What is the recommended diagnostic approach and treatment for an H (Helicobacter) pylori infection?

H. pylori Testing: Diagnostic Approach

Recommended First-Line Testing Strategy

For patients under 50 years without alarm symptoms (bleeding, weight loss, dysphagia, anemia), use non-invasive testing with either the urea breath test (UBT) or laboratory-based monoclonal stool antigen test—these are equally accurate and avoid unnecessary endoscopy. 1, 2

Non-Invasive Testing: The Preferred Approach

Urea Breath Test (UBT)

• Most accurate non-invasive test with sensitivity of 94-97% and specificity of 95-95.7% 1, 2
• Detects active infection only, not past exposure 1
• Requires 6-hour fast before testing 2
• Ideal for both initial diagnosis and post-treatment confirmation 1

Stool Antigen Test

• Comparable accuracy to UBT with sensitivity and specificity of 93.2% 1, 3
• Must use laboratory-based monoclonal antibody tests—rapid in-office immunochromatographic tests have significantly lower accuracy (80-81%) and should be avoided 1, 2
• Detects active infection, not past exposure 1, 3
• More practical and cost-effective than UBT while maintaining equivalent diagnostic performance 1

Serology Testing: Limited Role

Serology should NOT be used for routine diagnosis or confirmation of eradication because it cannot distinguish active infection from past exposure, with overall accuracy averaging only 78% 1, 2

Limited situations where serology may be considered:

• Recent antibiotic or PPI use when medication washout is not possible 1, 2
• Gastric atrophy, gastric malignancies, or active ulcer bleeding where bacterial load may be reduced 1
• Large epidemiologic surveys in high-prevalence populations 4

Invasive Testing: When Endoscopy is Required

Proceed directly to endoscopy with biopsy-based testing in these situations:

Mandatory Endoscopy Indications

• Age ≥50 years with new-onset dyspepsia due to increased malignancy risk 1, 3
• Any patient with alarm symptoms regardless of age: bleeding, weight loss, dysphagia, palpable mass, anemia, malabsorption 1, 3
• Failed eradication therapy requiring culture and antimicrobial sensitivity testing 1
• Regions with high clarithromycin resistance (>15-20%) where susceptibility testing guides treatment 1

Invasive Test Options During Endoscopy

• Histology: Gold standard requiring at least 2 biopsies from antrum and body; immunohistochemistry is most accurate staining method 4, 2
• Rapid urease test (RUT): Sensitivity 80-95%, specificity 95-100%; provides quick results during procedure 2
• Culture: Definitive proof with antimicrobial susceptibility testing; technically demanding but essential after treatment failure 1, 2

Critical Medication Washout Periods

False-negative results are common without proper medication discontinuation:

• Proton pump inhibitors (PPIs): Stop at least 2 weeks before testing (causes 10-40% false-negative rates) 1, 2
• Antibiotics and bismuth: Stop at least 4 weeks before testing 1, 3
• Exception: Serology is the only test unaffected by these medications 1
• Histamine-2 receptor antagonists can substitute for PPIs when acid suppression is needed before testing 1

Post-Treatment Confirmation of Eradication

Test at least 4 weeks after completing eradication therapy using UBT or stool antigen test—never use serology for confirmation. 1, 2, 3

• Serology remains positive for months to years after successful eradication 2
• Post-treatment stool antigen test sensitivity: 92.1%, specificity: 87.6% 1
• Confirmation is strongly recommended for complicated peptic ulcer disease, gastric ulcer, and gastric MALT lymphoma 1

Who Should Be Tested

High-Priority Testing Indications (100% consensus)

• Active or history of peptic ulcer disease 4
• Uninvestigated dyspepsia (under age 50 without alarm symptoms) 4
• Gastric MALT lymphoma 4
• Family history of gastric cancer 4

Additional Testing Indications

• Long-term PPI therapy (>1 year) due to atrophic gastritis risk 1
• Atrophic gastritis or intestinal metaplasia 1
• Family members in same household as infected patients 4
• First-generation immigrants from high-prevalence countries 4

Common Pitfalls to Avoid

• Never use rapid in-office serological tests—limited accuracy and unreliable 1
• Never use serology to confirm eradication—antibodies persist indefinitely 1, 2
• Never test too early post-treatment—wait minimum 4 weeks to avoid false-negatives 1, 2
• Never forget medication washout—PPIs cause up to 40% false-negatives in all tests except serology 1
• Never use panels of IgG, IgA, and IgM tests—no added benefit and often include non-FDA-approved tests 4

Treatment Regimens (When H. pylori Confirmed)

Triple therapy (first-line): Amoxicillin 1 gram + clarithromycin 500 mg + lansoprazole 30 mg, all twice daily for 14 days 5

Dual therapy (clarithromycin allergy/intolerance): Amoxicillin 1 gram + lansoprazole 30 mg, both three times daily for 14 days 5