In Vitro Antifungal Efficacy of Riboflavin/uva (365 Nm) Combination on Different Fungal Keratitis Isolates

Abstract

Purpose: : To demonstrate the antimicrobial properties of riboflavin/UVA (365 nm) against fungal pathogens.

Methods: : The antimicrobial properties of riboflavin/UVA (365 nm) were tested on three groups of fungi selected from a panel of human keratomycosis isolates: Candida albicans (CA), Fusarium sp (FS) and Aspergillus fumigatus (AF). The antimicrobial properties were tested by using Kirby-Bauer discs with (1) empty disc (Control - C), (2) riboflavin 0.1% alone (R), (3) UVA alone for 1 hour (UVA), (4) riboflavin 0.1% and additionnal UVA exposure for 1 hour (R+UVA), (5) Amphotericin B alone (A), (6) Amphotericin B and riboflavin 0.1% (A+R), (7) Amphotericin B and UVA for 1 hour (A+UVA), and (8) Amphotericin B and riboflavin 0.1% and additionnal UVA exposure (A+R+UVA). The mean growth inhibition zone (GIZ) in square millimeters was measured around the discs. Descriptive statistics are expressed as mean and SD. A two-way ANOVA test was used for the analysis.

Results: : CA, FS and AF did not show any GIZ after treatment without previously Amphotericin B medication. However, the GIZ was significantly greater after riboflavin/UVA and pretreatment with amphotericine B (A+R+UVA) for CA (p=0,002), FS (p=0,007) and AF (p=0,03) when compared with A, A+R and A+UVA.

Conclusions: : Amphotericin B is believed to interact with fungi membrane sterols to produce aggregates that form transmembrane channels. Previously treatment with amphotericine B allowed Riboflavin/UVA effectiveness against CA, FS and AF. Further investigations are needed to determine in vivo efficacy of this therapeutic approach on severe keratomycosis.

Keywords: cornea: basic science • drug toxicity/drug effects • radiation damage: light/UV