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 (p≤0.026). In the corpus and fundus, fluorescence using 405 nm excitation was greater in H. pylori(+) than in H. pylori(?) subjects only after ALA treatment (p<0.00005, p=0.03). The ratio of 535 nm:405 nm-excited fluorescence decreased from the fundus>corpus>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.