In vitro photodynamic antimicrobial activity of methylene blue and endoscopic white light against Helicobacter pylori 26695

Photodynamic therapy (PDT) is a method for inactivating cells (viral bacterial and cancer cells) using photosensitizers (PS) and light of various wavelengths Helicobacter pylon might be easily affected by light because it has few genes to repair light-induced DNA damage In vitro PDT against H pylon was conducted using endoscopic white light and methylene blue (MB) as the PS before application to in vivo study The bactericidal effects were measured by counting viable cells after PDT The degree of oxidative damage of DNA was confirmed using alkaline gel electrophoresis real-time PCR (RT-PCR) and an assay of 8-hydroxy-2-deoxyguanosine (8-OHdG) In the control group the number of viable cells was maintained constantly during the experiment In the groups treated with either 02 mg/ml MB alone or white light with 002 mg/ml MB for 10 min bacteria decreased approximately a hundredfold The killing effect increased proportionally to the PS concentration and the duration of irradiation DNA damage by PDT proven by alkaline gel electrophoresis RT-PCR and assay of 8-OHdG was greater in PDT-treated groups than in control PDT using MB and endoscopic white light showed effective bactericidal activity in vitro by oxidative DNA damage of H pylon (C) 2010 Elsevier B V All rights reserved