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Table 2 The effect of light dose on the activity of α-haemolysin when treated with 20 μM methylene blue

From: Inactivation of staphylococcal virulence factors using a light-activated antimicrobial agent

Light Dose (J/cm2) Haemolytic titre
Haemolytic titre
0 1/512 1/512
1.93 1/256 < 1/2
3.86 1/256 < 1/2
9.65 1/256 < 1/2
  1. An equal volume of either 20 μM methylene blue (S+) or PBS (S-) was added to S. aureus α-haemolysin and samples were either exposed to laser light doses of 1.93 J/cm2, 3.86 J/cm2 and 9.65 J/cm2 (L+) or kept in the dark (L). After irradiation/dark incubation, samples were serially diluted and an equal volume of 4% rabbit erythrocytes was added. Following incubation in the dark at 37°C for one hour, the haemolytic titre was recorded. The haemolytic titre is the highest dilution giving rise to haemolysis. Experiments were performed twice in triplicate and a representative experiment is shown.