A patient with a positive rapid stool antigen test for Helicobacter pylori—should I start standard triple therapy now or first obtain a confirmatory test such as a repeat antigen after stopping proton‑pump inhibitors or a urea breath test?

H. pylori Stool Antigen Test: Proceed with Treatment

A positive H. pylori stool antigen test is reliable and sufficient to initiate triple therapy without confirmatory testing, even if the patient is taking proton pump inhibitors, because PPIs only cause false-negative results—never false-positives. 1, 2

Why You Can Trust This Positive Result

• PPIs cannot create false-positive stool antigen tests. The mechanism of PPI interference works by raising gastric pH and reducing bacterial load, which decreases antigen shedding into stool—this only produces false-negative results in 10–40% of cases. 3, 1, 2

• A positive result during PPI therapy confirms active infection because detectable antigen in stool proves sufficient bacterial load despite acid suppression. 1, 2

• The stool antigen test has excellent diagnostic accuracy with sensitivity of 93.2% and specificity of 93.2% for initial diagnosis when properly performed. 3, 1

Start Triple Therapy Now

Initiate H. pylori eradication immediately based on this positive test. 2

• All H. pylori-infected individuals develop gastritis and face progressive risk for peptic ulcer disease, atrophic gastritis, and gastric cancer—delaying treatment to obtain confirmatory testing provides no clinical benefit and only postpones necessary therapy. 2

• Eradication halts the progression from chronic active gastritis to atrophic gastritis, which is the pathway to gastric adenocarcinoma. 2

Treatment Selection Considerations

• Use high-dose PPI regimens (e.g., omeprazole 40 mg twice daily or equivalent) with 14-day triple therapy or 10–14 day quadruple concomitant therapy for optimal first-line effectiveness exceeding 90%. 4

• In regions with high clarithromycin resistance (>15%), consider bismuth-containing quadruple therapy or perform susceptibility testing if endoscopy is available, because clarithromycin-resistant strains achieve only 10–30% eradication with standard triple therapy. 3

• Standard-dose PPIs are sufficient for 10-day bismuth quadruple therapies (metronidazole-tetracycline-bismuth). 4

Common Pitfall to Avoid

Do not withhold treatment based on suspicion of a false-positive result from PPI use—this represents a fundamental misunderstanding of how PPIs affect H. pylori testing. 2

• If you remain uncertain despite the evidence above, confirm with a urea breath test rather than delaying therapy, though this adds unnecessary cost and time. 2, 5

• The only scenario requiring test confirmation is an unexpected positive urea breath test in patients with known achlorhydria or atrophic gastritis, where non-H. pylori urease-producing organisms may cause false-positives; in that specific case, confirm with stool antigen testing. 2, 5

When Confirmatory Testing Would Be Appropriate

Confirmatory testing is not indicated for your patient with a positive stool antigen test, but would be reasonable in these distinct scenarios:

• A negative stool antigen result in a patient with high clinical suspicion who recently used PPIs—repeat testing after stopping PPIs for 2 weeks. 1, 6

• Antibiotics or bismuth must be stopped for at least 4 weeks before any diagnostic testing to avoid false-negatives. 1, 5