The reinfection rate of H. pylori reported before ¹³C-urea breath test(¹³C-UBT) era was higher than that of the post ¹³C-UBT era. Children are usually reluctant to receive invasive endoscopic evaluation for the reinfection of H. pylori , particularly when they are asymptomatic. The aim of the study is to discover the reinfection rate by different diagnostic tests, and to find out what causes the difference.

Children confirmed to be eradicated from H. pylori were included in the study. Reinfection was evaluated by endoscopic biopsy based tests(n=34, mean age 11.5±3.7 years) and/or a ¹³C-UBT( n=38, mean age 10.0±3.6 years) at the time of 18 months after eradication. At first visit, H. pylori infection had been diagnosed by positive results from a rapid urease test, Giemsa stain and Warthin-Starry stain and/or a positive culture. Eradication was defined as negative results from all above tests 1-3 months after eradication therapy.

Reinfection rate by endoscopic biopsy based tests was 35.3 percent(12/34). All patients had abdominal symptoms( P =0.000). Reinfection rate was ¹³.2 percent(5/38) by a ¹³C-UBT. Reinfection rate was higher in children with abdominal symptoms( P =0.008). There was no evidence that reinfection rate depended on the sex( P =0.694), age( P =0.827), diseases(peptic ulcers vs gastritis, P =0.730) and eradication regimen( P =0.087).

Helocibacter pylori reinfection rate in Korean children was 13.2 percent per 18 months by a non-invasive test or ¹³C-UBT. Accurate determinations of the reinfection rate in children is affected by the compliance of the diagnostic tests. Non-invasive tests should be considered to investigate the reinfection rate in children.