Genotypes of Helicobacter pylori in children with upper abdominal pain

Background: Studies related to genotypes of Helicobacter pylori infection and upper abdominal pain (UAP) in children are scarce all over the world. We prospectively analyzed the association between H. pylori infection and UAP in our study group of children and evaluated the vacA genotypes associated with this disorder. Methods: We investigated 34 children with UAP (group I) and another 110 children as controls without UAP (group II) for H. pylori infection, using antral biopsies by culture, rapid urease tests, histopathology and ureA polymerase chain reaction (PCR). Genotyping was performed using specific cagA and vacA primers on 52 H. pylori strains (group I = 21; 18 boys, mean age 10.33 +/- 2.47 years; group II = 31; boys 21, mean age 9.63 +/- 2.51 years). Results: A significant association between H. pylori infection and UAP was observed when compared to controls (21/34; 61.8%vs 31/110; 28.2%; P = 0.0004). cagA positive H. pylori strains were detected in 20 (95.2%) children with UAP and in 28 (90.3%) controls. Mixed infection was detected in 25% of children with no significant difference between the groups. On univariate regression analysis, s1a, m1 alleles and s1a/m1 genotype of vacA had significant associations with UAP (P = 0.018, 0.015 and 0.007, respectively), while s2 and m2 alleles and the s2/m2 genotype were significantly more frequent in controls (P = 0.034, 0.001 and 0.034, respectively). Conclusions: H. pylori infection is strongly associated with UAP in children and a significantly higher proportion have s1a, m1 alleles and s1a/m1 genotype. The negative associations of vacA s2, m2 alleles and s2/m2 genotype with UAP indicate that they are unlikely to have an important role in this disorder. (C) 2003 Blackwell Publishing Asia Pty Ltd.