We evaluated two protocols for isolation of Helicobacter pylori in stool from biopsied and nonbiopsied children. Twenty-three child patients whose presumptive positivity or negativity was diagnosed by endoscopy and a rapid urease test at site were used to compare biopsy-based tests with stool-based tests (H. pylori stool antigen test and stool culture). Their gastric activity and bacterial density were graded by the updated Sydney system. Biopsy and stool specimens were cultured on Campy-blood and Belo horizonte agar plates after enrichment in selective Campy-Thio medium. To compare two stool culture protocols, stools from 20 nonbiopsied children were tested by the HpSA test and cultured either as above or after treatment with cholestyramine. Grown colonies were screened by Gram staining, slide agglutination using anti-H. pylori monoclonal IgG; positive isolates were tested by biochemical tests and polymerase chain reaction for H. pylori-specific ureA gene. Coccoid H. pylori was isolated in stool samples from the biopsied patients whose bacterial density was two to four in histology. Their oxidase was slightly positive but became positive after two subcultures, while additional biochemical tests confirmed the isolation of H. pylori. Similar coccoid but oxidase positive H. pylori was isolated from three nonbiopsied children with the protocol of cholestyramine treatment only. The density of bacteria in the stomach may influence the recovery of H. pylori from stool; inactivation of bile with cholestyramine improves the yield in culture and favors isolation of an enhanced metabolic form of bacteria.

Background/aim: More than 50% of Iranian children are infected with Helicobacter pylori; however, no data exist about the association of vacA/cagA genotype/status with disease outcomes in them. We analyzed association of vacA/cagA genotypes/status of children's isolates with gastric inflammation status as the first step in H. pylori pathogenesis. Materials and methods:Antral biopsies for culture and histopathology were taken from 328 children in 1997-2009. vacA (s, m) alleles and cagA statuses of the isolates were determined by PCR. Histopathology was performed according to the Sydney system; gastritis was scored as normal, mild, moderate, severe, and follicular.Results: A total of 159 culture-positive cases, with no mixed infections, were enrolled in the study. Of them, 60% were cagA-positive; 21.4%, 37.1%, 16.3%, and 25.2% cases were s1m1, s1m2, s2m1, and s2m2, respectively. Histopathology showed normal (4.4%), mildchronic (31.4%), moderate-chronic (38.4%), severe-chronic (10.7%), and follicular gastritis (15.1%) cases. Thirty-four (21.4%) of the children had ulcers. Correlation (P < 0.05) was observed between more severe (moderate, severe, follicular) status and both vacAs1 allele and cagA-positive status. No significant relation was observed between genotype/status of vacA/cagA and ulcers (P > 0.05). Conclusion: vacAs1and cagA are associated with more severe gastric inflammation in Iranian children. Association of vacAs1 and cagA with more severe pathology in Iran may be similar to that of other parts of the world.