Helicobacter pylori Infection - General Overview
Overview of Gastroenteritis
Overview of Helicobacter pylori Infection
Helicobacter pylori (H. pylori) is a spiral-shaped, gram-negative bacterium that infects the stomach lining. It is associated with gastritis, peptic ulcer disease, gastric adenocarcinoma, and low-grade gastric lymphoma. While many infections are asymptomatic, H. pylori can lead to dyspepsia and more severe complications. Diagnosis is achieved through urea breath tests, stool antigen tests, or biopsy samples during endoscopy. Treatment typically involves proton pump inhibitors (PPIs) combined with antibiotics, often as part of a quadruple therapy regimen.
Epidemiology and Transmission
• Global Prevalence: Common in low- and middle-income countries, with most infections acquired in childhood. In high-income regions, prevalence increases with age, affecting 50% of individuals by age 60.
• High-Risk Groups: More common among Black, Hispanic, and Asian populations, as well as healthcare workers like gastroenterologists due to improper endoscope disinfection.
• Transmission: Likely via oral-oral or fecal-oral routes; bacteria have been cultured from stool, saliva, and dental plaque. Clustering within families and institutions is common.
Pathophysiology
H. pylori thrives in the stomach’s acidic environment by producing ammonia, which neutralizes acid. Its effects vary based on the infection site:
1. Antral-Predominant Infection:
• Increases gastrin production and acid secretion.
• Leads to prepyloric and duodenal ulcers.
2. Body-Predominant Infection:
• Causes gastric atrophy and reduced acid secretion.
• Increases the risk of gastric ulcers and adenocarcinoma.
3. Mixed Infection:
• Affects both antrum and body, resulting in varied clinical effects.
H. pylori infection is strongly associated with gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma, making it a group 1 carcinogen according to the World Health Organization.
Symptoms
Most infections are asymptomatic, but when present, symptoms may include:
• Dyspepsia: Epigastric pain, nausea, and bloating.
• Peptic Ulcers: Burning abdominal pain, especially after meals or at night.
• Gastrointestinal Bleeding: Hematemesis or melena in severe cases.
• Complications: Chronic infections can lead to gastric cancer or MALT lymphoma.
Diagnosis
1. Noninvasive Tests:
• Urea Breath Test: Highly accurate (>95% sensitivity and specificity). Detects labeled CO₂ exhaled after ingestion of urea metabolized by H. pylori.
• Stool Antigen Test: Similar accuracy to urea breath tests, useful for both initial diagnosis and post-treatment confirmation.
2. Invasive Tests:
• Endoscopic Biopsy: Used if endoscopy is performed for other reasons. Biopsy samples are analyzed using rapid urease tests (RUT) or histologic staining.
• Rapid Urease Test: Detects bacterial urease, with >90% sensitivity and specificity.
Noninvasive tests are preferred unless endoscopy is clinically indicated for other purposes, such as evaluating ulcers or cancer.
Treatment
1. First-Line Therapy: Quadruple Therapy
Recommended in regions with clarithromycin resistance rates >15%. This 14-day regimen includes:
• Proton Pump Inhibitor (PPI): e.g., lansoprazole 30 mg twice daily.
• Bismuth Subsalicylate: 524 mg four times daily.
• Metronidazole: 250 mg four times daily.
• Tetracycline: 500 mg four times daily.
2. Triple Therapy
Used in regions with low clarithromycin resistance and no prior macrolide exposure. This 14-day regimen includes:
• PPI: e.g., omeprazole 20 mg twice daily.
• Amoxicillin: 1 g twice daily or metronidazole 250 mg four times daily.
• Clarithromycin: 500 mg twice daily.
3. Alternative Therapies
• Dual Therapy: High-dose PPI with amoxicillin for resistant cases.
• Rifabutin Triple Therapy: For multidrug-resistant strains.
Follow-Up and Confirmation of Eradication
Confirmation of H. pylori eradication is essential, especially in cases of:
• Peptic ulcers.
• Gastrointestinal bleeding.
• MALT lymphoma or gastric cancer.
Post-treatment tests (urea breath test, stool antigen assay, or endoscopy) should be performed ≥4 weeks after therapy. Persistent infection may require sensitivity testing via endoscopy to guide subsequent treatment.
Complications
1. Peptic Ulcer Disease (PUD):
• Chronic infection is a major cause of both gastric and duodenal ulcers.
2. Gastric Cancer:
• H. pylori is linked to intestinal-type adenocarcinoma but not cancer of the gastric cardia.
3. MALT Lymphoma:
• Eradication of H. pylori can lead to complete regression in early-stage MALT lymphoma.
Prevention
While no vaccines are currently available, preventive measures include:
• Ensuring proper hygiene and food preparation.
• Using disinfected medical instruments, particularly endoscopes.
• Promptly treating infections to reduce cancer risk.
Key Takeaways
1. H. pylori is a gram-negative bacterium strongly linked to gastritis, peptic ulcer disease, and gastric cancer.
2. Diagnosis involves noninvasive tests like the urea breath test or stool antigen test, with biopsy-based tests reserved for endoscopy cases.
3. Eradication regimens typically combine PPIs, antibiotics, and bismuth subsalicylate.
4. Confirmation of eradication is crucial to prevent complications like ulcer recurrence or gastric cancer.
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