Infections caused by colistin-resistant P. aeruginosa strains pose a serious threat to public health. It is therefore urgent to find new strategies to deal with these bacterial infections. We aimed to investigate the efficacy and mechanisms of the colistin/resveratrol combination in eradicating colistin-resistant P. aeruginosa isolates and their biofilms both in vitro and in vivo. The results revealed that six clinically isolated colistin-resistant P. aeruginosa strains were multidrug resistant (MDR) strains, and resveratrol showed no antimicrobial activity against eight P. aeruginosa strains. Checkerboard assay and time-kill assays indicated that the combination therapy of resveratrol and colistin indicated a remarkable synergistic effect in vitro, and biofilm assays and SEM indicated synergistic antibiofilm activity. Furthermore, this combination could efficiently eliminate MDR bacteria in a murine infection model and improve the survival rate of Galleria mellonella. Fluorescence analysis, ALP, and β-galactosidase activity test results indicated that the colistin/resveratrol combination increased the membrane permeability of bacteria. In conclusion, our results may provide an efficient alternative pathway against colistin-resistant P. aeruginosa infections. IMPORTANCE P. aeruginosa is a ubiquitous Gram-negative opportunistic pathogen associated with a wide array of life-threatening acute and chronic infections. However, the improper and excessive use of antibiotics has contributed to the increasing emergence of multidrug-resistant (MDR) P. aeruginosa, even colistin-resistant strains, which presents a major challenge to clinical anti-infection treatment. Resveratrol, a naturally occurring polyphenolic antioxidant, can effectively slow down or avoid the occurrence and development of bacterial resistance and is expected to offer a promising strategy to overcome bacterial infections. In this study, colistin/resveratrol combination could synergistically damage the bacterial cell membrane, thereby inducing cell lysis while addressing the emergence of drug resistance. Moreover, this combination therapy may provide an efficient alternative pathway to combat the colistin-resistant P. aeruginosa in clinical practice.
Keywords: Pseudomonas aeruginosa; biofilm; colistin-resistant; resveratrol; synergy effect.