[Helicobacter pylori and azithromycin].

Helicobacter pylori is a Gram-negative bacterium with man as the unique reservoir and where the niche is the stomach. Transmission between individuals could be by fecal and oral route. In the stomach, the bacterium is mainly located at the mucus level and adhere to antral cells which are the privileged target. Within the colonized mucosa, H. pylori generates or secretes different deleterious compounds against the epithelial cells: urease, hydrolyzing urea into ammonia, a cytotoxic agent: monochloramine also cytotoxic, various enzymes and a vacuolyzing cytotoxin; all of these also contribute to the pathogenic potential. In addition the associated inflammatory reaction probably plays a part in the lesion process. One important consequence is peptic ulcer disease and particularly duodenal ulcer which can further degenerate into a precancer lesion and to a lesser extent some dyspeptic syndromes. Bacterial eradication can be obtained by the combination of an antisecretory drug with an antibiotic. Macrolides have a good activity against this bacterium. The azithromycin MIC50 is 0.12 mg/l. A bactericidal activity is observed at concentrations equal or higher than 0.10 mg/l. After a single dose of 500 mg, azithromycin concentrations are 0.48 micrograms/g in the mucus and 4 micrograms/g in the gastric tissue. Concentrations persist for a long time, due to long half life (3 days). In pilot clinical trials, with a tritherapy combining azithromycin with metronidazole and omeprazole, 80% of bacterial eradication was obtained. These promising need to be validated by larger clinical trials.