Effectiveness of Photokilling of Methicillin Resistant Staphylococcus aureus by Four Classes of Photosensitizers

Indianapolis, IN

Methicillin Resistant Staphylococcus aureus (MRSA) is an antibiotic resistant organism that can cause death. Photosensitizers and light can be used to inhibit the growth of bacterial cells. This experiment was conducted to determine the effectiveness of four photosensitizers in photokilling MRSA. The photosensitizers used in this study were Rose Bengal, Curcumin, Hematoporphyrin and Methylene Blue. MRSA cells were combined in a reaction dish with a photosenstizer and exposed to light for 60 minutes. Samples were removed at 0, 30 and 60 minutes then grown on TSA plates for 24 hours in the incubator. The MRSA cells were counted and percent survival was determined, using time zero as 100% survival. Rose Bengal was most effective at higher concentrations, and all photosensitizers were effective at photokilling MRSA to varying degrees over the 60 minute time period.