Serodiagnosis of Helicobacter pylori infection in children by an indirect immunofluorescence test.

The objective of this study was to evaluate the accuracy of an indirect immunofluorescence (IIF) test for serodiagnosis of Helicobacter pylori infection in children and to determine how the test is affected by the presence of antibodies against Campylobacter jejuni. We studied 65 consecutive children (two with endoscopically confirmed duodenal ulcer) and a series of 18 children with duodenal ulcer. Thirty children were H. pylori negative, as determined by culture, by the preformed urease test, and by carbolfuchsin-stained smears. The microorganism was identified by microbiological methods in 35 of the 65 (53.85%) consecutive patients studied and in all children with duodenal ulcer. The titer of the IIF test was > or = 1:20 in the sera of all children with duodenal ulcer and in the sera of 30 of 33 H. pylori-positive children without duodenal ulcer. No H. pylori-negative children had titers > 1:10. A serum dilution of 1:20 discriminated between H. pylori-infected and noninfected children. Absorption with C. jejuni did not change the levels of IgG against H. pylori. When five patients who had been successfully treated with metronidazole, amoxycillin, and furazolidone for 7 days were retested, a slight decrease in anti-H. pylori IgG levels was noted from the third month on. The decrease was more significant 9 months after the eradication of the microorganism.