SN2 SHORT NOTE 5M ★ High-yield

Describe the regimens used for Helicobacter pylori eradication and the principles of testing.

Pharmacology · 2nd Professional — Para-Clinical

Rationale

Helicobacter pylori is a gram-negative spiral bacterium colonising the gastric mucosa, present in the great majority of duodenal ulcers and most gastric ulcers, and classed as a class I carcinogen for gastric adenocarcinoma and malt lymphoma.

Eradication cures the ulcer disease, reducing recurrence from about 80% a year to under 5%
Prevalence in India exceeds 60 to 80%, acquired in childhood and related to crowding and sanitation, though only a minority develop disease
It survives in acid by producing urease, which splits urea to ammonia and creates an alkaline microenvironment — the basis of the urea breath test and the rapid urease test

Regimens

Regimen	Composition	Duration and comment
Standard triple therapy	PPI + clarithromycin + amoxicillin (or metronidazole if penicillin allergic), twice daily	14 days. Now failing where clarithromycin resistance exceeds 15%, which includes much of India
Bismuth quadruple therapy	PPI + bismuth subcitrate + metronidazole + tetracycline	14 days. Preferred first-line where clarithromycin resistance is high, and the standard salvage regimen
Concomitant (non-bismuth quadruple)	PPI + clarithromycin + amoxicillin + metronidazole together	14 days; higher eradication than triple therapy
Levofloxacin-based	PPI + levofloxacin + amoxicillin	Salvage therapy; limited in India by high fluoroquinolone resistance
Sequential	PPI + amoxicillin for 5 days, then PPI + clarithromycin + metronidazole for 5 days	Less used now

CLINICAL PEARL

Every eradication regimen contains an acid suppressant, and it is not there for symptom relief. The antibiotics used — particularly amoxicillin and clarithromycin — are unstable and less active at low pH. Raising the intragastric pH makes them chemically stable and lets them work, and also drives the organism into a dividing state in which beta-lactams can act. The proton pump inhibitor is an essential antibacterial adjuvant, not an add-on.

Indications for Testing and Treating

Proven peptic ulcer disease, active or previous
Gastric malt lymphoma — eradication alone induces remission in many early cases, which is remarkable for a lymphoma
Early gastric cancer after resection, and first-degree relatives of gastric cancer patients
Uninvestigated dyspepsia in the young without alarm features — the "test and treat" strategy
Before long-term NSAID or aspirin therapy in patients with an ulcer history
Unexplained iron deficiency anaemia and idiopathic thrombocytopenic purpura

Testing and Confirmation of Cure

Non-invasive tests — urea breath test (the most accurate), stool antigen, and serology (which cannot distinguish current from past infection and is unsuitable for confirming cure)
Invasive tests at endoscopy — rapid urease test, histology, culture with sensitivity testing
Proton pump inhibitors must be stopped 2 weeks before, and antibiotics 4 weeks before, urea breath or stool antigen testing — they suppress the organism and produce false negatives
Confirm eradication at least 4 weeks after finishing treatment, by breath or stool antigen test, in all treated patients

Applied Aspects

Adherence determines success — the regimens involve many tablets and cause nausea, diarrhoea and a metallic taste; explaining that a completed course cures the disease permanently substantially improves completion
Warn about alcohol with metronidazole, and about bismuth blackening the stools and tongue, or the patient will stop in alarm
Take a careful previous antibiotic history — prior macrolide or fluoroquinolone exposure for any reason strongly predicts resistance, and should change the regimen chosen
Clarithromycin-based triple therapy is increasingly inappropriate as first-line in India, given the very high background macrolide and metronidazole use; bismuth quadruple therapy is the more reliable choice
Do not re-use a failed antibiotic in a salvage regimen, with the exception of amoxicillin, to which resistance remains rare
Eradication does not always abolish dyspepsia, since functional dyspepsia is common and coexists; patients should be told this in advance to avoid disappointment and repeated courses

All questions in Gastrointestinal & Respiratory Drugs

Every Pharmacology chapter →