Uptake of PpIX in the reference and clinical isolates of Staphylococcus aureus. Uptake of PpIX (μg/mg cell protein) by S. aureus clinical isolates and reference strains. Beneath, the names clinical strains, the name of the parental strain and its sod isogenic mutants are indicated. Concentration of PS was 10 μM and 50 μM. PS was incubated for 30 min., washed, dissolved in 0.1 M NaOH-1% SDS, and fluorescence measured as described in the text. Values are means of three separate determinations, and bars are SD.