Investigation of the effectiveness of metformin and various antibiotic combinations against pseudomonas aeruginosa isolates

Bacterial infections cause serious mortality and morbidity in humans. P. aeruginosa frequently causes infection in special patient groups such as cystic fibrosis patients, diabetic patients and patients in intensive care. P. aeruginosa infections are the focus of new treatment alternatives due to their frequent development of resistance to antibiotics and formation of biofilms. Recently, emphasis has been placed on combinations of antibiotics with drugs used for different indications. In this study the combined effects of metformin which is an antidiabetic drug used in the treatment of Diabetes mellitus with imipenem, ceftazidime, cefepime, ciprofloxacin and levofloxacin has been investigated. 50 P. aeruginosa isolates isolated from patients with cystic fibrosis come to Gaziantep University Faculty of Medicine Microbiology laboratory were included in the study. The susceptibilities of the isolates to antibiotics were investigated by the liquid microdilution method and the combined effect of metformin and antibiotics by the chequerboard synergy test. In our study, as a result of the chequerboard synergy test; synergistic between ceftazidime and metformin in 3 isolates (6%), partial synergistic in 11 (22%) isolates; while no synergistic effect was detected between cefepime and metformin in any isolate, partially synergistic in 23 isolates (46%); Synergistic between imipenem and metformin in 2 isolates (4%), partial synergistic in 5 isolates (10%); Synergistic effect between ciprofloxacin and metformin in 3 isolates (6%), partial synergistic effect in 3 isolates (6%), antagonist effect in 1 isolate (2%); synergistic effect was detected between levofloxacin and metformin in 1 isolate (2%) and a partial synergistic effect was detected in 6 isolates (12%). In our study, synergy and partial synergy were detected at different rates between metformin and antibiotics. It was concluded that new in-vitro studies and animal experiments are needed to determine to what extent metformin will increase the effect of antibiotics and whether it can be used as an antimicrobial molecule.