Killing Bacteria: Research and Clinical Data

Helicobacter pylori Accumulates Photoactive Porphyrins and Is Killed by Visible Light. Michael R. Hamblin et al., ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, July 2005, p. 2822–2827


Abstract: Helicobacter pylori colonizes the mucus layer of the human stomach and duodenum, causes chronic gastritis, gastric ulcer, and is a risk factor for gastric denocarcinoma.

There is a 20% failure rate in antibiotic therapy, which is increasingly due to antibiotic resistance and necessitates the search for alternative antimicrobial methods. We have discovered that H. pylori when cultured in liquid medium, accumulates significant quantities of coproporphyrin and protoporphyrin IX, both in the cells and secreted into the medium. These photoactive porphyrins lead to cell death (up to 5 logs) by photodynamic action upon illumination with low doses of visible light, with blue/violet light being most efficient. The degree of killing increases with the age of the culture and is greater than that found with Propionibacterium acnes (another bacterium known to be photosensitive due to porphyrin accumulation). Both virulent and drug-resistant strains are killed. The data suggest that phototherapy might be used to treat H. pylori infection in the human stomach.

Low-Light Therapy: Research and Clinical Data


MECHANISMS FOR LOW-LIGHT THERAPY Conference BIOS2006, SPIE, San Jose, CA, January 2006, written by Conference Chairs: Michael R. Hamblin, Harvard Medical School;


Abstract: Low levels of visible light (frequently red or near-infrared) can have significant therapeutic effects on multiple classes of diseases, injuries and medical disorders. In particular it is effective for wound healing and pain control as well as reduction of inflammation and swelling.


It is believed that the primary cellular chromophore that absorbs low levels of red and near-infrared light is cytochrome c oxidase, which is located in mitochondria. This absorption of energy may lead to increase in ATP synthesis and release of reactive oxygen species from the electron transport chain that can subsequently activate transcription factors and lead to cell proliferation and migration.


This conference covers a field that is rapidly achieving a general level of acceptance in the medical and biomedical communities and will cover all of the important areas of LLLT research.


Contributed papers are solicited in the following areas (among others):
   • development of light sources for LLLT
   • study of LLLT dosimetry
   • in vitro research in mammalian cells
   • in vitro research in micro-organisms in culture
   • simulation of wound healing and scar reduction in animal models
   • nerve regeneration
   • prevention of ischemia-induced tissue death and regeneration
   • well-controlled clinical trials in the following areas:
      - stimulation of wound healing such as non-healing ulcers
      - pain reduction in post-surgical and neuralgia patients
      - dental applications
      - dermatology applications
      - reduction of pain and inflammation in arthritis and other orthopedic conditions.
      - reduction of edema.

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