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

BMC Microbiology

Table 1 The effect of treatment of α-haemolysin with different concentrations of methylene blue and a laser light dose of 1.93 J/cm².

Concentration of methylene blue (μM)	Haemolytic titre L-	Haemolytic titre L+
1	1/1024	1/256
5	1/1024	1/2
10	1/1024	< 1/2
20	1/512	1/2

An equal volume of either 1, 5, 10 and 20 μM methylene blue or PBS was added to S. aureus α-haemolysin and samples were either exposed to 1.93 J/cm² laser light (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 defined as the highest dilution giving rise to haemolysis. Experiments were performed twice in duplicate and a representative experiment is shown.

ISSN: 1471-2180