Photodynamic therapy as a new approach to Trichomonas vaginalis inactivation

The emergence of nitroimidazole resistant isolates has been an aggravating factor in the treatment of trichomoniasis, the most common non-viral sexually transmitted disease in the world. This highlights the importance of new technologies that are safe, effective, and have minor side effects or resistance. Hence, we evaluated the effectiveness of photodynamic therapy on the inactivation of Trichomonas vaginalis in vitro. We used methylene blue as a photosensitizing substance, and a light-emitting diode (LED) for irradiation of metronidazole sensitive and resistant strains. Our results showed that only the presence of light did not interfere with parasite growth; however, methylene blue isolated or associated with light inhibited 31.78% ± 7.18 and 80.21% ± 7.11 of the sensitive strain, respectively, and 31.17% ± 4.23 and 91.13% ± 2.31 of the resistant strain, respectively. The high trichomonicidal activity of the photodynamic therapy, associated with low cost and ease of application, signalize its great therapeutic potential not only when conventional treatment fails, but also routinely in women with trichomoniasis.