The effect of 20 μM methylene blue and laser light doses of 1.93 J/cm2, 3.86 J/cm2 and 9.65 J/cm2 on the lethal photosensitisation of EMRSA-16. An equal volume of either PBS (S-) (white bars) or 20 μM methylene blue (S+) (black bars) was added to 50 μL of the bacterial suspension and either kept in the dark (L-) or exposed to 665 nm laser light for 1, 2 and 5 minutes, corresponding to energy densities of 1.93 J/cm2, 3.86 J/cm2 and 9.65 J/cm2 (L+). After irradiation/dark incubation, samples were serially diluted and the surviving CFU/mL enumerated. Error bars represent the standard deviation from the mean. *** P < 0.001 (Mann Whitney U test). Experiments were performed three times in triplicate and the combined data are shown.