In H.pylori strains infecting patients, the cagA gene is frequently associated with gastric lesions such as gastroduodenal ulcers. H.pylori prevalence is near 90% in Chilean adults, with antibodies against the CagA product in the majority of them. In this study we determined by PCR the cagA status of H.pylori of children consulting for recurrent abdominal pain, and we correlated this result with the histologic findings in the gastric mucosa. Out of 41 children, 26 (63,4%) were H.pylori-positive by Giemsa staining or urease test, all of them but one with chronic gastritis, active in 14 children. PCR detected 32 (78,1%) children with H.pylori. Half of them (16) were colonized by cagA-positive strains: no specific association with gastric lesions was observed, compared with infected with cagA-negative strains. Antibiotic treatment resulted in bacterial erradication in 69,6% of the colonized children. Four patient in whom H.pylori was not eliminated and who were cagA-positive before treatment were cagA-negative after treatment, suggesting that they were colonized by multiple H.pylori strains, with different patterns of sensitivity to the antibiotics used for erradication.

(Supported in part by Laboratorio Saval, Santiago, Chile).