There is continuing interest in identifying Helicobacter pylori virulence factors that might predict the risk for symptomatic clinical outcomes. It has been proposed thaticeA and cagA genes are such markers and can identify patients with peptic ulcers. We compared H. pylori isolates from four countries, looking at thecagA and vacA genotypes, iceAalleles, and presentation of the infection. We used PCR to examineiceA, vacA, and cagA status of 424H. pylori isolates obtained from patients with different clinical presentations (peptic ulcer, gastric cancer, and atrophic gastritis). The H. pylori isolates examined included 107 strains from Bogota, Colombia, 70 from Houston, Tex., 135 from Seoul, Korea, and 112 from Kyoto, Japan. The predominant genotype differed among countries: the cagA-positive iceA1 vacA s1c-m1 genotype was predominant in Japan and Korea, thecagA-positive iceA2 vacA s1b-m1 genotype was predominant in the United States, and the cagA-positiveiceA2 vacA s1a-m1 genotype was predominant in Colombia. There was no association between the iceA,vacA, or cagA status and clinical outcome in patients in the countries studied. iceA status shows considerable geographic differences, and neither iceA nor combinations of iceA, vacA, andcagA were helpful in predicting the clinical presentation of an H. pylori infection.

We present a molecular epidemiologic study, based on an analysis of vacA, cagA and cag right end junction genotypes from 1042 Helicobacter pylori isolates, suggesting that H. pylori was present in the New World before Columbus. Eight Native Colombian and Alaskan strains possessed novel vacA and/or cagA gene structures and were more closely related to East Asian than to non-Asian H. pylori. Some Native Alaskan strains appear to have originated in Central Asia and to have arrived after strains found in South America suggesting that H. pylori crossed the Bering Strait from Asia to the New World at different times. ß 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

The prevalence of Helicobacter pylori infection in US adults was shown to be inversely correlated with the socioeconomic status of the family during childhood, and it was suggested that this was additional evidence of transmission occurring in childhood. The present study of H. pylori infection was conducted in South Korea, which has emerged as a developed country in the last two decades. The authors attempted to determine whether there was a difference in prevalence of H. pylori infection in Korean children of different socioeconomic classes despite the high prevalence of infection in childbearing adults. The authors also attempted to identify the factors responsible for the different patterns of transmission by estimating the age-specific prevalence of H. pylori infection in 413 healthy 1- to 75-year-old asymptomatic volunteers who resided in Seoul. H. pylori status was evaluated using an enzyme-linked immunosorbent assay for anti-H. pylori immunoglobulin G. Demographic data were obtained from each individual, and socioeconomic class was assessed by the education level of the adults and of the children's parents as well as family income. H. pylori infection was present in 75% of adults and 22% of children, and its prevalence increased with age (p < 0.001). In adults, the rate of infection was high and independent of socioeconomic class. In children, it was inversely related to the socioeconomic class of the child's family: 12% among upper socioeconomic class, 25% among the middle class, and 41% among the lowest class (p = 0.016). No associations were found between prevalence of H. pylori infection and any factor tested including sex, smoking, and alcohol consumption. In addition, type of housing, whether owned or rented, number of family members living in the same household, water source, and type of community in which a child grew up were not found to be risk factors influencing H. pylori infection prevalence. The prevalence of H. pylori infection in Korea appears to be changing with markedly lower prevalence in children of families of higher socioeconomic status. The factor(s) responsible for the break in the pattern of transmission in children of the higher socioeconomic class was not discovered. Future studies will concentrate on possible differences, eating practices, hygiene, and sanitary practices.

The role and significance of microsatellite instability (MSI) in gastric carcinogenesis remain unknown. This study determined the chronology of MSI in gastric carcinogenesis by examining intestinal metaplasia (IM) from patients with and without gastric cancer. DNA was obtained from gastric specimens of 75 patients with gastric IM (30 cancer, 26 peptic ulcer, and 19 chronic gastritis patients) and was amplified with a set of eight microsatellite markers. Eight (26. 7%) tumors and seven (9.3%) IM samples (three from cancer-free patients) displayed high-level MSI (three or more loci altered). Low-level MSI (one or two loci altered) was detected in 50% of the tumors, in 40% of IM samples coexisting with cancer, and in 38% of IM tissues of cancer-free individuals. Among the 30 cancer patients, microsatellites were more frequently altered in IM coexisting with tumors that showed MSI (P = 0.003). In addition, patients with low-level MSI in the tumor tissues were more likely to have active Helicobacter pylori infection than those with stable tumors (P = 0.02). In conclusion, this study indicates that MSI occurs not only in gastric IM of patients with gastric carcinoma, but also in IM of cancer-free individuals. These data suggest that the progressive accumulation of MSI in areas of IM may contribute to gastric cancer development, representing an important molecular event in the multistep gastric carcinogenesis cascade.

The BabA, cagA, and vacA statuses of 827 Helicobacter pylori isolates were used in logistic regression models to discriminate duodenal ulcer from gastritis. Only BabA was a candidate for a universal virulence factor, but the low c statistic value (0.581) indicates that none of these factors were helpful in predicting the clinical presentation.