Figure 6. . Effect of regrowth in medium after antimicrobial photodynamic inactivation in phosphate-buffered saline.

Bacterial cells (Escherichia coli or MRSA was incubated in phosphate-buffered saline with demeclotetracycline or doxycycline at 5 μM, or with methylene blue at 8 μM (for E. coli UTI89) or 4 μM (for MRSA), and exposed to 10 J/cm² of the appropriate light (BL for demeclotetracycline; UV A for doxycycline; red light for methylene blue). The samples were assayed for colony-forming unit and then added to fresh growth medium and incubated overnight, and the colony-forming units were determined again.

BL: Blue light; DMCT: Demeclocycline; DOTC: Doxycycline; Ec: Escheria coli; MB: Methylene blue; MRSA: Methicillin-resistant Staphylococcus aureus; PDT: Photodynamic therapy; RL: Red light; UVA: Ultra violet A.

Reproduced from [57].