Pore formation as caused by peptide addition was determined by measuring ATP leakage from the bacterial cell using a bioluminescence assay as previously described. S. aureus 8325–4 was grown in TSB at 37°C overnight and then re-inoculated in TSB at 37°C. S. aureus was harvested (3000 RPM, 10 min) at mid-exponential phase (OD546 of 2.5 ± 0.1), washed once in 50 mM potassium phosphate buffer pH 7.0 and once in 50 mM HEPES buffer pH 7.0. The pellet was resuspended in 50 mM HEPES pH 7.0 to a final OD546 of 10. Bacteria were stored on ice and used within 5 h. Bacteria were energized in 50 mM HEPES (pH 7.0) with 0.2% (w/v) glucose and treated with various concentrations of LP5 up to a concentration of 1000 μg/ml.