Introduction: This study aimed to compare the antimicrobial effects of thymol/ceftazidime between
Pseudomonas aeruginosa and
Acinetobacter baumannii bacteria. Material and methods:
Antimicrobial effects of thymol/ceftazidime were performed first individually and then combined on
Pseudomonas aeruginosa ATCC۲۷۸۵۳ and
Acinetobacter baumannii ATCC ۱۹۶۰۶ by the MIC-MBC method. Therefore, the antimicrobial effects of the compounds that had synergistic effects were performed on Ten to eighteen clinical strains using the MIC-MBC method. Identification of chemical bonds, functional groups, and molecular interactions of the mentioned compounds were investigated with an FTIR device. Checkered method, time killing curve, and biofilm inhibition on
Pseudomonas aeruginosa ATCC۲۷۸۵۳ and
Acinetobacter baumannii ATCC ۱۹۶۰۶, investigation of cytotoxicity on red blood cells (RBCs) by hemolysis method and human skin fibroblast cells (Ffk) by MTT method were performed. Finally, the results of the tests were compared between the two bacteria. Results: The results of this study showed that the antimicrobial activity of thymol/ceftazidime (۶۴/۱۶ µg/mL) against clinical and ATCC strains of P. aeruginosa was better than that against A. baumannii (۵۱۲/۱۲۸ µg/mL). In the examination with the FTIR device, both compounds had bonds of OH carbohydrates proteins, polyphenols, C=O Amide I band, C-O-C polysaccharide, C-N amide III band, but one band named C=C conjugated, C=C in both compounds showed the connection between thymol with ceftazidime. The biofilm inhibition effects of thymol/ceftazidime were better in P. aeruginosa (۸۲.۶۹%) than in A. baumannii (۲۴.۴۱%). The bacterial lethality time curve at lower concentrations and times showed that this compound was better in P. aeruginosa than in A. baumannii. Cytotoxicity of synergistic compound on RBCs and human Ffk cells was not different and was lower than that of Triton X-۱۰۰. Discussion: Considering the antibiotic resistance of ceftazidime in the treatment of diseases caused by the aforementioned bacteria, the combination of thymol/ceftazidime in this study and P. aeruginosa showed better antimicrobial, anti-biofilm effects and bacterial killing time than A. baumannii. This combination can be used as a new drug in patients after further studies.
