Anti-Helicobacter pylori specific antibody immunohistochemistry improves the diagnostic accuracy of Helicobacter pylori in biopsy specimen from patients treated with triple therapy.Am. J. Gastroenterol

OBJECTIVE: To investigate the effectiveness of immunohistochemical technique to detect Helicobacter pylori (H. pylori) in patients treated with triple therapy. METHODS: Forty patients (18 men, 22 women, mean age 43 years) with active antral gastritis, H. pylori positive at urease test, culture, and histology, were treated for 1 wk with omeprazole, amoxicillin, and metronidazole. Gastritis was scored according to Sydney criteria. Two months after the end of therapy, endoscopy, urease test, culture, and histology were repeated. RESULTS: Culture and histology were negative in 32 (80%) of treated cases. Biopsy specimens of the eradicated group were stained with immunohistochemical technique using an anti-H. pylori specific polyclonal antibody. In 12 of 32 (37.5%) patients, clusters of round or vibrio-shaped bacteria, unidentified at histology, were stained by the specific anti-H. pylori antibody. After triple therapy, at histology all patients were found with improved gastritis. In six patients however, mucosal-associated lymphoid tissue (MALT) appearance, present before therapy, persisted after therapy. In five of six patients with MALT, immunostaining with anti-H. pylori antibody was positive. CONCLUSIONS: The immunohistochemical technique is more accurate than classical methods in identifying H. pylori after specific therapy. This method should, therefore, be used in all studies that aim to achieve eradication. Whether the H. pylori identified at immunohistochemistry is able to reactivate and induce recrudescence of infection remains to be clarified.