In Vitro Antimicrobial Efficacy of Riboflavin and Ultraviolet Light on Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa

PURPOSE: Ultraviolet (UV) light and riboflavin has been developed as a collagen cross-linking treatment for corneal ectasia. This treatment has also been used to treat infectious corneal ulcers with apparent favorable results. In this experiment, the antibacterial action of riboflavin alone, UV light alone, and the combination of riboflavin and UV light was tested on Staphylococcus aureus, methicillin-resistant S aureus (MRSA), and Pseudomonas aeruginosa. METHODS: Thirty agar plates with S aureus overlays were used. Ten plates were exposed to riboflavin (0.1% solution in dextran) alone, 10 plates were exposed to UV light (365 nm) alone, and 10 plates were exposed to a combination of riboflavin and UV light. Fifteen agar plates with MRSA and 15 plates with P aeruginosa were tested. Five plates of each group were exposed to riboflavin, 5 plates of each group were exposed to UV light alone, and 5 plates of each group were exposed to a combination of riboflavin and UV light. All plates were incubated for 24 hours and then analyzed. RESULTS: All plates exposed to riboflavin alone showed no bacterial death. All S aureus and MRSA plates exposed to UV light alone showed no bacterial growth. Three of five P aeruginosa plates exposed to UV light alone showed no bacterial death; two of five P aeruginosa plates exposed to UV light alone showed minimal inhibition. All plates exposed to the combination of riboflavin and UV light showed bacterial death. CONCLUSIONS: Riboflavin in combination with UV light is an effective modality to eradicate the bacteria S aureus, MRSA, and P aeruginosa. [J Refract Surg. 2009;25: S799-S802.] doi:10.3928/1081597X-20090813-07