What is the purpose of the Helicobacter pylori (H. pylori) antigen test?

From the Guidelines

The H. pylori stool antigen test is a reliable and preferred method for diagnosing Helicobacter pylori infection, with a high sensitivity and specificity of 93.2% and 93.2%, respectively, as reported in a recent study 1.

Key Points to Consider

• The test detects H. pylori antigens in stool samples, indicating an active infection, and is non-invasive, convenient, and particularly useful for initial diagnosis and confirming eradication after treatment.
• For accurate results, patients should stop taking proton pump inhibitors (like omeprazole) for at least 2 weeks and antibiotics for 4 weeks before testing, as these medications can decrease the bacterial load in the stomach and produce false negative results 1.
• The stool antigen test is preferred over serology because it indicates current infection rather than past exposure, making it valuable for both diagnosis and confirming successful treatment.
• If the test is positive, standard treatment typically involves triple therapy for 10-14 days: a proton pump inhibitor (such as omeprazole 20mg twice daily) plus two antibiotics (commonly amoxicillin 1g twice daily and clarithromycin 500mg twice daily), with quadruple therapy considered in areas with high clarithromycin resistance.

Diagnostic Approach

• The diagnostic strategy should reflect the clinical indication, local availability and costs of tests, and patient preferences, with noninvasive testing generally preferred 1.
• The European Helicobacter Pylori Study Group has recommended the use of either the UBT or stool testing in the initial diagnosis of H. pylori infection, with the stool antigen test being a viable alternative to breath testing after treatment 1.

Test Characteristics

• The polyclonal antibody test has been extensively evaluated in the diagnosis of H. pylori infection before therapy, with a weighted mean sensitivity and specificity of 93.2% and 93.2%, respectively 1.
• The test works by using antibodies to detect H. pylori proteins in stool, reflecting the presence of the bacteria in the stomach, and is susceptible to factors that decrease the bacterial load, such as antibiotics, bismuth, or proton pump inhibitors 1.

From the Research

H.pylori Test Antigen

• The H. pylori stool antigen test, such as the Pylori-Strip® test, is used to evaluate the eradication rate of H. pylori infection after treatment 2.
• This test is used 6 weeks after completing the eradication treatment and with at least 14 days without proton pump inhibitors (PPIs) to confirm the effectiveness of the treatment regimen 2.
• The eradication rate of dual therapy with esomeprazole and amoxicillin was evaluated using the H. pylori stool antigen test, showing an intention-to-treat eradication rate of 91.8% and a per protocol eradication rate of 94% 2.
• Other studies have used different methods to diagnose H. pylori infection, such as urease rapid test, histological analysis, or C13-urea breath test 3, 4.
• However, the H. pylori stool antigen test is a non-invasive and convenient method for diagnosing and monitoring H. pylori infection, making it a useful tool in clinical practice 2.

Treatment Regimens

• Different treatment regimens have been studied for the eradication of H. pylori infection, including triple therapy with a PPI, amoxicillin, and clarithromycin or levofloxacin 3.
• Quadruple therapy with a PPI, amoxicillin, metronidazole, and bismuth subcitrate has also been shown to be effective in eradicating H. pylori infection in children 4.
• The choice of treatment regimen may depend on various factors, including the presence of antibiotic resistance, patient tolerance, and cost-effectiveness 2, 3, 4.

Antibiotic Use

• The use of antibiotics in the treatment of H. pylori infection is crucial, but it also raises concerns about antibiotic resistance and overuse 5, 6.
• Studies have shown that delaying antimicrobial treatment until objective evidence of infection is obtained may not worsen patient mortality and may even be associated with better outcomes and more appropriate use of antimicrobial drugs 5.
• However, the overuse of broad-spectrum antibiotics can lead to potential antibiotic-associated complications, such as new infections or colonization with resistant organisms 6.