Chinese herbal medicines and nutraceuticals inhibit Pseudomonas aeruginosa biofilm formation

Pseudomonas aeruginosa is a major biofilm-forming, opportunistic pathogen. Tolerance to antimicrobial agents due to biofilm formation may lead to the emergence of antimicrobial-resistant bacterial strains. Thus, adjunctive agents that can inhibit biofilm formation are necessary to enhance the therapeutic efficacy of antimicrobial agents. In this study, we evaluated the anti-biofilm formation activity of selected Chinese herbal medicines and nutraceuticals, which are commercially available in Japan. Among the eight agents evaluated for their potential to inhibit biofilm formation, Eiekikaryu S, Iribakuga and Hyakujunro significantly reduced P. aeruginosa biofilm formation (P <0.05) without inhibiting bacterial growth. Additionally, the expression of biofilm-associated genes (rhlR, rhlA and lasB) in P. aeruginosa was significantly suppressed by Eiekikaryu S, Iribakuga and Hyakujunro (P <0.001). Our findings indicate that some Chinese herbal medicines and nutraceuticals can be potential adjunctive agents for antimicrobial therapy against P. aeruginosa .