Antimicrobial efficacy of riboflavin/UVA combination (365 nm) in vitro for bacterial and fungal isolates: a potential new treatment for infectious keratitis.

Abstract

PURPOSE:

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

METHODS:

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.

RESULTS:

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.

CONCLUSIONS:

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.

• Authors: Suy Anne R Martins, Juan Castro Combs, Guillermo Noguera, Walter Camacho, Priscila Wittmann, Rhonda Walther, Marisol Cano, James Dick, Ashley Behrens
• Journal: Investigative ophthalmology & visual science (Invest Ophthalmol Vis Sci) Vol. 49 Issue 8 Pg. 3402-8 (Aug 2008) ISSN: 1552-5783 [Electronic] United States
• PMID: 18408193 (Publication Type: Comparative Study, Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Photosensitizing Agents
• Flavin Mononucleotide

Topics

• Bacteria (drug effects, radiation effects)
• Candida albicans (drug effects, radiation effects)
• Colony Count, Microbial
• Combined Modality Therapy
• Corneal Ulcer (drug therapy, microbiology, radiotherapy)
• Drug Resistance, Bacterial
• Drug Resistance, Multiple
• Flavin Mononucleotide (pharmacology)
• Fungi (drug effects, radiation effects)
• Photosensitizing Agents (pharmacology)
• Pseudomonas aeruginosa (drug effects, radiation effects)
• Staphylococcus aureus (drug effects, radiation effects)
• Staphylococcus epidermidis (drug effects, radiation effects)
• Streptococcus pneumoniae (drug effects, radiation effects)
• Ultraviolet Rays
• Ultraviolet Therapy