Effects of Imipenem, Tobramycin and Curcumin on Biofilm Formation of Pseudomonas aeruginosa Strains

Abstract

Aminoglycoside antibiotics and imipenem are reported to stimulate exopolysaccharide alginate production and cause an increased biofilm volume in Pseudomonas aeruginosa. Recently, some remarkable studies have been conducted on the effects of curcumin (Turmeric), which is the fenolic form of Curcuma longa plant, on virulence factors of P.aeruginosa. In this study, we aimed to investigate the effects of MIC and sub-MIC concentrations of imipenem, tobramycin, and curcumin on biofilm formation of P.aeruginosa strains. P.aeruginosa strains (n= 2) used in this study were isolated from deep oropharyngeal swab samples of two cystic fibrosis patients. Antimicrobial susceptibilities of the two strains to imipenem, tobramycin, and curcumin were investigated by broth microdilution method, and biofilm production was assessed by using crystal violet staining method. In our study, MIC values of imipenem, tobramycin and curcumin for strain-1 were 8 µg/ml, 8 µg/ml and 16 µg/ml, respectively, while those values were 4 µg/ml, 8 µg/ml and 16 µg/ml for strain-2. Biofilm optical density values of the strain-1 and strain-2 before being treated with the test substances were 0.937 and 0.313 (control: 0.090), respectively, Biofilm optical densities of the both strains showed an increase following treatment with MIC concentrations of imipenem and tobramycin. The treatment of the strains with MIC and sub-MIC concentrations of curcumin led to no significant increase in biofilm optical density. The data obtained in this study supported the promising inhibitory effect of curcumin on P.aeruginosa biofilms. However, further more comprehensive studies are required to provide satisfactory data about the use of curcumin to treat P.aeruginosa infections characterized by biofilm formation.