vacA genotypes in Helicobacter pylori strains isolated from children with and without duodenal ulcer in Brazil

Data concerning the association between vacA genotypes and disease in child ren in both developed and developing countries are scarce, especially becau se of the small number of children with a duodenal ulcer studied. The vacA genotypes of Helicobacter pylori strains obtained from 65 children (24 with a duodenal ulcer and 41 without a duodenal ulcer; 33 girls; mean age, 10.2 years; age range, 1 to 17 years) were investigated as described by J. C. A therton et al. (J. Clin. Microbiol. 37:2979-2982, 1999). Ten (15.4%) childr en were infected with more than one N. pylori strain. None of these patient s were included in our analysis of the relationship between gastric disorde rs and specific vacA genotypes. The s1 allele was detected in all H. pylori strains isolated from patients with a duodenal ulcer and from 21 (58.3%) p atients without a duodenal ulcer (P = 0.003). Strains with the s2 allele we re found only in patients without ulcer (n = 15; 41.7%). Most s1 strains ha d the s1b allele (97.5%), a result similar to that reported for adults from the Iberian peninsula, which could reflect the Brazilian population origin . One untypeable s1 strain was isolated. The m1 allele was also more freque ntly found in strains obtained from duodenal ulcer patients (P = 0.028). Th e m2 allele was found in strains obtained from 20 (36.4%) children, 3 (15.8 %) with an ulcer and 17 (47.2%) without an ulcer. Only one m hybrid strain (m1 and m2 hybrid) was detected. It was demonstrated for the first time tha t the frequencies of colonization with strains with the s1 allele (14.3% in children up to 8 years of age and 85.7% in older patients; P = 0.012) and of strains with the m1 allele (11.1% in patients up to the age 8 years and 88.9% in older children; P = 0.013) increase with age.