Evaluation of type II toxin-antitoxin systems, antibiotic resistance, and biofilm production in clinical MDR Pseudomonas aeruginosa isolates in Iraq

Background: Toxin-antitoxin systems (TAs) are stress response elements widespread in the bacterial genome and tightly involved in essential physiological processes including growth arrest, survival, biofilm formation, and bacterial persistence. Aim: We focused on characterize type-II TA system and it is an association with biofilm formation and antibiotic resistance in clinical Pseudomonas aeruginosa isolates from Baghdad hospitals. Methods: A total of 54 MDR P. aeruginosa isolates were identified by biochemical and molecular methods. All of the isolates were characterized for antibiotic susceptibility (disk diffusion method), biofilm formation (microtiter plates [MTP]) and the presence of different type-II TA systems including relBE, ccdAB, mazE, hipBE, and mqsR. Results: The high antibiotic resistance rate showed against augmentin 90.74%, ceftazidime 77.7%, tetracycline 77.7%, cefotaxime 74.0%, imipenem 31.48% and Meropenem 31.48%. Additionally, 16.66% (9/54) and 12.96% (7/54) of MDR P. aeruginosa isolates identified as ESBL-producers and Metallo-beta lactamase producers by phenotype. Biofilm formation observed in 90.74% (49/54) of the isolates. The PCR results in the detection of TAs system loci indicated that a high occurrence of TA genes was founded, 100% of isolates presented relBE and ccdAB genes, and 90.74% presented mqsR gene. The mazE and hipB genes were detected in 64.81% and 51.85% of the isolates respectively. Conclusions: A high occurrence of TA genes and antibiotic resistance rates within a low prevalence of ESBL and MBL producing in clinical MDR P. aeruginosa described in Iraqi hospitals. Also, our results indicated the first report of the presence of type II TAs among clinical P. aeruginosa isolates in Iraq.