Cold atmospheric plasma inactivates Aspergillus flavus and Fusarium keratoplasticum biofilms and conidia in vitro

Abstract

Introduction. Aspergillus flavus and Fusarium keratoplasticum are common causative pathogens of fungal keratitis (FK), a severe corneal disease associated with significant morbidity and vision loss. Escalating incidence of antifungal resistance to available antifungal drugs poses a major challenge to FK treatment. Cold atmospheric plasma (CAP) is a pioneering nonpharmacologic antimicrobial intervention that has demonstrated potential as a broad-spectrum antifungal treatment. Gap statement. Previous research highlights biofilm-associated resistance as a critical barrier to effective FK treatment. Although CAP has shown promise against various fungal infections, its efficacy against biofilm and conidial forms of FK pathogens remains inadequately explored. Aim. This study aims to investigate the antifungal efficacy of CAP against clinical fungal keratitis isolates of A. flavus and F. keratoplasticum in vitro. Methodology. Power parameters (22–27 kVpp, 300–400 Hz and 20–80 mA) of a dielectric barrier discharge CAP device were optimized for inactivation of A. flavus biofilms. Optimal applied voltage and total current were applied to F. keratoplasticum biofilms and conidial suspensions of A. flavus and F. keratoplasticum. The antifungal effect of CAP treatment was investigated by evaluating fungal viability through means of metabolic activity, c.f.u. enumeration (c.f.u. ml−1) and biofilm formation. Results. For both fungal species, CAP exhibited strong time-dependent inactivation, achieving greater than 80 % reduction in metabolic activity and c.f.u. ml−1 within 300 s or less, and complete inhibition after 600 s of treatment. Conclusion. Our findings indicate that CAP is a promising broad-spectrum antifungal intervention. CAP treatment effectively reduces fungal viability in both biofilm and conidial suspension cultures of A. flavus and F. keratoplasticum, suggesting its potential as an alternative treatment strategy for fungal keratitis.