PCR for identification and typing of Helicobacter pylori isolated from children.

From 191 children with upper gastroduodenal disease 236 gastric biopsy specimens were taken. H. pylori was detected by use of culture Gram staining histological examination and PCR technique. A segment of DNA coding protein synthesis of 26 kDa or urease A and B gene were used for PCR amplification. PCR technique was also used for determination of the presence of Cag A gene in 72 strains of H. pylori isolated from children. Genetic typing of H. pylori strains by RFLP analysis of PCR amplified urease B gene 933 bp fragment and RAPD were performed. Biopsy specimens taken from children with gastritis were in 52% H. pylori culture and PCR positive, while 18.1% PCR positive only. Similarly, specimens taken from children with duodenal ulcer were in 50% H. pylori culture and PCR positive, while 12.5% PCR positive only. Fifty one (70.8%) from 72 strains of H. pylori were Cag A positive. Molecular typing of the strains isolated during first and follow-up endoscopy allowed the differentiation between reinfection or new infection and coinfection. It was shown that RAPD typing had better discrimination power in comparison to PCR--RFLP method.