title: Helicobacter pylori virulence genotypes in Portuguese children and adults with gastroduodenal pathology.
abstract: The aim of this study was to evaluate the prevalence of virulence genotypes, namely cagA, vacA and babA2, of Helicobacter pylori strains isolated from Portuguese adults and children presenting gastroduodenal pathology. One hundred thirty-six strains were studied, 82 isolated from adult patients (50 with nonulcerative gastritis and 32 with active peptic ulcer) and 58 isolated from children (54 with nonulcerative gastritis and 4 with duodenal ulcer). Genotyping of cagA, vacA and babA2 was assessed by polymerase chain reaction. Overall, Helicobacter pylori strains carrying more virulent genotypes were much more prevalent in adults than in children, particularly the type I ( vacAs1- and cagA-positive) and the triple-positive ( vacAs1-, cagA- and babA2-positive) strains ( P<0.001). A subpopulation of adults and children with nonulcerative gastritis was also studied, and differences in the prevalence of virulent genotypes were observed, either for individual genotypes ( P=0.017 for cagA, P=0.010 for vacAs1) or in combinations, i.e. the type I genotype ( P=0.005) and the triple-positive strains ( P=0.031). There was no difference between the two populations in the distribution of babA2 and m1/m2 genotypes. Considering the cohort effect in the epidemiology of Helicobacter pylori infection, these results suggest that different strains might circulate during different periods of time, or that, after infection in childhood, individual strains will undergo changes during the course of infection.
authors.affiliation: Laboratório de Bacteriologia, Instituto Nacional Saúde Dr Ricardo Jorge, Av Padre Cruz, 1649-016, Lisboa, Portugal. monica.oleastro@insa.min-saude.pt
authors.forename: M
authors.initials: M
authors.lastname: Oleastro
authors.forename: M
authors.initials: M
authors.lastname: Gerhard
authors.forename: A I
authors.initials: AI
authors.lastname: Lopes
authors.forename: P
authors.initials: P
authors.lastname: Ramalho
authors.forename: J
authors.initials: J
authors.lastname: Cabral
authors.forename: A
authors.initials: A
authors.lastname: Sousa Guerreiro
authors.forename: L
authors.initials: L
authors.lastname: Monteiro
mesh_terms: D000328:Adult; D001483:Base Sequence; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004269:DNA, Bacterial / Q000032:analysis; D004381:Duodenal Ulcer / Q000235:genetics / Q000382:microbiology; D005260:Female; D005756:Gastritis / Q000235:genetics / Q000382:microbiology; D005767:Gastrointestinal Diseases / Q000235:genetics* / Q000382:microbiology / Q000473:pathology; D005798:Genes, Bacterial / Q000235:genetics*; D005838:Genotype; D016481:Helicobacter Infections / Q000453:epidemiology / Q000235:genetics*; D016480:Helicobacter pylori / Q000235:genetics* / Q000472:pathogenicity*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011174:Portugal / Q000453:epidemiology; D015995:Prevalence; D011336:Probability; D012307:Risk Factors; D013276:Stomach Ulcer / Q000235:genetics / Q000382:microbiology; D014774:Virulence
chemical_list: D004269:DNA, Bacterial