Blue-light therapy for H. pylori infection

Helicobacter pylori infection in the stomach causes peptic ulcers and gastric cancer. Antibiotic therapy leads to 80%-eradication but has side effects and increasing antibiotic resistance. We have discovered that H. pylori is susceptible to killing by visible light. Violet light is most effective (six logs10 of kill by 20-J/cm2). We have shown that both the bacterial pellets and culture supernatant accumulate significant amounts of the photoactive porphyrins, coproporphyrin and protoporphyrin. H. pylori is significantly more photosensitive than Propionibacterium acnes, previously thought to be the most sensitive species. Multi-antibiotic resistant strains are also easily killed by light.
A Phase I clinical trial carried out endoscopy with a 1-cm2 site in the pyloric antrum exposed to 405-nm violet light (140-mW/cm2, 40-J). Biopsies were taken from the control and illuminated sites and showed killing of >90% of bacteria (2-tailed p<0.0001). Some patients had bacterial killing approaching 99%. A second clinical trial is underway where patients receive whole stomach illumination at endoscopy with 405-nm light.

 

 

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Hamblin MR, Viveiros J, Yang C, Ahmadi A, Ganz, RA, Tolkoff MJ.  Helicobacter pylori accumulates photoactive porphyrins and is killed by visible light. Antimicrob Agents Chemother,  2005: 49(7): 2822–2827

Ganz, RA. Viveiros J, Ahmad A, Ahmadi A, Khalil A Tolkoff MJ, Nishioka NS, Hamblin MR.  Helicobacter pylori in patients can be killed by visible light. Lasers Surg Med 2005; 36(4): 260-5.