Low-cost light-induced therapy to treat rickettsial infection

• Published in: Photodiagnosis and photodynamic therapy 2018-12, Vol.24, p.150-152
• Main Authors: Špitalská, Eva, Špitalský, Zdenko, Markovic, Zoran, Štefanidesová, Katarína, Škultéty, Ľudovít
• Format: Article
• Language: English
• Subjects: Methylene blue; Methylene Blue - pharmacology; Photochemotherapy - methods; Photodynamic therapy; Photosensitizing Agents - pharmacology; Rickettsia; Rickettsia - drug effects
• ISSN: 1572-1000; 1873-1597
• DOI: 10.1016/j.pdpdt.2018.09.018

•The rickettsiacidal effect of methylene blue under red light excitation was proved.•The number of Rickettsia slovaca was reduced due to photodynamic therapy.•Pretreatment had a greater rickettsiacidal impact. Antimicrobial photodynamic therapy uses a nontoxic photosensitizer with the assistance of harmless visible light to activate the photosensitizer. Consequently, the excited state of the photosensitizer interacts with molecular oxygen to produce reactive oxygen species, which have the antimicrobial effect. In this study, we evaluated the effect of photodynamic therapy on Vero cells infected with rickettsia using methylene blue as a photosensitizer along with red light. A significant reduction (by 96%) in the number of viable Rickettsia slovaca was determined by quantitative RT-PCR 48 h after the treatment with methylene blue followed by 30 min of red light excitation. A statistically significant reduction of R. slovaca was also recorded with pretreatment (by 99%). To the best of our knowledge, this result is the first one in the literature to confirm the effectiveness of photodynamic therapy for the elimination of R. slovaca and to suggest this technique as a good supportive treatment for rickettsial infections.