Antimicrobial Efficacy of Riboflavin/UVA Combination (365 nm) In Vitro for Bacterial and Fungal Isolates: A Potential New Treatment for Infectious Keratitis

• Published in: Investigative ophthalmology & visual science Vol. 49; no. 8; pp. 3402 - 3408
• Main Authors: Martins, Suy Anne R, Combs, Juan Castro, Noguera, Guillermo, Camacho, Walter, Wittmann, Priscila, Walther, Rhonda, Cano, Marisol, Dick, James, Behrens, Ashley
• Format: Journal Article
• Language: English
• Published: Rockville, MD ARVO 01.08.2008; Association for Research in Vision and Ophtalmology
• Subjects: Bacteria - drug effects; Bacteria - radiation effects; Biological and medical sciences; Candida albicans - drug effects; Candida albicans - radiation effects; Colony Count, Microbial; Combined Modality Therapy; Corneal Ulcer - drug therapy; Corneal Ulcer - microbiology; Corneal Ulcer - radiotherapy; Diseases of cornea, anterior segment and sclera; Drug Resistance, Bacterial; Drug Resistance, Multiple; Eye and associated structures. Visual pathways and centers. Vision; Flavin Mononucleotide - pharmacology; Fundamental and applied biological sciences. Psychology; Fungi - drug effects; Fungi - radiation effects; Medical sciences; Ophthalmology; Photosensitizing Agents - pharmacology; Pseudomonas aeruginosa - drug effects; Pseudomonas aeruginosa - radiation effects; Staphylococcus aureus - drug effects; Staphylococcus aureus - radiation effects; Staphylococcus epidermidis - drug effects; Staphylococcus epidermidis - radiation effects; Streptococcus pneumoniae - drug effects; Streptococcus pneumoniae - radiation effects; Ultraviolet Rays; Ultraviolet Therapy; Vertebrates: nervous system and sense organs; Keratitis; UVA radiation; Vitamin; Riboflavin; Keratopathy; B-Vitamins; In vitro; Antimicrobial agent; Infection; Eye disease; Treatment; Bacteriosis; Bacteria; Ophthalmology; Anterior segment disease
• ISSN: 0146-0404; 1552-5783; 1552-5783
• DOI: 10.1167/iovs.07-1592

To demonstrate the antimicrobial properties of riboflavin/UVA (365 nm) against common pathogens. One group of bacteria (Pseudomonas aeruginosa [PA], Staphylococcus aureus [SA], and Staphylococcus epidermidis [SE]) was tested by using Kirby-Bauer discs with (1) empty disc (Control - C); (2) riboflavin 0.1% (B2); (3) riboflavin 0.1% previously activated by UVA (B2'); (4) UVA alone (UVA); (5) group 2+additional UVA exposure (UVA+B2); and (6) group 3+additional UVA exposure (UVA+B2'). In addition, another group of microbes was tested with the same approach: methicillin-resistant S. aureus (MRSA), multidrug-resistant P. aeruginosa (MDRPA), drug-resistant Streptococcus pneumoniae (DRSP), and Candida albicans (CA). The mean growth inhibition zone (GIZ) in square millimeters was measured around the discs. The mean standard deviation (MSD) was calculated to be 3.65 when alpha = 0.01. A mean deviation (MD) > MSD indicates a significant difference. In the first group, the GIZ was significantly greater after UVA (MD = 14.30), UVA+B2 (MD = 39.61), and UVA+B2' (MD = 40.45) when compared with C, B2, and B2'. UVA alone was less effective than UVA+B2 (MD = 25.31) and UVA+B2' (MD = 26.15). The second group demonstrated increased GIZ in UVA (MD = 6.98), UVA+B2 (MD = 17.80), and UVA+B2' (MD = 21.15) when compared with C, B2, and B2'. UVA alone was less effective against the second group of bacteria than was UVA+B2 (MD = 10.82) and UVA+B2' (MD = 14.17). CA did not show any GIZ after treatment. Riboflavin/UVA was effective against SA, SE, PA, MRSA, MDRPA, and DRSP, but was ineffective on CA and has the potential for use in treatment of microbial keratitis in the future.