The Inhibitory Effect of Thioridazine on adeB Efflux Pump Gene Expression in Multidrug-Resistant Acinetobacter baumannii Isolates Using Real Time PCR

Background: the purpose of the present study was to investigate the antimicrobial effects of berberine and thioridazine, as well as their effect on the gene expression of the adeabc efflux pump system in multidrug-resistant (mdr) acinetobacter bau-mannii (a. baumannii) isolates. methods: this study was carried out in five mdr clinical isolates of a. baumannii and a sample of standard strain (a. baumannii ptcc1797). the effect of minimum inhibi-tory concentration (mic) and the minimum bactericidal concentration (mbc) of berberine, thioridazine, and ciprofloxacin alone and their combination on a. bau-mannii was evaluated by broth microdilution method. also, their effect on the expres-sion of adeb efflux pump gene was evaluated using real time pcr method. results: the mic of thioridazine, berberine, ciprofloxacin+thioridazine, ciprofloxacin+ berberine, thioridazine+berberine, and ciprofloxacin+thioridazine+berberine on mdr a. baumannii isolates was 64, 256, 128, 256, 128, and 128 μg/ml, respectively. the results showed that treatment of strains with thioridazine alone and in combination with berberine and ciprofloxacin significantly (p<0.05) decreased the expression of adeb ef-flux pump gene. conclusion: due to the inhibitory effects of thioridazine on bacterial isolates and adeb efflux pump gene, this compound can be used as a potential antimicrobial agent against mdr a. baumannii.