Use of 401 ± 5 nm Blue Light-Emitting Diode in the Prevention of Recurrent Bacterial Vaginosis: A Randomized Clinical Trial

Bacterial vaginosis (BV) is the most prevalent vaginal dysbiosis among women of reproductive age and is associated with several adverse gynecological and obstetric outcomes. Although effective antimicrobial treatments are available, recurrence remains frequent, with recurrence rates exceeding 50% within 12 months after treatment. The pathophysiology of BV involves disruption of the normal Lactobacillus-dominated vaginal microbiota and proliferation of anaerobic and facultative anaerobic bacteria, including Gardnerella vaginalis, Fannyhessea vaginae, Mobiluncus spp., Prevotella spp., and other bacterial taxa. These microorganisms may form polymicrobial biofilms on the vaginal epithelium, which can contribute to persistence of the condition and recurrence after antimicrobial treatment. Metronidazole is an established treatment for bacterial vaginosis. However, the high recurrence rate following conventional treatment highlights the need for complementary therapeutic approaches. Blue light has demonstrated antibacterial activity in previous experimental studies. One proposed mechanism involves the excitation of endogenous microbial photosensitizing chromophores, such as porphyrins and flavins, resulting in the production of reactive oxygen species that may exert cytotoxic effects on microorganisms. Previous clinical research has also investigated the safety of 401 ± 5 nm blue LED therapy on healthy vaginal mucosa. This randomized clinical trial will investigate whether the addition of 401 ± 5 nm blue light-emitting diode (LED) photobiomodulation to conventional oral metronidazole therapy can reduce the recurrence of bacterial vaginosis compared with oral metronidazole alone. The study will also assess the diagnostic performance of the Amsel and Nugent criteria for bacterial vaginosis. Clinical and laboratory assessments will be performed during the study according to standardized procedures, including gynecological examination, vaginal pH measurement, amine testing, fresh microscopy, and Gram staining. Participants diagnosed with bacterial vaginosis will receive standard oral metronidazole treatment. Participants allocated to the intervention group will additionally undergo eight sessions of blue LED therapy. The LED treatment will be administered at the study site by a trained professional using the study-specific device. Participants will be followed after treatment to assess clinical and laboratory findings and the occurrence of recurrent bacterial vaginosis. Statistical analyses will be performed according to the prespecified study protocol, using a significance level of 5%. The study is intended to provide preliminary clinical evidence regarding the potential role of blue LED photobiomodulation as an adjunct to conventional antimicrobial therapy for reducing bacterial vaginosis recurrence. The findings may support the development of larger randomized clinical trials evaluating this complementary therapeutic approach.