Susceptibility of Ureaplasma urealyticum to Methylene Blue‐Mediated Photodynamic Antimicrobial Chemotherapy: An in vitro Study

The aim of this study was to detect the susceptibility of Ureaplasma urealyticum to methylene blue‐mediated photodynamic antimicrobial chemotherapy (PACT). Three U. urealyticum strains including the standard serotype 1 and 5, and a clinically collected strain were used in this study. Strains were first incubated in 96‐well culture plates in the presence of methylene blue with decreasing concentrations (from 1 to 0.015625 mg mL^?1) for 20 or 60 min, and then submitted to irradiation with a light‐emitting diode laser with a power density of 100 mW cm^?2 for 8, 17, 34 or 68 min. Regrowth of the strains was performed soon after irradiation. A significant inactivation effect was observed after PACT. Longer incubation time induced more extensive inactivation of U. urealyticum. No difference in response to PACT was observed between the two biovars of U. urealyticum. It was concluded that PACT had a significant inactivation effect on U. urealyticum, and it might be a promising alternative treatment for resistant U. urealyticum infections.