Fluorescence diagnostics of Helicobacter pylori-infected human gastric mucosa: establishing technique and validity.

OBJECTIVE: Bacterial factors, including strain type, anatomic distribution and density, and host responses are important determinants in the pathogenesis of erosive and neoplastic changes linked to gastric Helicobacter pylori (H. pylori) infection. The purpose of this study was to investigate the potential use of photodiagnostics in mapping H. pylori infection. The relationship between fluorescence in individual gastric pits of H. pylori(+) and H. pylori(-) subjects versus that in larger field views of the gastric mucosa and the use of fluorescence to determine H. pylori status in different gastric areas were studied. MATERIAL AND METHODS: Antrum, corpus and fundus biopsies from 8 H. pylori(+) and 4 H. pylori(-) subjects taken during two gastroscopies were used for autofluorescence (535 nm excitation) and aminolevulinic acid (ALA)-induced protoporphyrin IX fluorescence (405 nm excitation) determinations. RESULTS: In the antrum, corpus and fundus a close correlation between individual pit and full-field image (FFI) fluorescence was demonstrated for H. pylori status (R>0.85; R>0.75; R>0.80) and both excitation wavelengths (R>0.89; R>0.85; R>0.95), respectively. In the antrum, FFI in H. pylori(+) subjects exceeded that in H. pylori(-) subjects using 405 nm but not 535 nm excitation regardless of ALA treatment (pcorpus>antrum for both H. pylori(+) and H. pylori(-) subjects regardless of ALA treatment (p=0.03). CONCLUSIONS: Fluorescence-based identification of areas of H. pylori-infected gastric mucosa using 405 nm excitation combined with ALA treatment is feasible and, using a ratio of 535 nm:405 nm-excited fluorescence, it is possible to distinguish H. pylori status and the different areas of the stomach even without ALA.

Photoeradication of Helicobacter pylori using 5-aminolevulinic acid: preliminary human studies.

BACKGROUND AND OBJECTIVES: Helicobacter pylori (HP) is an endemic pathogenic bacterium causing gastritis and gastroduodenal ulceration in humans and is linked to the development of gastric malignancies. These first human in vivo studies investigated the photoeradication of HP using laser and white light. STUDY DESIGN/MATERIALS AND METHODS: In 13 HP-positive volunteers, a zone of gastric antrum was irradiated with laser (410 nm, 50 J/cm(2)) or endoscopic white light (10 J/cm(2)) 45 minutes after oral 5-aminolevulinic acid (5-ALA) 20 mg/kg. HP-eradication was assessed by biopsy urease test and HP-culture from irradiated and control zones 5 minutes, 4 and 48 hours post-irradiation. RESULTS: A maximum eradication effect was achieved at 4 hours post-irradiation when 85% of biopsies in the monochromatic and 66% in the white light exposed zones, and 58 and 33% in the respective control zones were HP-negative. CONCLUSIONS: HP numbers were greatly reduced following exposure to 5-ALA and either laser or white light in vivo. Photoeradication appears feasible, but further light dosimetry and the development of convenient application methods is required.