Helicobacter pylori (H. pylori)
Helicobacter pylori is a gram-negative, microaerophilic bacterium that colonizes the human stomach and is the most common infectious disease worldwide, affecting up to 50% of the global population and causing chronic gastritis, peptic ulcer disease, gastric cancer, and MALT lymphoma. 1, 2
Characteristics and Prevalence
- H. pylori is a spiral-shaped bacterium with flagella that allows it to move through and colonize the gastric mucosa
- It survives in the acidic environment of the stomach by producing urease, which neutralizes stomach acid
- Global prevalence varies by region, socioeconomic status, and age, with higher rates in developing countries
- Infection is typically acquired in childhood and persists lifelong if untreated
Clinical Significance and Associated Conditions
Gastrointestinal Conditions
- Chronic gastritis: H. pylori is the most common cause of chronic gastritis 3
- Peptic ulcer disease: Strong association with both gastric and duodenal ulcers 2
- Gastric cancer: Recognized risk factor for gastric adenocarcinoma 2
- MALT lymphoma: First-line treatment for low-grade gastric MALT lymphoma is H. pylori eradication (60-80% cure rate) 2
Extra-gastric Associations
- Iron-deficiency anemia: Strong evidence linking H. pylori to unexplained iron-deficiency anemia 2
- Idiopathic thrombocytopenic purpura (ITP): Evidence supports H. pylori eradication in ITP 2
- Vitamin B12 deficiency: Associated with H. pylori infection 2
- Drug absorption: Can impair absorption of certain medications including thyroxine and l-dopa 2
Pathophysiology
- H. pylori colonizes the gastric mucosa and induces inflammation (gastritis)
- Long-term infection leads to:
- Virulence factors (like CagA and VacA) influence disease severity, though testing for these is not clinically useful 2
Diagnosis
Non-invasive Tests
- 13C-Urea Breath Test: 95% sensitivity and specificity 3
- Stool Antigen Test: 88-90% sensitivity, 91-100% specificity 3
- Serology (ELISA): 90% sensitivity, 95% specificity 3
Invasive Tests (Endoscopy-based)
- Rapid urease test
- Histology
- Culture
- Topographical biopsies from both body and antrum/incisura are essential 3
Treatment
First-line Treatment
- Bismuth quadruple therapy for 14 days is preferred when antibiotic susceptibility is unknown 4
- Triple therapy (amoxicillin, clarithromycin, and PPI) for 14 days has 80-90% cure rate 3
Treatment in Special Populations
- NSAID/Aspirin users: H. pylori eradication is beneficial before starting NSAIDs and mandatory in patients with peptic ulcer history 2
- Long-term PPI users: Eradication prevents progression to atrophic gastritis 2
Post-treatment
- Confirm eradication using non-serological testing at least 4 weeks after treatment 3
- For persistent infection, "optimized" bismuth quadruple therapy or rifabutin triple therapy for 14 days 4
Complications and Surveillance
- Gastric cancer: Higher risk with advanced atrophic gastritis, family history, immigration from high-risk regions, persistent H. pylori infection, and smoking 3
- MALT lymphoma: Regular follow-up after H. pylori treatment; consider alternative treatments if lymphoma persists 2
- Surveillance: Consider endoscopy every 3 years for advanced atrophic gastritis 3
Common Pitfalls in Management
- Overlooking H. pylori infection in patients with gastritis 3
- Missing nutritional deficiencies (iron and vitamin B12) in corpus-predominant gastritis 3
- Failing to consider associated autoimmune conditions in patients with autoimmune gastritis 3
- Inadequate biopsy sampling during endoscopy 3
- Not confirming eradication after treatment
H. pylori represents a significant global health challenge but can be effectively diagnosed and treated with appropriate testing and antibiotic regimens, significantly reducing the risk of serious complications like peptic ulcers and gastric cancer.