Predominance of mother-to-child transmission of Helicobacter pylori infection detected by random amplified polymorphic DNA fingerprinting analysis in Japanese families.

Helicobacter pylori (H. pylori) is one of the most common bacterial pathogens in humans but the route of transmission remains unclear. We investigated transmission by DNA fingerprinting analysis of cultured H. pylori from pediatric patients and their family members. Forty-two index patients with a mean age of 11.7 years (range, 4-19) were diagnosed as having H. pylori gastritis with or without duodenal/gastric ulcer disease. A total of 66 family members for whom the results of the H. pylori stool antigen test and/or serum H. pylori IgG test were positive underwent endoscopic examination and biopsy or aspiration of gastric juice for H. pylori culture. The extraction of H. pylori genomic DNA and PCR-based RAPD analysis were performed. Thirty-two (76%) of the 42 patients showed DNA fingerprint patterns identical to those of at least one of the respective family members. The patterns of 29 (69%) of the analyses of the H. pylori infected patients were identical to those of their mothers. The patterns for 7 patients were identical to those of their fathers, and those for 6 of the latter patients were also identical to those of their mothers. The rate of fingerprint patterns identical to those of the index patients was significantly higher in those of mothers compared with those of fathers (P < 0.01). Mother-to-child transmission is the predominant route of H. pylori infection in Japan.