The aims of this study are to investigate the effect of the eradication of H. pylori on histological change of gastric mucosa in children with H. pylori gastritis and to determine whether the histological grading by the Sydney system is valuable in predicting the effect of treatment.

1) Histological scores by the Sydney system and the endoscopic characteristics were assessed before and at least four weeks after anti-H. pylori therapy in 42 children with H. pylori gastritis. 2) In 32 children treated with omeprazole, amoxicillin and clarithromycin (OAC), pretreatment histological scores and endoscopic findings were compared between the eradicated and the noneradicated to evaluate their predictive value for the successful eradication.

1) In the eradicated (27 cases), nodular gastritis significantly decreased from 89% to 63% (p<0.05). There was an significant improvement in the mean activity score from 2.06 before treatment to 0.24 after treatment (p<0.01). The mean inflammatory score also improved from 2.61 before treatment to 1.89 after treatment (p<0.05). Lymphoid follicles significantly decreased from 48% to 15% (p<0.05). Epithelial damage improved in all 4 cases. But in the noneradicated (15 cases), there was no significant change in the frequency of nodular gastritis, the mean activity score, the mean inflammatory score and the frequency of the lymphoid follicles. 2) In 32 children treated with OAC, there was a tendency that the higher was the pretreatment score of the bacterial density, the lower was the eradication rate of H. pylori (p=0.072).

The loss of the polymorphonuclear cell infiltration is the most prominent histological change after successful eradication. There may be negative correlation of the grade of the bacterial density with the success rate of the anti-H. pylori therapy.