Helicobacter pylori vacA and cagA genotypes in Mexican adults and children

Studies examining associations between Helicobacter pylori virulence marker s and disease have concentrated on adults in developed countries. This stud y assessed adults and children in Mexico. Ninety patients were recruited, 5 6 adults (37 with active peptic ulceration and 19 with no ulcers) and 34 ch ildren (all with recurrent abdominal pain and no ulcers), H. pylori was cul tured from gastric biopsy specimens, and, vacA alleles and cagA were typed by use of polymerase chain reaction from multiple colony sweeps. Multiple v acA types were common in single-biopsy isolates and were more frequent in a dults with ulcers (95%) than in adults without ulcers (37% P < .001) or in children (52%; P < .01). vacA s1b and cagA+ strains were more frequent in a dults than in children. vacA s1 and cagA+ strains had similar frequencies i n adults with and without ulcers, In conclusion, infection with multiple H. pylori strains, defined by different vacA genotypes, is common in Mexico. Such mixed infection is associated with ulcer disease. Strain populations i nfecting Mexican adults and children differ.