Helicobacter pylori infection is typically acquired in early childhood, and a predominantly intrafamilial transmission has been postulated. To what extent family members share the same strains is poorly documented. Our aim was to explore patterns of shared strains within families by using molecular typing. Family members of H. pylori-infected 10-to 12-year-old index children identified in a school survey were invited to undergo gastroscopy. Bacterial isolates were typed with random amplified polymorphic DNA and PCRrestriction fragment length polymorphism of the genes ureA-B, glmM, or flaA. The presence or absence of the cag pathogenicity island, a bacterial virulence factor, was determined by PCR. GelCompar II software, supplemented with visual inspection, was used in the cluster analysis. In 39 families, 104 individuals contributed 208 bacterial isolates from the antrum and corpus. A large proportion, 29 of 36 (81%) of the offspring in a sibship, harbored the same strain as at least one sibling. Mother-offspring strain concordance was detected in 10 of 18 (56%) of the families. Of 17 investigated father-offspring relations in eight families, none were strain concordant. Spouses were infected with the same strains in 5 of 23 (22%) of the couples. Different strains in the antrum and corpus were found in 8 of 104 (8%) of the subjects. Our family-based fingerprinting study demonstrates a high proportion of shared strains among siblings. Transmission between spouses seems to be appreciable. The data support mother-child and sib-sib transmission as the primary transmission pathways of H. pylori.Helicobacter pylori colonizes half of the world's population, and the infection is associated with chronic gastritis, peptic ulcer, gastric cancer, and gastric lymphoma. In-depth knowledge of the transmission patterns may constitute important information for future intervention strategies.In the absence of consistent and verified environmental reservoirs, a predominantly person-to-person transmission has been postulated. H. pylori infection is associated with poor living conditions, and possible transmission routes are fecaloral, oral-oral, or gastro-oral, but firm evidence is lacking (36). The infection clusters in families and is usually acquired in early childhood. A child's risk of being infected is largely determined by the presence or absence of infected family members. Having an infected mother has been suggested to be a more prominent risk factor than having an infected father (30,35). Indications of sib-sib transmission have been reported (14). Transmission between spouses occurs but its significance is unclear (5, 9, 19).Molecular typing of pathogens can corroborate and further characterize the transmission pathways suggested by epidemiologic data based on infection status. Shared strains among individuals indicate person-to-person transmission or acquisition from a common source. Unrelated individuals harbor distinct H. pylori isolates (1), while clonal lineages can be discerned within families (2,7,11,16,20,22,24,2...

Helicobacter pylori-associated diseases, such as peptic ulcer and gastric cancer, are common in Vietnam, but the prevalence of the infection is largely unknown. A validated enzyme-linked immunosorbent assay was used for seroepidemiology with 971 samples from the general population, ages 0 to 88 years, with 546 samples from an urban population (Hanoi), and with 425 samples from a poor, rural province (Hatay). The overall seroprevalence of the infection was 746 per 1,000, with a prevalence of 788 per 1,000 in Hanoi and 692 per 1,000 in Hatay (P ‫؍‬ 0.0007). The risk for infection in the rural area of Hatay was 40% lower than in the urban population of Hanoi, with the odds ratio being 0.59 (95% confidence interval, 0.43 to 0.81). The study shows that the prevalence of H. pylori infection is high in Vietnam and especially high in a large urban area, such as the city of Hanoi.Helicobacter pylori infection causes gastritis and peptic ulcer disease and is a cofactor in the development of gastric cancer (16). The prevalence of H. pylori infection is decreasing in developed countries but remains high in many developing countries (11). Data on the epidemiology of H. pylori infection in Vietnam are scarce, but peptic ulcer disease and gastric cancer represent major health problems. In a large survey, conducted at the Hanoi Military Hospital from 1963 to 1983, peptic ulcer was found by endoscopy in 7.8% of 300,000 volunteers, ages 18 to 60 years (19). Official statistics for the year 2001 indicate an age-standardized incidence of 77.26 per 100,000 person-years for gastric and duodenal ulcer disease (4). Gastric cancer is the second-most-common cancer form in men and the third most common in women, with an agestandardized incidence of 23.7 and 10.8 per 100,000 personyears in the year 2000, respectively (12) Seroepidemiological investigations represent the most rapid and convenient way of obtaining a picture of the prevalence of H. pylori infection in a population, but the assays used need to be validated in the population studied (6,10,14). Enzymelinked immunosorbent assay (ELISA) for immunoglobulin G (IgG) detection can be based either on whole-cell sonicate antigen or on one or several purified components of the bacterium as the antigen. A majority of serological studies are now conducted with commercial kits that have been evaluated in developed countries. These commercial kits are often too expensive for developing countries, and use of a validated inhouse ELISA assay based on sonicate antigens would seem preferable.We have previously evaluated with both Swedish and Vietnamese populations an in-house ELISA based on sonicated H. pylori antigen, supplemented with an absorption step with sonicated Campylobacter jejuni antigen to remove cross-reacting antibodies (2, 6, 15, 17). The studies showed that the local strains used for the H. pylori antigen give a better diagnostic performance and also that the cutoff level used for serodiagnosis in the general population needs to be adjusted (6, 17). The aim of the present study wa...

The morphologic conversion of Helicobacter pylori from bacillary to coccoid form was studied by microscopy, viable count on agar plates, and bioluminescence assay of bacterial ATP. When morphologic conversion from bacillary to coccoid form was detected by microscopy, the viable counts and the bacterial ATP decreased. No viable count was found after nine days of incubation, but bacterial ATP was still present. In these cultures in which only the coccoid form of Helicobacter pylori was present, there was no accumulation of extracellular ATP, indicating no leaky cells. During the transition phase from the bacillary to the coccoid form of Helicobacter pylori, the addition of fresh medium increased the intracellular ATP 26-fold. The coccoid form of Helicobacter pylori had a 1000-fold lower ATP level per cell compared to the bacillary form, which indicates a decreased metabolic activity in the coccoid form. Addition of fresh medium to the coccoid cultures from days 9 and 10 increased the ATP level twofold. However, no conversion from coccoid to bacillary form was found in these cultures during prolonged incubation in fresh broth for four weeks. Such conversion needs to be demonstrated before it is proven that the coccoid form of Helicobacter pylori is responsible for transmission and relapse of infection.

Helicobacter pylori infection and peptic ulcer disease are common in developing countries, e.g., Vietnam. An enzyme-linked immunosorbent assay (ELISA) for screening of patients and for seroepidemiology is a useful tool but needs to be validated in the population studied. We used in-house ELISA with sonicated Swedish and Vietnamese strains as antigens to measure immunoglobulin G antibodies after absorption with sonicated Campylobacter jejuni in sera from 270 H. pylori culture-confirmed peptic ulcer patients, 128 Swedish ureabreath test and immunoblot-positive healthy controls, and 432 Vietnamese immunoblot-positive population controls. Sonicated whole-cell antigen based on the local strains showed a significantly better performance. Immunoblot-positive peptic ulcer patients had significantly higher antibody concentrations than immunoblotpositive population controls, necessitating a lower cutoff level if serology is used for screening or epidemiological purposes. The study shows that the parameters of ELISA for H. pylori need to be adjusted for the population being investigated.