Autoimmune metaplastic atrophic gastritis
ICD-10 K29.4 · ICD-11 DA42.0

Treatment of Autoimmune Metaplastic Atrophic Gastritis with Active Helicobacter pylori Infection

This protocol addresses autoimmune gastritis (AIG) presenting alongside an active Helicobacter pylori infection in patients without a true penicillin allergy. Identifying and eradicating H. pylori in this setting is a clinical priority given the compounded risks to gastric health and nutritional status.
Clinical Context

H. pylori testing and treatment are recommended for all patients diagnosed with autoimmune gastritis. Active co-infection carries implications for cancer risk and can worsen nutritional deficiencies — including iron deficiency — that are already a concern in AIG.

For patients without a true penicillin allergy, the full range of evidence-based first-line eradication options is available.

Treatment Approach (First-Line)

A 14-day empiric eradication regimen is indicated. Optimized bismuth quadruple therapy (BQT) is the recommended first-line approach; additional evidence-supported first-line options are available for appropriate patient profiles.

Complete regimen options, selection guidance, and clinical detail are in the full protocol below.

Treatment Goal
✓ Confirmed eradication of H. pylori by a negative test of cure — urea breath test, fecal antigen test, or biopsy-based test — performed no sooner than 4 weeks after completing therapy.
Instant Access to Structured Evidence-Based Regimens
References

DOI: 10.14309/ajg.0000000000002968

Given the implications of potentially undiagnosed H. pylori infection for cancer risk and exacerbating nutritional deficiencies (e.g., iron deficiency), H. pylori testing and treatment in all patients diagnosed with AIG are recommended.

Of the recommended and suggested options for treatment-naive patients, only optimized BQT is suitable for patients with a true penicillin allergy.

In treatment-naive patients with H. pylori infection, optimized BQT is recommended as a first-line treatment option (strong recommendation; moderate quality evidence).

All patients who are treated for H. pylori infection should undergo a test of cure with an appropriately conducted urea breath test, fecal antigen test, or biopsy-based test at least 4 weeks after completion of therapy.

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