Helicobacter pylori — diagnosis and eradication

Definition. H. pylori is a Gram-negative, spiral, urease-producing bacterium that colonises the gastric mucus layer. It is a WHO Class I carcinogen.

Why it matters in the elderly. Prevalence rises with age (over 60–70% in Indian elderly). It causes chronic gastritis, peptic ulcer, gastric MALT lymphoma and gastric adenocarcinoma, and worsens NSAID/aspirin ulcer bleeding.

Indications to test ("test and treat"). Active or past peptic ulcer, gastric MALT lymphoma, after resection of early gastric cancer, unexplained iron deficiency anaemia, ITP, long-term NSAID/aspirin or PPI use, and a first-degree relative with gastric cancer.

Alarm features → endoscopy first. New dyspepsia at age ≥60, weight loss, dysphagia, persistent vomiting, anaemia, GI bleeding or abdominal mass. Empirical "test and treat" is not appropriate in the elderly with new dyspepsia.

Non-invasive tests. Urea breath test (13C-UBT) and stool antigen test are the tests of choice for both diagnosis and test-of-cure (sensitivity and specificity >90%). Serology (IgG) cannot distinguish current from past infection and must never be used for test-of-cure.

Invasive (endoscopic) tests. Rapid urease test on antral + body biopsies, histology (Giemsa stain), culture with susceptibility testing, and PCR for clarithromycin resistance.

Causes of false-negative tests. PPI within 2 weeks, antibiotics or bismuth within 4 weeks, active bleeding, and extensive atrophic gastritis/intestinal metaplasia. Stop the PPI two weeks before UBT or stool antigen testing.

First-line eradication (textbook). Standard triple therapy — PPI + clarithromycin 500 mg + amoxicillin 1 g, all twice daily for 14 days. Metronidazole 400 mg BD replaces amoxicillin in penicillin allergy.

Bismuth quadruple therapy. PPI BD + bismuth subcitrate + tetracycline 500 mg QID + metronidazole 400 mg TID for 14 days. Used when clarithromycin resistance is high, after prior macrolide exposure, or after treatment failure. Salvage options are levofloxacin-based or rifabutin-based triple therapy.

Geriatric considerations and confirmation of cure. Check interactions (clarithromycin with statins, digoxin, warfarin and QT-prolonging drugs), adjust amoxicillin/levofloxacin for renal function, warn about C. difficile and use adherence aids. Confirm eradication at least 4 weeks after therapy by UBT or stool antigen — never by serology.

ACG Clinical Guideline 2024 (Am J Gastroenterol 2024;119:1730) — optimized bismuth quadruple therapy for 14 days is now first-line when susceptibility is unknown. Clarithromycin triple therapy and concomitant therapy are no longer recommended empirically because clarithromycin resistance is 22– 32%. Rifabutin triple therapy and vonoprazan-amoxicillin dual therapy are alternatives, and test-of-cure is now mandatory in every treated patient.

Potassium-competitive acid blockers (vonoprazan) — vonoprazan-amoxicillin dual and vonoprazan-clarithromycin-amoxicillin triple regimens are FDA-approved. Vonoprazan dual therapy was superior to lansoprazole-clarithromycin triple therapy in clarithromycin-resistant strains (70% vs 32% eradication), offering a new option for resistant infection.