Figure 3.

Cytotoxic effects, as measured by XTT, of Pc 4-PDT in MSSA, HA-MRSA and CA-MRSA. Equal quantities of three S. aureus culture strains were treated overnight with 1.0 μM Pc 4 and then were irradiated with 2.0 J/cm² of 670–675 nm light. One hour following irradiation of Pc 4-loaded S. aureus, cultures were assayed for XTT reduction. H₂O₂ was used for a positive control. Values represent mean ± S.E. from at least three independent experiments. For all Pc 4-PDT-treated cultures, p < 0.005 vs. light alone control.