Why must proton-pump inhibitors be stopped before the test?

PPIs suppress gastric acid and transiently reduce H. pylori bacterial load, which can lower antigen shedding and cause false-negative results. Discontinuing PPIs at least two weeks before testing restores bacterial density and improves test accuracy.

Can the stool antigen test be used to diagnose H. pylori in children?

Yes. Stool antigen testing is validated in paediatric populations and is preferred over serology for diagnosing active infection in children, as it avoids the radiation or isotope exposure of urea breath tests and the invasiveness of endoscopy.

Is this test suitable for screening asymptomatic patients?

Routine screening is not recommended in low-prevalence populations. The test is appropriate for symptomatic patients, those with peptic ulcer disease or a strong family history of gastric cancer, and post-treatment verification, but mass screening is reserved for high-prevalence or high-risk groups per consensus guidelines.

Does a positive result indicate antibiotic resistance?

No. The stool antigen test confirms active infection but does not determine strain virulence factors (CagA, VacA) or antibiotic susceptibility. Resistance testing requires culture or molecular methods, typically from gastric biopsy specimens.

How is the specimen collected?

The patient collects a small stool sample using the collection device in the Genova at-home kit and ships it to the laboratory according to the instructions. The specimen should be collected at least two weeks after stopping PPIs and four weeks after antibiotics or bismuth.

BML-INF-076infectious diseaseUSA

Add-On: Helicobacter pylori EIA

Q: When should the test be performed after eradication therapy?

At least four weeks after completing antibiotics, PPIs, and bismuth. Testing too soon risks detecting residual antigen from dying bacteria or insufficient clearance time, leading to false positives and unnecessary repeat treatment.

Q: What does an equivocal result mean?

An equivocal result falls near the assay's cutoff threshold and cannot reliably confirm or exclude infection. Repeat testing after ensuring adequate time off suppressive medications is advised; if still equivocal, consider urea breath testing or endoscopy with biopsy.

The H. pylori EIA detects bacterial antigen in stool by enzyme immunoassay, diagnosing active gastric Helicobacter pylori infection and confirming eradication post-therapy. It is a validated non-invasive alternative to urea breath testing, suitable for test-and-treat strategies and post-treatment verification when endoscopy is not indicated.

Biomarkers

Stool

Sample

5–7 business days

Turnaround

Fasting

What is the H. pylori EIA test?

The Add-On: Helicobacter pylori EIA detects bacterial antigen in stool by enzyme immunoassay, a validated non-invasive method for diagnosing active gastric H. pylori infection and confirming successful eradication after therapy. Practitioners order this test when investigating dyspepsia, peptic ulcer disease, or atrophic gastritis, and to verify cure at least four weeks after completion of eradication regimens — a step that reduces recurrence and the development of antibiotic resistance. Stool antigen testing offers several advantages over serology: it reflects current infection rather than past exposure, it returns to negative after successful eradication, and it is unaffected by proton-pump inhibitor suppression of bacterial load when sufficient time off therapy is allowed before the test. It is typically ordered as an add-on to comprehensive stool or gastrointestinal panels from the same specialty laboratory, allowing practitioners to assess H. pylori status in the context of broader digestive investigation without requiring a separate specimen.

What does the H. pylori EIA test measure?

H. pylori Ag(Helicobacter pylori Antigen)

Range: NegativeOptimal: NegativeQualitative (Positive/Negative/Equivocal)

Helicobacter pylori is a spiral Gram-negative bacterium that colonises the gastric mucosa, persisting in the acidic environment beneath the mucus layer. Active infection sheds bacterial antigens continuously into the gastrointestinal lumen; these antigens are detectable in stool by enzyme immunoassay. The presence of faecal antigen correlates with active mucosal colonisation, distinguishing current infection from past exposure or inactive disease that might be reflected by serology alone.

Stool antigen testing by EIA is a non-invasive method to diagnose active H. pylori infection and to confirm eradication following treatment. It offers specificity and sensitivity comparable to urea breath testing, without the need for a clinic visit or isotope ingestion, and is the preferred non-invasive method when endoscopy is not indicated. Because the test detects current bacterial shedding rather than antibodies, it is suitable both for initial diagnosis and post-treatment verification.

Why is the H. pylori EIA test ordered?

Diagnostic work-up of uninvestigated dyspepsia in patients under the age threshold for endoscopy (test-and-treat strategy)
Confirmation of active H. pylori infection before initiating eradication therapy, when serology alone cannot distinguish current from past infection
Post-treatment verification of eradication at least four weeks after completion of antibiotic and proton-pump inhibitor therapy
Investigation of recurrent or refractory peptic ulcer disease where H. pylori status is uncertain
Assessment of patients with a family history of gastric cancer or atrophic gastritis, where H. pylori eradication may reduce risk
Evaluation of iron-deficiency anaemia or idiopathic thrombocytopenic purpura when H. pylori is suspected as a contributing factor
As an add-on to comprehensive stool or gastrointestinal health panels to screen for H. pylori in the context of broader digestive symptoms

Sample collection and turnaround

Sample type

Stool

Fasting required

Collection method

At-home collection kit

Turnaround

5–7 business days

Collection notes

Patient collects a small stool sample using the collection device provided in the Genova kit and ships it to the laboratory according to the kit instructions. Discontinue proton-pump inhibitors at least two weeks, and antibiotics or bismuth at least four weeks, before collection to avoid false-negative results. The specimen should be collected before starting any new antimicrobial or antisecretory therapy if the test is for initial diagnosis.

Specimen requirements

Small stool aliquot as specified in the Genova collection kit. Maintain specimen at ambient or refrigerated temperature and return promptly per kit instructions. Avoid contamination with urine or toilet water.

What can affect H. pylori EIA results?

reducesProton-pump inhibitors and antibiotics

PPIs suppress bacterial load transiently, and antibiotics may reduce antigen shedding even if eradication is incomplete; both should be discontinued at least two weeks (PPIs) to four weeks (antibiotics) before testing to avoid false negatives.

reducesBismuth-containing compounds

Bismuth has direct antimicrobial activity against H. pylori and can suppress antigen shedding; discontinue at least four weeks before testing.

variableRecent upper gastrointestinal bleeding

Blood in stool can interfere with some immunoassay formats; correlation with clinical context and repeat testing if equivocal are advised.

reducesLow bacterial density or patchy colonisation

Atrophic gastritis or incomplete colonisation may yield lower antigen concentrations and occasionally equivocal or false-negative results; endoscopic biopsy with histology and culture remains the reference standard in such cases.

variableTiming of post-treatment testing

Testing too soon after eradication therapy (less than four weeks) risks detecting residual antigen from dying bacteria or insufficient time for clearance, leading to false positives; defer testing to at least four weeks post-therapy.

What do H. pylori EIA results mean?

Elevated

Not applicable — this is a qualitative test reporting Positive, Negative, or Equivocal.

Normal

A Negative result indicates that H. pylori antigen was not detected in the stool specimen, consistent with the absence of active gastric infection or successful eradication if the test is performed post-treatment. It does not exclude past infection (which serology might still reflect) or very low-density colonisation below the assay's limit of detection.

Reduced

Not applicable — this is a qualitative test reporting Positive, Negative, or Equivocal.

Note: A Positive result confirms active H. pylori infection and warrants eradication therapy or, if post-treatment, indicates treatment failure and the need for alternative regimens, ideally guided by antimicrobial susceptibility. An Equivocal result should prompt repeat testing after ensuring adequate time off suppressive medications; if repeatedly equivocal or if clinical suspicion is high, consider urea breath testing or endoscopy with biopsy. Ensure the specimen was collected at least two weeks after discontinuing PPIs and four weeks after antibiotics or bismuth to maximise accuracy. The test does not determine bacterial density, strain virulence (CagA, VacA status), or antibiotic resistance — those require molecular or culture methods.

Frequently asked questions

Stool antigen detects current active infection by identifying bacterial proteins shed into the gastrointestinal tract, and it turns negative after successful eradication. Serology detects antibodies that reflect past or present exposure but remain positive for years after treatment, making it unsuitable for confirming cure.

How to access the H. pylori EIA test

The H. pylori EIA reference page is free and open to all practitioners. Create a free practitioner account to see pricing, save tests to your list, and generate requisition forms. Verification takes 1–2 business days.

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About this page

Published: October 7, 2026

Last reviewed: October 7, 2026

References:

Malfertheiner P, et al. Management of Helicobacter pylori infection: the Maastricht VI/Florence consensus report. Gut. (2022)
Chey WD, et al. ACG clinical guideline: treatment of Helicobacter pylori infection. Am J Gastroenterol. (2017)
Gisbert JP, et al. Accuracy of monoclonal stool antigen test for the diagnosis of H. pylori infection: a systematic review and meta-analysis. Am J Gastroenterol. (2006)
Fallone CA, et al. The Toronto consensus for the treatment of Helicobacter pylori infection in adults. Gastroenterology. (2016)

This content is for licensed healthcare practitioners only and does not constitute medical advice. Clinical decisions should be based on the full clinical picture and not on any single test result.