Enhanced in vitro antimicrobial activity of amphotericin B with berberine against dual-species biofilms of Candida albicans and Staphylococcus aureus

Aims: Multi-species biofilms formed by fungi and bacteria are clinically common and confer the commensal micro-organisms with protection against antimicrobial therapies. Previously, the plant alkaloid berberine was reported to show antimicrobial efficacy to eliminate Bacterial and Fungal biofilms. In this study, the combination of berberine and amphotericin B, an Antifungal agent, was evaluated against dual-species Candida albicans/Staphylococcus aureus biofilms.

Methods and results: Combinatorial treatment by berberine and amphotericin B significantly reduced the biomass and viability of residing species in biofilms. Moreover, morphological examination revealed hyphal filamentation of C. albicans and coadhesion between C. albicans/S. aureus were considerably impaired by the treatment. These effects coincided with the reduced expression of cell surface components and quorum-sensing-related genes in both C. albicans and S. aureus. Additionally, in C. albicans, the core transcription factors for controlling biofilm formation together with a crucial component of dual-species biofilms were also downregulated.

Conclusions: These results demonstrated synergistic effects of berberine and amphotericin B against C. albicans/S. aureus dual-species biofilms.

Significance and impact of the study: This study confirms the potential of berberine and amphotericin B for treating the C. albicans/S. aureus biofilms related infections and reveals molecular basis for the efficacy of combinatorial treatment.