Helicobacter pylori antibody profile in household members of children with H. pylori infection

Both family-based Helicobacter pylori infection control and management strategy and screen-and-treat strategy are cost-effective for gastric cancer prevention

BACKGROUND

Helicobacter pylori (H. pylori) infection and its related diseases are substantial public health burden for highly infected areas. Recently, a novel family-based H. pylori infection control and management (FBCM) strategy is introduced for H. pylori infection prevention and control. However, its cost-effectiveness has not been evaluated. We conducted this health economic evaluation to investigate the cost-effectiveness of FBCM, screen-and-treat, and no-screen strategies in Chinese population.

MATERIALS AND METHODS

Cost-effectiveness analysis was performed using decision tree and Markov model. Parameters required for the model were from published literatures and public databases, including health state utility, screening characteristics, treatment effectiveness, and medical costs for the three strategies. Outcomes were cost, quality-adjusted life year (QALY), incremental cost-effectiveness ratio (ICER). Uncertainty analysis was performed to verify the robustness of this model.

RESULTS

To prevent gastric cancer in a cohort of 1 million asymptomatic Chinese families, FBCM and screen-and-treat strategies prevented 1010 and 1201 new gastric cancer cases, reduced 2809 and 3339 gastric cancer-related death, and saved 956,971 and 1,137,549 QALYs, respectively, when compared with no-screen strategy. Cost-effectiveness analysis showed that FBCM strategy cost $9.18/QALY, and screen-and-treat strategy cost $12.08/QALY for gastric cancer prevention when compared with no-screen strategy. One-way sensitivity analysis revealed that screening from younger age by both strategies are more cost-effective. When compared with FBCM strategy, screen-and-treat strategy saved 5.98% gastric cancer cases and 5.78% of gastric cancer deaths, but costed $9348 to reduce a gastric cancer case. Results are not sensitive to any variables, and probabilistic sensitivity analysis confirmed robustness of the results.

CONCLUSIONS

Both FBCM and screen-and-treat strategies are cost-effective for gastric cancer prevention compared with no-screen strategy. Since FBCM is more practical and convenient, it may be an efficient and excellent cost-effective strategy for gastric cancer prevention in H. pylori and gastric cancer prevalent areas.

Household clustering of gastroenteritis

Surveillance for gastroenteritis rarely detects small, intra-familial outbreaks. This study examined intra-household transmission of gastroenteritis using prospectively collected data from 2811 participants (600 households) in a community-based study. There were 258 household clusters of gastroenteritis during the 15 months of observation involving 774 residents (28% of total). Age <6 years and attendance at a day care/kindergarten were associated with increased likelihood of inclusion in a cluster. The reach of illness into the household was extensive, with 63% of household members affected by symptoms during clusters. Simultaneous and secondary transmission of gastroenteritis appeared equally common. In only 20% of clusters did more than one member submit a faecal specimen. Of clusters where two or more specimens were submitted, concordance in laboratory confirmation of pathogens was 18.8%. Our results show that clustering of gastrointestinal symptoms within households occurs commonly, but reliance on pathogen notification data will substantially underestimate the true frequency of gastroenteritis clusters.

Helicobacter pylori infection rate decreases in symptomatic children: a retrospective analysis of 13 years (1993-2005) from a gastroenterology clinic in West Virginia

BACKGROUND

The rate of Helicobacter pylori is decreasing in the developed countries, but few long-term studies are available from the United States. We retrospectively assessed the annual H. pylori infection rate in symptomatic children seen in our clinic over a 13-year study period.

STUDY

A retrospective analysis of all children who had histologic diagnosis of H. pylori infection between January 1993 and December 2005 in our pediatric gastroenterology clinic was performed. The annual infection rate and the overall infection rate were calculated.

RESULTS

A total of 1743 upper endoscopy reports were reviewed, of which 212 (12.1%) were diagnosed with H. pylori infection. A significant decrease in mean annual H. pylori infection rate was noted in the last 6 years of the study period (2000 to 2005), compared with the first 7 years (1993 to 1999) (18.2% vs. 7.3%, respectively; P=0.001).

CONCLUSIONS

The incidence of H. pylori infection in symptomatic children in our clinic is decreasing. A national multicenter study will be needed to assess whether this drop is a local phenomenon or a national trend.

Intra-familial transmission of Helicobacter pylori infection in children of households with multiple generations in Vietnam

This community-based cross-sectional study in 533 participants from 135 households with multiple generations living in the same household aimed at investigating the relationship between Helicobacter pylori infection in children and the other household members. H. pylori infection in children was found significantly associated with the infection in mothers [OR (95% CI): 2.50 (1.19-5.26)], even after being adjusted for sex, age group and sibling number [adjusted OR (95% CI): 2.47 (1.12-5.47)]. It was also significantly associated with the infection in both parents [adjusted OR (95% CI): 4.14 (1.29-13.23)]. No significant association between H. pylori infection in the father, grandparent(s), uncle or aunt with that in their children was found. Results from the present study showed intra-familial transmission in a multi-generation population and supported the hypothesis of person-to-person transmission of H. pylori infection.

Gnotobiotic transgenic mice reveal that transmission of Helicobacter pylori is facilitated by loss of acid-producing parietal cells in donors and recipients

Helicobacter pylori is acquired during childhood, but its mode of transmission remains unclear. A genotyped H. pylori isolate (Hp1) that expresses two classes of adhesins was introduced into the stomachs of three types of germ-free FVB/N mice to model factors that may affect spread of H. pylori in humans. Normal mice represented human hosts with normal gastric acid production. Transgenic animals expressing human alpha-1,3/4-fucosyltransferase in their gastric pit cells represented humans with normal acid production and the commonly encountered Lewis(b) histo-blood group receptor for the bacterium's BabA adhesin. tox176 transgenic mice have a genetically engineered ablation of their acid-producing parietal cells and increased proliferation of gastric epithelial lineage progenitors that express sialylated glycan receptors for the bacterium's SabA adhesin. These mice mimic features encountered in humans with H. pylori-associated chronic atrophic gastritis (CAG). Different combinations and numbers of 6-week-old germ-free normal and transgenic mice were housed together. At least one donor mouse per cage was infected with a single gavage of 10(7) colony-forming units of Hp1. All cagemates were sacrificed 8 weeks later. Cultures of gastric and cecal contents, plus quantitative PCR assays of cecal contents harvested from donors and potential recipients, revealed that transmission only occurred between tox176 donors and tox176 recipients, and that the distribution of Hp1 along the gastrointestinal tract was significantly broader in mice without parietal cells (P < 0.001). Transmission between tox176 mice was not attributable to any significant difference in the density of Hp1 colonization of the stomachs of tox176 versus normal donors. Our findings lead to the testable hypothesis that the relative hypochlorhydria of young children, and conditions that promote reduced acid production in infected adults (e.g. CAG), represent risk factors for spread of H. pylori.

Intrafamilial spread of Helicobacter pylori: a genetic analysis

BACKGROUND

A high incidence of Helicobacter pylori among family members of children with H. pylori gastritis has previously been documented on biopsy material. The main objective of this study was the genetic clarification of H. pylori strains involved in intrafamilial dispersion.

MATERIALS AND METHODS

Formalin-fixed, paraffin-embedded material of antral mucosa from 32 members of 11 families was studied for the presence of genetic homogeneity. To achieve this goal, the entire genome of H. pylori was studied by the polymerase chain reaction (PCR)-based random amplified polymorphic DNA (RAPD) fingerprinting method. Furthermore, the Urease A gene was analyzed using a multiplex PCR-assay and an alternative mutation detection method based on the Hydrolink trade mark analysis.

RESULTS

RAPD fingerprinting confirmed that closely related H. pylori strains were involved in the intrafamilial dispersion. Mutations and small deletions in Urease A gene were found in 22 out of 32 individuals.

CONCLUSIONS

The homology of the H. pylori genome in members of the same family strongly supports the hypothesis of transmission of H. pylori from person-to-person or from a common source.

Helicobacter pylori: resurrection of the cancer link

Helicobacter pylori is one of the most common pathogenic bacterial infections, colonizing an estimated half of all humans. In a subset of individuals, the infection leads to serious gastroduodenal disease such as peptic ulcers and gastric adenocarcinoma. The factors contributing to skewing this, in most cases benign, relationship into disease development are largely unknown. However, factors emanating from the bacterium, host and the environment have been shown to affect the risk for disease, although no factor can be singled out to be most important. The known factors are associated with affecting the risk of disease, and are not absolute. Virulence of H. pylori is affected by the existence and regulation of certain genes present in the bacterial population in a stomach. The effects of H. pylori on gastric cancer development have been challenged and the risk associated with infection with virulent (i.e. Cag PAI positive) H. pylori has likely been underestimated.

Helicobacter pylori infection in Swiss adolescents: prevalence and risk factors

OBJECTIVE

This investigation sought to study the influence exerted by demographic and socioeconomic factors on the prevalence of infection in adolescents living in Switzerland.

DESIGN

Epidemiological study spanning 3 years.

METHODS

We included 196 15- to 16-year-old adolescents from a north-eastern Swiss city in our study, recruited by the school health service during a medical check-up in the years 1999, 2000 and 2001. infection was detected by ELISA using 2nd generation anti- IgG antibodies. Demographic and socioeconomic data were collected by questionnaire.

RESULTS

infection was found in 19 of the 196 (9.7%) tested adolescents. tested positive in, respectively, 13 (7.3%) of the 176 natives and six (30%) of the 20 (P = 0.01 chi-squared) subjects from foreign countries. infection was significantly highly correlated with demographic factors but did not correlate with most of the socioeconomic factors.

CONCLUSION

The rate of infection among Swiss adolescents is one of the lowest in Europe. Nevertheless, an important disparity is evident between the rate of infection observed in the native population and that among immigrants. High living standards available to the majority of the population may explain the minor influence of socioeconomic factors on infection in our country.

Helicobacter pylori infection in Swedish school children: lack of evidence of child-to-child transmission outside the family

BACKGROUND & AIMS

Helicobacter pylori infection is mainly acquired in early childhood, but the exact routes of transmission remain elusive. To distinguish between risks of intrafamilial and extraneous child-to-child transmission, we studied H. pylori seroprevalence among Swedish school children with varying family backgrounds.

METHODS

In a cross-sectional study, 695 of 858 (81%) 10-12-year-olds in 36 school classes in Stockholm donated blood and answered a questionnaire. Infection was detected by enzyme-linked immunosorbent assay and confirmed by immunoblot and urea breath test.

RESULTS

Overall, 112 (16%) children were infected. The seroprevalence was 2% among 435 children with Scandinavian parents and 55% among 144 children with origin in high prevalence areas (Middle East and Africa). Among children born in Scandinavia, the odds ratios (adjusted for gender, socioeconomic status, and family size) for being seropositive were 39.1 (95% confidence interval, 16.7-91.3) and 5.6 (1.8-17.3) when having parents born in high and medium prevalence areas, respectively, relative to children with Scandinavian parents. Importantly, the prevalence of infection among the classmates was not a risk factor for H. pylori infection.

CONCLUSION

Our data indicate that intrafamilial transmission is far more important than child-to-child transmission outside the family. The H. pylori prevalence in the parental generation may be a crucial determinant for the child's risk of contracting the infection.

Helicobacter pylori intrafamilial infections: change in source of infection of a child from father to mother after eradication therapy

Biopsy specimens of the antrum and corpus were obtained from four Helicobacter pylori-infected members of a family and from the same boy (son 1) in whom the infection reappeared after simultaneous successful eradication treatment of three family members, excluding the mother. A total of 18 to 60 H. pylori isolates were obtained from each specimen and subjected to rRNA gene restriction pattern analysis. The father's isolates and the initial isolates from son 1 showed the same HindIII type, which was divided into three HaeIII subtypes. Isolates from the mother and a brother (son 2) and posttreatment isolates from son 1 showed a distinct HindIII type (with one minor subtype), which was divided into six HaeIII subtypes. All subtypes of the initial isolates from son 1 were present in the father's isolates, and all subtypes of the posttreatment isolates from son 1 were present in the mother's isolates but not in son 2's. Electron microscopic analysis of the biopsy specimens demonstrated extremely high levels of H. pylori colonization in the father's gastric mucosa. H. pylori adherence with a ruffle formation was also demonstrated. The findings suggest that son 1 was infected initially with the H. pylori strain of the father and son 2 was infected with the H. pylori strain of the mother and that after eradication therapy son 1 was reinfected with the H. pylori strain of the mother, who did not undergo eradication therapy.

Helicobacter pylori in familial clusters based on antibody profile

Studies have shown a high prevalence of Helicobacter pylori infection in close communities and that intrafamilial spread during early childhood may be a route of transmission. A total of 72 household members from 21 families were enrolled in this study. Sera from individuals showed 50/72 (69.4%) seropositive for IgG against H. pylori by ELISA. Western blots showed diversity in the protein profiles with molecular masses ranging from approximately 8 to 130 kDa. Cohen's kappa statistical analysis of the blot patterns showed that nine families demonstrated similar profiles (100%), while 4 other families showed varying similarities (17-50%). The results support the hypothesis of intrafamilial transmission of H. pylori. Furthermore, serological studies can be used as an effective approach to determine the familial status in relation to H. pylori infection.

High levels of resistance to metronidazole and clarithromycin in Helicobacter pylori strains in children

The aim of the study was to evaluate the prevalence of resistance to amoxicillin, metronidazole, and clarithromycin before treatment of Helicobacter pylori infection in children and to assess the evolution of resistance with time. The study was carried out between 1994 and 1999 with 150 H. pylori-positive children through gastric culture (antimicrobial susceptibility) and histology. All cultured H. pylori strains were sensitive to amoxicillin, 64 (43%) were resistant to metronidazole, 32 (21%) were resistant to clarithromycin, and 14 (9%) were resistant to both metronidazole and clarithromycin. The overall prevalence of resistance to metronidazole and clarithromycin did not change significantly with time. The study highlights the generalized high-level and stable metronidazole and clarithromycin resistance of H. pylori strains from children.

Helicobacter pylori: clonal population structure and restricted transmission within families revealed by molecular typing

Helicobacter pylori infects up to 50% of the human population worldwide. The infection occurs predominantly in childhood and persists for decades or a lifetime. H. pylori is believed to be transmitted from person to person. However, tremendous genetic diversity has been reported for these bacteria. In order to gain insight into the epidemiological basis of this phenomenon, we performed molecular typing of H. pylori isolates from different families. Fifty-nine H. pylori isolates from 27 members of nine families were characterized by using restriction fragment length polymorphism analysis of five PCR-amplified genes, by pulsed-field gel electrophoresis (PFGE) of chromosomal DNA, and by vacA and cagA genotyping. The 16S rRNA gene exhibited little allelic variation, as expected for a unique bacterial species. In contrast, the vacA, flaA, ureAB, and lspA-glmM genes were highly polymorphic, with a mean genetic diversity of 0.83, which exceeds the levels recorded for all other bacterial species. In conjunction with PFGE, 59 H. pylori isolates could be differentiated into 21 clonal types. Each individual harbored only one clone, occasionally with a clonal variant. Identical strains were always found either between siblings or between a mother and her children. Statistical analysis revealed clonality of population structure in all isolates. The results of this study suggest the possible coexistence of a large array of clonal lineages that are evolving in each individual in isolation from one another. Transmission appears to occur primarily from mother to child and perhaps between siblings.

Different Helicobacter pylori strains colonize the antral and duodenal mucosa of duodenal ulcer patients

BACKGROUND

We have investigated the possibility that the same patients may be colonized by Helicobacter pylori strains of different genotypes or phenotypes in the antrum as compared to in the duodenum. The strains were typed for DNA fingerprints, different lipopolysaccharides (LPS), and Lewis antigen expression on the O-side chains of LPS.

MATERIALS AND METHODS

Polymerase chain reaction (PCR) amplifications using primer sequences (i.e., the Enterobacterial Repetitive Intergenic Consensus [ERIC]) and randomly amplified polymorphic DNA (RAPD) elements were performed to asses chromosomal DNA diversity between H. pylori strains. The expression of different LPS types and Lewis antigens in the various H. pylori isolates were determined by whole bacterial enzyme-linked immunosorbent assays using monoclonal antibodies.

RESULTS

Duodenal ulcer patients had different H. pylori genotypes in the duodenum as compared to in the antrum as shown by ERIC-PCR (44%) and by RAPD-PCR (75%). Different DNA patterns were found among the strains that were isolated from various regions of the duodenum in 4 of 16 patients (25%) as shown by ERIC-PCR and in 8 of 16 patients (50%) as shown by RAPD-PCR. Sixty-three percent of the duodenal ulcer patients had H. pylori strains with a different Lewis antigen phenotype in the duodenum as compared to in the antrum, and 3 of 16 patients (19%) had strains with different Lewis antigens expressed by strains from different duodenal biopsies from the same patient.

CONCLUSION

The results suggest that a mixed population of different H. pylori strains with marked variation, both genotypically and phenotypically, colonize the same patient.

Immunoblot analysis of humoral immune response to Helicobacter pylori in children with and without duodenal ulcer

Several studies have demonstrated that enzyme-linked immunosorbent assay is not a sensitive and specific method to diagnose Helicobacter pylori infection in children, especially in the younger ones. Since serum immune response can also be determined by immunoblotting and it permits the detection of antibodies to virulence factors such as CagA and VacA, we evaluated the accuracy of a commercial immunoblotting test to diagnose H. pylori infection and to assess the humoral immune response to different H. pylori antigens in 122 children who underwent upper gastrointestinal endoscopy. The presence of H. pylori was determined in antral biopsy specimens by culture, preformed urease test, and histological analysis. H. pylori was identified by microbiological and histopathological methods in 66 children (including all of the 21 who had duodenal ulcer). Antibodies to H. pylori were detected in 63 infected children and in 8 noninfected ones. The sensitivity, specificity, and positive and negative predictive values of the immunoblotting test were 95.5, 85.7, 88.7, and 94.1%, respectively. The number of immunoreactive bands increased with age (P = 0.003), and the bands of 35 kDa (P = 0.013); 89 kDa, the VacA antigen (P = 0.001); and 116 kDa, the CagA antigen (P = 0.00004) were more frequently observed in older children. The frequency of the bands of 89 kDa (P = 0.001) and 116 kDa (P = 0.03) was higher in children with duodenal ulcer than in H. pylori-positive children without the disease. In conclusion, the immunoblotting test appears to be useful for the diagnosis of H. pylori infection in children, even in the younger ones.