SAN FRANCISCO — Some diagnostic tests for suspected Helicobacter pylori infection are better validated in adults than in children, John D. Snyder, M.D., reported at a meeting on clinical pediatrics sponsored by the University of California, San Francisco.
Furthermore, most of the diagnostic tests for H. pylori don't distinguish asymptomatic infection from disease. About 80% of people infected with H. pylori have no measurable disease, said Dr. Snyder of UCSF. He discussed the following tests and their applicability to children.
▸ Esophagogastroduodenoscopy. EGD combined with silver-stained biopsies remains the standard for diagnosis. It's the only test that can distinguish asymptomatic infection from disease, and it works as well in children as in adults. But EGD is invasive and relatively expensive.
▸ Commercial serology tests. These tests have about 90% sensitivity and specificity in adults, but they perform significantly worse in children. Published studies of sensitivity and specificity in children have yielded estimates of 63%–78% sensitivity and 84%–88% specificity.
The reasons for this poor performance could be that children have lower antibody titers than adults, antibodies can persist long after an infection is eradicated, maternal antibodies can be transmitted to infants, and immunosuppressant proteins differ in children and adults.
▸ Urea breath test. This test shows some promise. It uses
In adults, sensitivity and specificity have been above 95%. Only limited data are available for children, but those data are encouraging. There's a need for evaluation in larger cohorts of children, especially those under age 3 years.
▸ Stool antigen test. This test is an enzyme-linked immunoadsorbent assay for bacterial protein. It has high sensitivity and specificity in adults and can detect eradication as soon as 2 weeks after therapy. The FDA has approved the stool antigen test as a test of cure in adults.
There have only been two small, single-center trials of this test in children, however.
Dr. Snyder recommended focusing on the history and physical exam in children presenting with abdominal pain. Consider common causes, such as constipation, Giardia, urinary tract infections, and lactose intolerance. Conduct therapeutic trials of a high-fiber diet, a lactose-free diet, or acid suppression.
If none of these therapies resolves the symptoms, consider EGD with biopsy.
First-line treatment recommendations for H. pylori infection are amoxicillin, 50 mg/kg per day in two doses, up to 2 g per day; clarithromycin, 15 mg/kg per day in two doses up to 1 g per day; or a proton pump inhibitor (PPI), 1 mg/kg per day up to 20 mg b.i.d. for 14 days.
The second-line treatment recommendation is amoxicillin plus metronidazole (20 mg/kg per day) plus a PPI for 7–14 days.
And the third-line treatment is clarithromycin plus metronidazole plus a PPI for 7–14 days.