Will a patient who tests positive for H pylori (Helicobacter pylori) with a serum test always test positive thereafter?

From the Guidelines

No, a patient who tests positive for H. pylori with a serum test will not always test positive thereafter. After successful treatment with antibiotics, serum antibody levels gradually decrease, though they may remain detectable for months or even years despite bacterial eradication, as noted in studies such as 1. This is because serum tests detect antibodies to H. pylori, which can persist in the bloodstream long after the infection has been cleared.

Key Considerations for H. pylori Treatment and Follow-Up

• Standard treatment for H. pylori typically involves a combination therapy known as triple therapy: a proton pump inhibitor (such as omeprazole 20mg twice daily) plus two antibiotics (commonly amoxicillin 1g twice daily and clarithromycin 500mg twice daily) for 10-14 days, as discussed in 1.
• Alternative regimens include quadruple therapy or bismuth-based regimens for areas with high clarithromycin resistance.
• To confirm eradication after treatment, non-serological tests are preferred, such as the urea breath test, stool antigen test, or endoscopic biopsy, which should be performed at least 4 weeks after completing antibiotics and while off proton pump inhibitors for 2 weeks, as recommended in 1 and 1.
• These tests directly detect the presence of active bacteria rather than antibodies, making them more reliable for confirming cure.

Importance of Follow-Up Testing

• Follow-up testing is crucial to confirm the eradication of H. pylori, especially in cases of complicated peptic ulcer disease, gastric ulcer, and low-grade gastric MALT lymphoma, as emphasized in 1.
• Non-invasive tests, such as the 13C-UBT, can be used to confirm eradication in uncomplicated peptic ulcer and non-ulcer dyspepsia, but serology should not be used to assess early success or failure of therapy due to the delayed decrease in antibody titers, as noted in 1.

Given the most recent and highest quality evidence from 1, the use of non-serological tests for follow-up is recommended to accurately assess the eradication of H. pylori, ensuring the best outcomes in terms of morbidity, mortality, and quality of life.

From the Research

H pylori Infection and Serum Test Results

• A patient who tests positive for H pylori with a serum test may not always test positive thereafter, as the infection can be eradicated with treatment 2.
• The choice of testing method for H pylori infection depends on several factors, including patient age, presenting symptoms, and medication use, as well as test reliability, availability, and cost 3.
• Serum tests, such as serology with a titre, are suitable for asymptomatic patients, but confirmation of H pylori infection is recommended using a urea breath test if the results prove positive 2.

Eradication of H pylori Infection

• The eradication of H pylori infection is essential to prevent serious complications, including peptic ulcer disease, mucosa-associated lymphoid tissue lymphoma, and gastric cancer 3.
• Triple therapy with a proton pump inhibitor, amoxicillin, and clarithromycin is a common treatment for H pylori eradication, but its efficacy is declining due to rising antibiotic resistance 4, 5.
• Alternative therapies, such as triple therapy with a proton pump inhibitor, amoxicillin, and levofloxacin, have been evaluated, but their efficacy is also limited 5.
• The dose of clarithromycin used in triple therapy can affect the eradication rate of H pylori infection, with higher doses (500 mg b.d.) being more effective than lower doses (250 mg b.d.) 6.

Follow-up Testing

• After treatment, it is essential to test for eradication of H pylori infection using a non-invasive test, such as the urea breath test, to confirm that the infection has been successfully eradicated 2.
• The urea breath test should be performed 4-8 weeks after the end of treatment to avoid false-negative results caused by temporary suppression of the infection 2.
• If the urea breath test is unavailable, a serology with a titre or a biopsy-based test can be used, but these tests may not be suitable for follow-up testing within 6-12 months of eradication therapy 2.