, Iran. The isolates were identified and confirmed through biochemical and molecular tests. Antibiotic susceptibility testing was performed via disk diffusion method and biofilm production was detected by microtiter plate assay. Presence of higBA and relBE TA system genes was investigated by PCR. Results: Out of 139 A. baumannii isolates, 114 were multi-drug resistant (MDR) and able to form biofilm. relBE and higBA genes were observed in 94.73% and 8.77% of the isolates, respectively. Significant correlations were found between the presence of relBE and higBA genes and resistance to imipenem and levofloxacin (P<0.05). There were no significant correlations between presence of relBE and higBA genes and biofilm formation (P>0.05). Conclusion: In this study, the number of MDR A. baumanni strains was significantly higher compared to previous studies and most species had the ability to form biofilms. According to the association between TA genes and antibiotic resistance, further studies are needed on the TA systems.