Correlation between the Presence of Toxin-Antitoxin System Genes and Ability of Biofilm Formation and Antibiotic Resistant in Clinical Isolates of Acinetobacter baumannii

Background and Objectives: Toxin-antitoxin systems are common in bacteria and in archaea.TA systems are composed of a protein toxin and its cognate antitoxin, which can be an RNA or a protein depending on the type. TA systems are subdivided into six various types. Antitoxin proteins inhibit toxin through direct interaction with toxin or effect on their targets. Type II TA systems were first discovered in the mid-1980s. Type II systems include RelB, MazE, HigA and so on. These genes are located on the plasmids in the A. baumannii and in studies on these genes, their association with biofilm formation and antibiotic resistance in some bacteria has been established. The aim of this study was to investigate the relationship between antibiotic resistance and genes HigBA and RelBE. Materials and Methods: Biochemical and molecular tests were used for identification of the A. baumannii and antibacterial susceptibility test was performed using disk diffusion methods. Screening for biofilm formation was done by microtitre plate assay. The HigBA and RelBE toxin-anti toxin genes were detected in the isolates by PCR molecular method. All statistical analyses were done by means of SPSS software version 24.0. Results: the results of PCR on HigBA gene showed that 11of the isolates possess the gene. The results of PCR on RelBE gene showed that 134 of the isolates possess the gene. In the present study, there was no significant relationship between biofilm and available genomes but there was a significant relationship between imipenem susceptibility and available genome (p=0.022) Conclusion: The high antibiotic resistance of A. baumannii has caused major problems in the treatment of patients. Biofilm is one of the effective factors on increasing antibiotic resistance in isolates. Therefore, factors affecting increased antibiotic resistance as well as increased biofilm production complicate treatment-related problems in these resistant strains. Controlling the expression of these genes (HigBA, RelBE) is an effective step in the relative control of increased resistance in such strains.