Transient and persistent Helicobacter pylori colonization in Native American children

Immune evasion by proteolytic shedding of natural killer group 2, member D ligands in Helicobacter pylori infection

Background

Helicobacter pylori (H. pylori) uses various strategies that attenuate mucosal immunity to ensure its persistence in the stomach. We recently found evidence that H. pylori might modulate the natural killer group 2, member 2 (NKG2D) system. The NKG2D receptor and its ligands are a major activation system of natural killer and cytotoxic T cells, which are important for mucosal immunity and tumor immunosurveillance. The NKG2D system allows recognition and elimination of infected and transformed cells, however viruses and cancers often subvert its activation. Here we aimed to identify a potential evasion of the NKG2D system in H. pylori infection.

Methods

We analyzed expression of NKG2D system genes in gastric tissues of H. pylori gastritis and gastric cancer patients, and performed cell-culture based infection experiments using H. pylori isogenic mutants and epithelial and NK cell lines.

Results

In biopsies of H. pylori gastritis patients, NKG2D receptor expression was reduced while NKG2D ligands accumulated in the lamina propria, suggesting NKG2D evasion. In vitro, H. pylori induced the transcription and proteolytic shedding of NKG2D ligands in stomach epithelial cells, and these effects were associated with specific H. pylori virulence factors. The H. pylori-driven release of soluble NKG2D ligands reduced the immunogenic visibility of infected cells and attenuated the cytotoxic activity of effector immune cells, specifically the anti-tumor activity of NK cells.

Conclusion

H. pylori manipulates the NKG2D system. This so far unrecognized strategy of immune evasion by H. pylori could potentially facilitate chronic bacterial persistence and might also promote stomach cancer development by allowing transformed cells to escape immune recognition and grow unimpeded to overt malignancy.

Toll-Like Receptor 1 Locus Re-examined in a Genome-Wide Association Study Update on Anti-Helicobacter pylori IgG Titers

BACKGROUND & AIMS

A genome-wide significant association between anti-Helicobacter pylori (H pylori) IgG titers and Toll-like receptor (TLR1/6/10) locus on 4p14 was demonstrated for individuals of European ancestry, but not uniformly replicated. We re-investigated this association in an updated genome-wide association study (GWAS) meta-analysis for populations with low gastric cancer incidence, address potential causes of cohort heterogeneity, and explore functional implications of genetic variation at the TLR1/6/10 locus.

METHODS

The dichotomous GWAS (25% individuals exhibiting highest anti-H pylori IgG titers vs remaining 75%) included discovery and replication sampls of, respectively, n = 15,685 and n = 9676, all of European ancestry. Longitudinal analysis of serologic data was performed on H pylori-eradicated subjects (n = 132) and patients under surveillance for premalignant gastric lesions (n = 107). TLR1/6/10 surface expression, TLR1 mRNA, and cytokine levels were measured in leukocyte subsets of healthy subjects (n = 26) genotyped for TLR1/6/10 variants.

RESULTS

The association of the TLR1/6/10 locus with anti-H pylori IgG titers (rs12233670; β = -0.267 ± SE 0.034; P = 4.42 × 10-15) presented with high heterogeneity and failed replication. Anti-H pylori IgG titers declined within 2-4 years after eradication treatment (P = 0.004), and decreased over time in patients with premalignant gastric lesions (P < 0.001). Variation at the TLR1/6/10 locus affected TLR1-mediated cytokine production and TLR1 surface expression on monocytes (P = 0.016) and neutrophils (P = 0.030), but not mRNA levels.

CONCLUSIONS

The association between anti-H pylori IgG titers and TLR1/6/10 locus was not replicated across cohorts, possibly owing to dependency of anti-H pylori IgG titers on therapy, clearance, and antibody decay. H pylori-mediated immune cell activation is partly mediated via TLR1 signaling, which in turn is affected by genetic variation.

Helicobacter pylori, clinical, laboratory, and noninvasive biomarkers suggestive of gastric damage in healthy school-aged children: A case-control study

BACKGROUND

Helicobacter pylori is acquired largely in early childhood, but its association with symptoms and indirect biomarkers of gastric damage in apparently healthy children remains controversial. We aimed to relate persistent H. pylori infection in apparently healthy school-aged children with clinical, laboratory, and noninvasive biomarkers suggestive of gastric damage using a case-control design.

MATERIALS AND METHODS

We followed up 83 children aged 4-5 years with persistent H. pylori infection determined by stool antigen detection and/or a urea breath test and 80 noninfected matched controls from a low-income to middle-income, periurban city in Chile for at least 3 years. Monitoring included clinical visits every 4 months and annual assessment by a pediatric gastroenterologist. A blood sample was obtained to determine laboratory parameters potentially associated with gastric damage (hemogram and serum iron and ferritin levels), biomarkers of inflammation (cytokines, pepsinogens I and II, and tissue inhibitor metalloproteinase 1), and expression of cancer-related genes KLK1, BTG3, and SLC5A8.

RESULTS

Persistently infected children had higher frequency of epigastric pain on physical examination (40% versus 16%; P = 0.001), especially from 8 to 10 years of age. No differences in anthropometric measurements or iron-deficiency parameters were found. Persistent infection was associated with higher levels of pepsinogen II (median 12.7 ng/mL versus 9.0 ng/mL; P < 0.001); no difference was observed in other biomarkers or gene expression profiles.

CONCLUSIONS

H. pylori infection in apparently asymptomatic school-aged children is associated with an increase in clinical symptoms and in the level of one significant biomarker, pepsinogen II, suggesting early gastric involvement.

Transient and Persistent Gastric Microbiome: Adherence of Bacteria in Gastric Cancer and Dyspeptic Patient Biopsies after Washing

Helicobacter pylori is a common colonizer of the human stomach, and long-term colonization has been related to development of atrophic gastritis, peptic ulcers and gastric cancer. The increased gastric pH caused by H. pylori colonization, treatment with antibiotics or proton pump inhibitors (PPI) may allow growth of other bacteria. Previous studies have detected non-Helicobacter bacteria in stomach biopsies, but no conclusion has been made of whether these represent a transient contamination or a persistent microbiota. The aim of this study was to evaluate the transient and persistent bacterial communities of gastric biopsies. The washed or unwashed gastric biopsies were investigated by cultivation and microbiota analysis (16S rRNA gene-targeted amplicon sequencing) for the distribution of H. pylori and other non-Helicobacter bacteria. The number of cultured non-Helicobacter bacteria decreased in the washed biopsies, suggesting that they might be a transient contamination. No significant differences in the bacterial diversity were observed in the microbiome analysis between unwashed and washed biopsies. However, the bacterial diversity in biopsies shown H. pylori-positive and H. pylori-negative were significantly different, implying that H. pylori is the major modulator of the gastric microbiome. Further large-scale studies are required to investigate the transient and persistent gastric microbiota.

Gastric Damage and Cancer-Associated Biomarkers in Helicobacter pylori-Infected Children

Helicobacter pylori (H. pylori) is well-known to be involved in gastric carcinogenesis, associated with deregulation of cell proliferation and epigenetic changes in cancer-related genes. H. pylori infection is largely acquired during childhood, persisting long-term in about half of infected individuals, a subset of whom will go on to develop peptic ulcer disease and eventually gastric cancer, however, the sequence of events leading to disease is not completely understood. Knowledge on carcinogenesis and gastric damage-related biomarkers is abundant in adult populations, but scarce in children. We performed an extensive literature review focusing on gastric cancer related biomarkers identified in adult populations, which have been detected in children infected with H. pylori. Biomarkers were related to expression levels (RNA or protein) and/or methylation levels (DNA) in gastric tissue or blood of infected children as compared to non-infected controls. In this review, we identified 37 biomarkers of which 24 are over expressed, three are under expressed, and ten genes are significantly hypermethylated in H. pylori-infected children compared to healthy controls in at least 1 study. Only four of these biomarkers (pepsinogen I, pepsinogen II, gastrin, and SLC5A8) have been studied in asymptomatically infected children. Importantly, 13 of these biomarkers (β-catenin, C-MYC, GATA-4, DAPK1, CXCL13, DC-SIGN, TIMP3, EGFR, GRIN2B, PIM2, SLC5A8, CDH1, and VCAM-1.) are consistently deregulated in infected children and in adults with gastric cancer. Future studies should be designed to determine the clinical significance of these changes in infection-associated biomarkers in children and their persistence over time. The effect of eradication therapy over these biomarkers in children if proven significant, could lead to modifications in treatment guidelines for younger populations, and eventually promote the development of preventive strategies, such as vaccination, in the near future.

Magnitude of Helicobacter pylori and associated risk factors among symptomatic patients attending at Jasmin internal medicine and pediatrics specialized private clinic in Addis Ababa city, Ethiopia

BACKGROUND

More than 50% of the people are infected worldwide with H. pylori which causes significant public health morbidity and mortality. The distribution is quite different from country to country. Hence, early information is very important to prevent upper gastrointestinal complications. The current study aimed to assess the magnitude of H. pylori and associated risk factors among symptomatic patients attending at Jasmin internal medicine and pediatrics specialized private clinic from August 2017 until May 2018 in Addis Ababa city, Ethiopia.

METHODS

A cross-sectional study was conducted among 487 patients with upper gastrointestinal tract complaints attending at Jasmin internal medicine and pediatrics specialized private clinic from August 2017 until May 2018. Convenient sampling technique was used to enroll participants. Information regarding to risk factors was assessed using structured questionnaire. Stool samples were collected for H. pylori antigen test. Data was entered and analyzed using SPSS version20 statistical software and a p-value less than 0.05 was considered as statistically significant.

RESULTS

The overall prevalence of H. pylori among participants using stool antigen was 36.8% (n = 179/487). Regarding to family income status, those who have low monthly income were more likely to be infected with H. pylori infection (AOR = 6.056, CI 95% = 1.603-22.881, P = 0.037). In addition, families with low educational level were more likely to be infected with H. pylori infection than higher level education (AOR = 4.150, CI95% = 1.059-16.270, P = 0.041). Number of family members in the house-hold, type of toilet they used and source of drinking water were not significantly associated with H. pylori infection.

CONCLUSIONS

The prevalence of H. pylori infection was 36.8% and it was related to low income and low education levels. This finding calls for improving the socioeconomic status of the community. Moreover, further studies are needed to investigate potential risk factors for H. pylori infection.

An association of Helicobacter pylori infection with endoscopic and histological findings in the Nepalese population

Background:

Helicobacter pylori (H. pylori) is one of the most common human infections worldwide particularly in the developing countries. We aimed to study an association of H. Pylori infection with endoscopic and histological findings in the Nepalese population.

Materials and Methods:

We conducted a study between Oct 2014 and Jan 2015 after meeting inclusion and exclusion criteria. Institutional Review Board approval was obtained from National Academy of Medical Sciences. Endoscopic findings and histopathological diagnosis were documented and data were analysed.

Results:

A total of 113 patients who had complete endoscopy were enrolled. The prevalence of H. pylori infections recorded was 27 (23.9%) patients. There were 17 (62%) male and 10 (37%) female infected with H. pylori (P = 0.33). All biopsied specimens were sent to pathology lab for examination. The most common endoscopic findings was erythematous antral gastritis (40.7%) followed by erosive gastritis 34 (30.1%), pangastritis 10 (8.8%), duodenal ulcer 13 (11.5%), gastric ulcer 9 (8%), erosive fundal gastritis 2 (1.8%), reflux esophagitis 10 (37%) (P < 0.04). Histology revealed that 23 (85.2%) patients had chronic active gastritis (CAG); (P < 0.001).

Conclusions:

Our study revealed that H. pylori infection is strongly associated with chronic active gastritis (CAG) and Reflux esophagitis in Nepalese adults.

High prevalence and low spontaneous eradication rate of Helicobacter pylori infection among schoolchildren aged 7-12 years

AIM

Helicobacter pylori infections mainly occur during childhood and may cause chronic diseases and persist for life unless they are treated. The aim of this study was to identify the prevalence and infection status of H. pylori infection among schoolchildren.

METHODS

We conducted a cross-sectional study of 867 children (52% male) aged 7-12 years in a primary school in the Minhang District of Shanghai, China, in 2014, and a one-year follow-up study of 352 subjects. The 13C-urea breath test was used to identify the H. pylori infection at baseline and one year later. A parental questionnaire provided information regarding the children's socioeconomic status and household environment.

RESULTS

The overall prevalence of the H. pylori infection was 24.1% (209/867), with a 95% confidence interval of 21.3% to 27.0%. The one-year follow-up study of 352 subjects found that 33.5% were positive for the infection at baseline and 66.5% were negative. We found that 27.1% of the positive cases recovered and 8.9% of the negative cases acquired the infection during the year. The spontaneous eradication rate was only 2.9% over the one-year period.

CONCLUSION

The prevalence of the H. pylori infection among Chinese schoolchildren aged 7-12 was high and spontaneous eradication was low.

When is Helicobacter pylori acquired in populations in developing countries? A birth-cohort study in Bangladeshi children

Helicobacter pylori colonization is prevalent throughout the world, and is predominantly acquired during childhood. In developing countries, >70% of adult populations are colonized with H. pylori and >50% of children become colonized before the age of 10 years. However, the exact timing of acquisition is unknown. We assessed detection of H. pylori acquisition among a birth cohort of 105 children in Mirzapur, Bangladesh. Blood samples collected at time 0 (cord blood), and at 6, 12, 18, and 24 months of life were examined for the presence of IgG and IgA antibodies to whole cell H. pylori antigen and for IgG antibodies to the CagA antigen using specific ELISAs and immunoblotting. Breast milk samples were analyzed for H. pylori-specific IgA antibodies. Cord blood was used to establish maternal colonization status. H. pylori seroprevalence in the mothers was 92.8%. At the end of the two-year follow-up period, 50 (47.6%) of the 105 children were positive for H. pylori in more than one assay. Among the colonized children, CagA prevalence was 78.0%. A total of 58 children seroconverted: 50 children showed persistent colonization and 8 (7.6%) children showed transient seroconversion, but immunoblot analysis suggested that the transient seroconversion observed by ELISA may represent falsely positive results. Acquisition of H. pylori was not influenced by the mother H. pylori status in serum or breastmilk. In this population with high H. pylori prevalence, we confirmed that H. pylori in developing countries is detectable mainly after the first year of life.

Gastric Helicobacter pylori Infection Affects Local and Distant Microbial Populations and Host Responses

Helicobacter pylori is a late-in-life human pathogen with potential early-life benefits. Although H. pylori is disappearing from the human population, little is known about the influence of H. pylori on the host's microbiota and immunity. Studying the interactions of H. pylori with murine hosts over 6 months, we found stable colonization accompanied by gastric histologic and antibody responses. Analysis of gastric and pulmonary tissues revealed increased expression of multiple immune response genes, conserved across mice and over time in the stomach and more transiently in the lungs. Moreover, H. pylori infection led to significantly different population structures in both the gastric and intestinal microbiota. These studies indicate that H. pylori influences the microbiota and host immune responses not only locally in the stomach, but distantly as well, affecting important target organs.

Persistent and transient Helicobacter pylori infections in early childhood

BACKGROUND

Helicobacter pylori, the main cause of peptic ulcer disease and gastric cancer in adult populations, is generally acquired during the first years of life. Infection can be persistent or transient and bacterial and host factors determining persistence are largely unknown and may prove relevant for future disease.

METHODS

Two cohorts of healthy Chilean infants (313 total) were evaluated every 3 months for 18-57 months to determine pathogen- and host-factors associated with persistent and transient infection.

RESULTS

One-third had at least one positive stool ELISA by age 3, with 20% overall persistence. Persistent infections were acquired at an earlier age, associated with more household members, decreased duration of breastfeeding, and nonsecretor status compared to transient infections. The cagA positive strains were more common in persistent stools, and nearly 60% of fully characterized persistent stool samples amplified cagA/vacAs1m1. Persistent children were more likely to elicit a serologic immune response, and both infection groups had differential gene expression profiles, including genes associated with cancer suppression when compared to healthy controls.

CONCLUSIONS

These results indicate that persistent H. pylori infections acquired early in life are associated with specific host and/or strain profiles possibly associated with future disease occurrence.

Present and past Helicobacter pylori infection in Mexican school children

BACKGROUND

In developing countries, more than 50% of children have serological evidence of Helicobacter pylori infection. However, serological tests for H. pylori did not differentiate between active and past infection. The objectives of this study were to estimate the frequency of active and past H. pylori infection utilizing functional urea breath test (UBT) and serological tests and evaluate factors associated with the infection.

METHODS

A total of 675 school children, 6-13 years of age, participated. UBT was performed to detect active H. pylori infection. Blood samples were obtained to determine iron status and Immunoglobulin G (IgG) responses to the H. pylori whole-cell and to Cag A antigens by antigen-specific enzyme-linked immunosorbent assays. Weight, height, and sociodemographic characteristics were recorded.

RESULTS

A total of 37.9% (95% Confidence Intervals (CI): 34.2-41.6) of school children had active or past H. pylori infection; of them, 73.8% (CI95% 68.4-79.2) were carrying CagA-positive strain, 26.5% (CI95% 23.2-29.8) had active infection, and 11.4% (95%CI: 9.0-13.8) had evidence of past H. pylori infection. School children with iron deficiency and low height for age had higher risk of H. pylori infection: [OR to active or past infection was 2.30 (CI 95% 1.01-5.23) and to active infection it was 2.64 (CI 95% 1.09-6.44)] compared to school children with normal iron status and height for age or with normal iron status but low height for age or with iron deficiency and normal height for age.

CONCLUSIONS

The estimated prevalence of infection depends of the test utilized. Frequency of H. pylori infection and carrying CagA-positive strains was high in this population. Malnutrition was associated with active H. pylori infection.

Probiotics for the treatment of Helicobacter pylori infection in children

The combination of a proton pump inhibitor and two antibiotics (clarithromycin plus amoxicillin or metronidazole) has been the recommended first-line therapy since the first guidelines for Helicobacter pylori (H. pylori) infection in children were published. In recent years, the success of eradication therapies has declined, in part due to the development of H. pylori resistant strains. Alternative anti-H. pylori treatments are currently becoming more popular than the traditional eradication methods. Components that may be used either as a monotherapy or, in combination with antimicrobials, resulting in a more effective anti-H. pylori therapy have been investigated in depth by several researchers. One of the potential therapies is probiotic cultures; promising results have been observed in initial studies with numerous probiotic strains. Nevertheless, many questions remain unanswered. In this article, we comprehensively review the possible mechanisms of action of probiotics on H. pylori infection, and present the results of published studies using probiotics as possible agents to control H. pylori infection in children. The effect of the addition of probiotics to the standard H. pylori eradication therapy for the prevention of antibiotic associated side-effects is also discussed.

Diagnosis of Helicobacter pylori infection by invasive and noninvasive tests

Although several invasive and noninvasive tests have been developed for the diagnosis of Helicobacter pylori infection, all of the tests have their limitations. We conducted a study to investigate and compare the suitability of rapid urease test (RUT), serology, histopathology and stool antigen tests with polymerase chain reaction (PCR) for detection of H. pylori, and correlate the diagnostic methods with PCR. Eighty nine patients (61 adults, 28 children) referred to the Firoozgar Hospital and Children Medical Center Hospital for diagnostic upper gastrointestinal endoscopy entered to the study and noninvasive tests such as immunoassay for serological antibodies against H. pylori and detection of its antigen in feces were measured. The biopsies were utilized for histological examination, RUT and PCR. The H. pylori statuses were evaluated by the positivity of ureC PCR in biopsy specimens and 53 subjects had H. pylori positive result. Histopathology showed high overall performance in adults and children with sensitivity and specificity 100% and 90%, respectively. Sensitivity, specificity, and accuracy for stool antigen test were 87.8%, 75% and 82%, respectively. Correlation of RUT, serology (IgG), histopathology and stool antigen tests with PCR were 0.82, 0.32, 0.91 and 0.63, respectively. In conclusion, the RUT and histopathology are as accurate as the PCR of biopsy and stool antigen test can consider as appropriate noninvasive test for detection of H. pylori infection.

The potential of dextran-based glycoconjugates for development of Helicobacter pylori vaccine

We have recently demonstrated that synthetic glycoconjugates based on delipidated lipopolysaccharide (LPS) of Helicobacter pylori and containing an α(1-6)-glucan chain induced broadly cross-reactive functional antibodies in immunized animals. To investigate the candidacy of α(1-6)-glucan as an alternative vaccine strategy we prepared glycoconjugates based on dextrans produced by lactic acid bacteria Leuconostoc mesenteroides B512F and consisting of linear α(1-6)-glucan chains with limited branching. Three dextrans with averaged molecular masses of 5,000 Da, 3,500 Da and 1,500 Da, respectively, were modified with a diamino group-containing linker and conjugated to a carrier protein, tetanus toxoid (TT) or diphtheria toxoid (DT), and their immunological properties investigated. The conjugates were immunogenic in both rabbits and mice and induced specific IgG responses against α(1-6)-glucan-expressing H. pylori LPS. Studies performed with post-immune sera of mice and rabbits immunized with dextran-based conjugates demonstrated cross-reactivity with LPS from typeable and non-typeable strains of H. pylori and selected mutants. The post-immune sera from rabbits that received the conjugates exhibited functional activity against α(1-6)-glucan-positive strains of H. pylori. These data provide evidence that dextran-based conjugates may offer a simplified approach to the development of carbohydrate-based vaccines against H. pylori.

Helicobacter pylori colonization critically depends on postprandial gastric conditions

The risk of Helicobacter pylori infection is highest in childhood, but the colonization process of the stomach mucosa is poorly understood. We used anesthetized Mongolian gerbils to study the initial stages of H. pylori colonization. Prandial and postprandial gastric conditions characteristic of humans of different ages were simulated. The fraction of bacteria that reached the deep mucus layer varied strongly with the modelled postprandial conditions. Colonization success was weak with fast gastric reacidification typical of adults. The efficiency of deep mucus entry was also low with a slow pH decrease as seen in pH profiles simulating the situation in babies. Initial colonization was most efficient under conditions simulating the postprandial reacidification and pepsin activation profiles in young children. In conclusion, initial H. pylori colonization depends on age-related gastric physiology, providing evidence from an in vivo infection model that suggests an explanation why the bacterium is predominantly acquired in early childhood.

Natural history of Helicobacter pylori infection in Mexican schoolchildren: incidence and spontaneous clearance

OBJECTIVES

The aim of the present study was to estimate the incidence and spontaneous clearance rate of Helicobacter pylori infection and the effect of some variables on these outcomes in schoolchildren.

METHODS

From May 2005 to December 2010, 718 schoolchildren enrolled in 3 public boarding schools in Mexico City participated in the follow-up. At the beginning of the study and every 6 months thereafter, breath samples were taken to detect H pylori infection; blood samples and anthropometric measurements were taken to evaluate nutritional status. Data on sociodemographic characteristics were collected.

RESULTS

The prevalence of H pylori infection was 38%. The incidence rate was 6.36%/year. Schoolchildren with anemia or iron deficiency at the beginning of the study (who received iron supplements) showed a higher infection acquisition rate than those with normal iron nutritional status, hazard ratio (HR) 12.52 (95% confidence interval [CI] 4.01%-39.12%), P < 0.001 and HR 2.05 (95% CI 1.09%-3.87%), P = 0.027, respectively. The spontaneous clearance rate of the infection was 4.74%/year. The spontaneous clearance rate was higher in children who had iron deficiency (who received iron supplements), HR 5.02 (95% CI 1.33%-18.99%), P = 0.017, compared with those with normal nutritional iron status. It was lower in schoolchildren with ≥ 2 siblings compared with schoolchildren with 1 or no siblings, HR 0.23 (95% CI 0.08%-0.63%), P = 0.004.

CONCLUSIONS

H pylori infection status is dynamic in schoolchildren. Variables related to health status and infection transmission, such as iron status and number of siblings, are important for the incidence and spontaneous clearance of H pylori infection.

Apparent incidence of Helicobacter pylori in adulthood: to what extent do new infections reflect misclassification?

BACKGROUND

Helicobacter pylori infection is a key risk factor for a variety of gastrointestinal diseases. About half of the world population is infected. Most infections are acquired early in childhood, but the occurrence of new infections among adults has also been suggested.

METHODS

We review epidemiological studies providing estimates of incidence of H. pylori infection among adults and evaluate to what extent incidence estimates might have been affected by measurement error of infection status.

RESULTS

Thirty-two studies could be included in the review. Annual incidence was lower than 1.0 % in 17 studies; no correlation between length of follow-up and cumulative incidence was observed. Apparent cumulative incidences of the magnitudes observed in most studies would be expected, because of less than perfect sensitivity and specificity of the diagnostic tests, even in the absence of any true new infections. CONCLUSION/IMPACT: Apparent incidence rates of H. pylori infection among adults in Western populations should be interpreted with utmost caution.

Longitudinal analysis of serological responses of adults to Helicobacter pylori antigens

Because Helicobacter pylori persist for decades in the human stomach, the aim of this study was to examine the long-term course of H. pylori-specific serum immunoglobulin G (IgG) responses with respect to subclass and antigenic target. We studied paired serum samples obtained in 1973 and in 1994 in Vammala, Finland, from 64 healthy H. pylori-positive adults and from other healthy control subjects. H. pylori serum immunoglobulin A, IgG, and IgG subclass responses were determined by antigen-specific enzyme-linked immunosorbent assays. H. pylori-specific IgG1 and IgG4 subtype responses from 47 subjects were similar in 1973 and 1994, but not when compared with unrelated persons. H. pylori-specific IgG1:IgG4 ratios among the participants varied >1000-fold; however, 57 (89.1%) of 64 subjects had an IgG1:IgG4 ratio >1.0, consistent with a predominant IgG1 (Th1) response. Furthermore, ratios in individual hosts were stable over the 21-year period (r = 0.56; P < .001). The immune response to heat shock protein HspA was unchanged in 49 (77%) of the 64 subjects tested; of the 15 whose serostatus changed, all seroconverted and were significantly younger than those whose status did not change. These findings indicate that H. pylori-specific antibody responses are host-specific with IgG1:IgG4 ratios stable over 21 years, IgG1 responses predominating, and HspA seroconversion with aging.

Exposure to Helicobacter pylori-positive siblings and persistence of Helicobacter pylori infection in early childhood

OBJECTIVES

Cross-sectional studies suggest that Helicobacter pylori may be transmitted between siblings. The present study aimed to estimate the effect of an H pylori-infected sibling on the establishment of a persistent H pylori infection.

MATERIALS AND METHODS

The authors used data collected from a Texas-Mexico border population from 1998 to 2005 (the "Pasitos Cohort Study"). Starting at age 6 months, H pylori and factors thought to be associated with H pylori were ascertained every 6 months for participants and their younger siblings. Hazard ratios were estimated from proportional hazards regression models with household-dependent modeling.

RESULTS

Persistent H pylori infection in older siblings always preceded persistent infection in younger siblings. After controlling for mother's H pylori status, breast-feeding, antibiotic use, and socioeconomic factors, a strong effect was estimated for persistent H pylori infection in an older sibling on persistent infection in a younger sibling (hazard ratio 7.6, 95% confidence interval 1.6-37], especially when the difference in the age of the siblings was less than or equal to 3 years (hazard ratio 16, 95% confidence interval 2.5-112).

CONCLUSIONS

These results suggest that when siblings are close in age, the older sibling may be an important source of H pylori transmission for younger siblings.

Presence of Helicobacter pylori in a sibling is associated with a long-term increased risk of H. pylori infection in Israeli Arab children

BACKGROUND AND OBJECTIVES

We examined the dynamics of Helicobacter pylori infection between pre-school and school ages and compared the determinants of late acquisition of H. pylori infection with determinants of early and persistent H. pylori infection.

METHODS

ELISA was used to detect H. pylori antigens in stool specimens collected from children at preschool age (3-5 years) and from their mothers and siblings in 2004. The children were tested again for H. pylori at school age (6-9 years) in 2007-2009. Household and socioeconomic characteristics were obtained by interviews.

RESULTS

The prevalence of H. pylori infection increased from 49.7% (95% CI 42.8, 56.7) in 2004 to 58.9% (95% CI 51.8, 65.6) in 2007-2009. Among children tested in both examinations, 69 (49.3%) had persistent infection, 14 (10.0%) were new cases, 56 (40.0%) remained uninfected, and one (0.7%) had lost H. pylori infection. The approximate annual incidence of infection during 2004-2009 was 5%. Sibling's H. pylori positivity at baseline increased the risk for late acquisition of H. pylori infection; adjusted prevalence ratio (PR) 4.62 (95% CI 0.76, 28.23) (p = .09), while maternal education lowered the risk; adjusted PR 0.84 (95% CI 0.69, 1.01) (p = .06). Sibling's H. pylori positivity was the only significant variable associated with early and persistent H. pylori infection in multivariate analysis.

CONCLUSIONS

Most H. pylori infections are acquired at preschool age and transient infection beyond this age is uncommon in this population. Helicobacter pylori-infected siblings are the major reservoir of H. pylori in early and late childhood demonstrating sustained intra-familial transmission of H. pylori.

Repeat-associated plasticity in the Helicobacter pylori RD gene family

The bacterium Helicobacter pylori is remarkable for its ability to persist in the human stomach for decades without provoking sterilizing immunity. Since repetitive DNA can facilitate adaptive genomic flexibility via increased recombination, insertion, and deletion, we searched the genomes of two H. pylori strains for nucleotide repeats. We discovered a family of genes with extensive repetitive DNA that we have termed the H. pylori RD gene family. Each gene of this family is composed of a conserved 3' region, a variable mid-region encoding 7 and 11 amino acid repeats, and a 5' region containing one of two possible alleles. Analysis of five complete genome sequences and PCR genotyping of 42 H. pylori strains revealed extensive variation between strains in the number, location, and arrangement of RD genes. Furthermore, examination of multiple strains isolated from a single subject's stomach revealed intrahost variation in repeat number and composition. Despite prior evidence that the protein products of this gene family are expressed at the bacterial cell surface, enzyme-linked immunosorbent assay and immunoblot studies revealed no consistent seroreactivity to a recombinant RD protein by H. pylori-positive hosts. The pattern of repeats uncovered in the RD gene family appears to reflect slipped-strand mispairing or domain duplication, allowing for redundancy and subsequent diversity in genotype and phenotype. This novel family of hypervariable genes with conserved, repetitive, and allelic domains may represent an important locus for understanding H. pylori persistence in its natural host.

Detection of cytotoxin genotypes of Helicobacter pylori in stomach, saliva and dental plaque

BACKGROUND

The aim of this study was to detect the presence of Helicobacter pylori and its virulent cagA genes in the oral cavity of individuals with upper gastric diseases. Sixty-two individuals (42+/-2.3 years) with dispepsy symptoms, referred for gastroscopy and who were H. pylori positive in the gastric biopsy, were recruited and separated in two groups: case group-individuals with gastric disease (n = 30); control group-individuals with no gastric disease (n = 32); saliva, dental plaque and biopsy samples were collected from all individuals. Oral and biopsy samples were analyzed by PCR using specific primers for H. pylori 16S ribosomal and cagA genes. PCR products were sequenced for DNA homology confirmation. H. pylori was detected neither in dental plaque nor in saliva in the control group. In the case group H. pylori DNA was detected in 16/30 (53.3%) saliva samples and in 11/30 (36.6%) dental plaque samples. The cagA gene was detected in 13/30 (43.3%) gastric biopsies, in 7/16 (43.8%) saliva samples, and in 3/11 (27.3%) dental plaque samples. Eighteen (60.0%) individuals in the case group were H. pylori positive both in oral and biopsy samples, and 8 (26.6%) of those were positive for cagA-H. pylori DNA. H. pylori and its virulent clone showed a higher prevalence in the oral cavity of individuals in the case group than in the control group (p < 0.05). Our results suggest that dental plaque and saliva may serve as temporary reservoir for H. pylori and its virulent cagA variant in individuals with gastric disease.

Infection by Helicobacter pylori in Bangladeshi children from birth to two years: relation to blood group, nutritional status, and seasonality

BACKGROUND

A birth cohort of 238 children was followed in an urban slum in Dhaka, Bangladesh, to determine incidence, prevalence, and epidemiologic factors related to Helicobacter pylori infection.

METHODS

H. pylori infection was determined by a specific stool antigen test as well as enzyme-linked immunosorbent assay for detecting specific IgA and IgG antibodies in sera in children who completed 2 years of follow-up.

RESULTS

Using the stool antigen test and serology, 50% and 60% of infants respectively, were positive for H. pylori by 2 years; an increase in the infection rate was seen after 6 months of age. Determination of specific antibodies in sera and detection of H. pylori antigen in stool were comparable. A typical seasonality, peaking in spring and autumn, was observed for acquisition of initial H. pylori infection. Children with blood group "A" were more susceptible to H. pylori infection than those with other ABO blood groups. Malnutrition did not seem to promote colonization by H. pylori. However, H. pylori-infected children were more often infected by multiple enteropathogens, often isolated at different time points.

CONCLUSIONS

This study shows that noninvasive diagnostic methods such as serology and the stool antigen test are suitable for the study of acquisition of H. pylori infections in infants and can be used in field settings as well as in laboratories and clinical setting having less well equipped facilities. The study also shows seasonality for initial H. pylori infection and a relationship between blood group "A" and infection.

Acquisition of Helicobacter pylori infection in early childhood: independent contributions of infected mothers, fathers, and siblings

OBJECTIVES

Infected siblings, mothers, and fathers have all been suggested to be major sources for Helicobacter pylori acquisition among children, but few studies have addressed the potential role of various family members simultaneously.

METHODS

A systematic review was performed on studies investigating intrafamilial transmission of childhood H. pylori infection. Within the Ulm Birth Cohort Study, which consists of 1,066 healthy newborns, born between November 2000 and November 2001 and followed up to age 4, and their siblings and parents, the independent role of the infection status of parents and siblings in transmission of H. pylori among children at age 4 was assessed.

RESULTS

Among four studies reporting infected mothers and siblings as independent risk factors for childhood H. pylori infection, odds ratios (ORs) for childhood infection given an infected sibling decreased meaningfully after adjustment for maternal infection status. Within the Ulm Birth Cohort Study, the prevalence of infection was 3.0% among index children at age 4. In bivariate analyses, maternal, paternal, and sibling infection were all strongly and significantly related to infection of the child. However, after multivariate adjustment, only maternal infection persisted as the single strong and significant risk factor (OR 13.0, 95% confidence interval 3.0-55.2).

CONCLUSIONS

These patterns suggest that mutual control for H. pylori status of other family members is crucial for estimating the role of mothers, fathers, and siblings in the transmission of childhood H. pylori infection. In populations with low H. pylori prevalence the infected mother is likely to be the main source for childhood H. pylori infection.

Antibody-based detection tests for the diagnosis of Helicobacter pylori infection in children: a meta-analysis

Background

Numerous serologic tests are available for the diagnosis of H. pylori infection in children. Common designs of antibody-based detection tests are ELISA and Western Blot (WB). For developing countries with limited laboratory resources and access, ELISA would be the preferred method because of its simplicity, lower cost and speed. Although in adults ELISA has proven to be highly accurate in diagnosing H. pylori infection; in children, it has shown variable accuracy.

Methods/Findings

We conducted a systematic review and meta-analysis to assess the accuracy of antibody-based detection tests for the diagnosis of H. pylori infection in children. Selection criteria included participation of at least 30 children and the use of a gold standard for H. pylori diagnosis. In a comprehensive search we identified 68 studies. Subgroup analyses were carried out by technique, immunoglobulin class, and source of test (commercial and in-house). The results demonstrated: 1) WB tests showed high overall performance, sensitivity 91.3% (95% CI, 88.9–93.3), specificity 89% (95% CI, 85.7–91.9), LR+ 8.2 (95% CI, 5.1–13.3), LR− 0.06 (95% CI, 0.02–0.16), DOR 158.8 (95% CI, 57.8–435.8); 2) ELISA-IgG assays showed low sensitivity 79.2% (95% CI, 77.3–81.0) and high specificity (92.4%, 95% CI, 91.6–93.3); 3) ELISA commercial tests varied widely in performance (test for heterogeneity p<0.0001); and 4) In-house ELISA with whole-cell antigen tests showed the highest overall performance: sensitivity 94% (95% CI, 90.2–96.7), specificity 96.4% (95% CI, 94.2–97.9), LR+ 19.9 (95% CI, 7.9–49.8), LR− 0.08 (95% CI, 0.04–0.15) DOR 292.8 (95% CI, 101.8–841.7).

Conclusions/Significance

WB test and in-house ELISA with whole-cell antigen tests are the most reliable tests for the diagnosis of H. pylori infection in children. Antigens obtained from local strains of the community could partially explain the good overall accuracy of the in-house ELISA. Because of its cost and technical demands, in-house ELISA might be more suitable for use in developing countries.

Correspondence between Helicobacter pylori antibodies and urea breath test results in a US-Mexico birth cohort

The uncertain accuracy of methods for detecting Helicobacter pylori infection in young children complicates research on this infection in early life. The aim of the present report was to describe the correspondence between positive serology and positive urea breath test (UBT) in children followed from age 0 to 24 months in the Pasitos Cohort Study, conducted along the US-Mexico border at El Paso and Juarez. Children were recruited before birth during 1998-2000 and examined at target ages of 6, 12, 18 and 24 months. H. pylori infection was detected using an enzyme immunoassay for serum immunoglobulin G antibodies and the (13)C-urea breath test corrected for age-dependent variation in CO(2) production. Of 472 children, 125 had one or more positive UBT results and 46 had one or more positive serology results. The prevalence of H. pylori infection at target ages of 6, 12, 18 and 24 months was 7%, 14%, 16% and 19%, respectively, by UBT and 8%, 2%, 3% and 3%, respectively, by serology. Few (<1%) of those tested on both tests were positive on both at any age. Among UBT-positive children, 6% were concurrently seropositive and 6% became seropositive later. Because UBT positivity cut points were selected to minimise false positives, these results suggest that H. pylori infection occurred frequently in this cohort, but rarely produced detectable antibodies. For clinical or epidemiological investigations, serology should not be used as the sole method for detecting H. pylori infection in children aged 2 years or less.

[Helicobacter pylori infection in children]

Knowledge about Helicobacter pylori infection in children continues to advance. While its prevalence appears to be falling in developed countries, it remains a major problem in developing nations. Its transmission pathway remains highly controversial. It has not yet been definitively elucidated, although the oral-oral route seems most probable. Infection is most often intrafamilial. Risk factors for infection are associated with low socioeconomic level, including overcrowding, unhygienic conditions, sharing beds in childhood, low maternal educational level. Infection in children differs from that in adults in three respects: symptoms, endoscopic appearance of the gastric mucosa, and histologic appearance of lesions. No study has established a clear association between recurrent abdominal pain and H. pylori infection. Nonetheless, in proven infections, recurrent abdominal pain is the most common marker. More recently, an association has been reported between H. pylori infection and iron deficiency anemia. The endoscopic aspect most suggestive of H. pylori infection in children is micronodular gastritis, but it is not specific to H. pylori infection. In children as in adults, H. pylori infection is always associated with histologic gastritis. Many questions about H. pylori remain unanswered, and numerous studies are still needed.

Helicobacter pylori colonization in the first 3 years of life in Japanese children

BACKGROUND

Acquisition of Helicobacter pylori infection occurs in early childhood, but the exact time of the acquisition and dynamics of infection are not clear. The aim of this study was to estimate the time of acquisition of H. pylori colonization in infants.

SUBJECTS AND METHODS

This prospective follow-up study included 237 infants born in Wakayama Rosai Hospital from February, 2001 to April, 2002. Stool samples were collected at indicated ages, and H. pylori antigens were determined by a stool antigen test, HpSA.

RESULTS

One-hundred and eight infants among initially enrolled 237 children have been followed up until 24 months. Among these, 16 infants turned to be HpSA positive within 12 months, but only four remained positive by the consecutive tests with optical density values of more than 0.7. They were assumed persistent positives. The rest 12 infants reverted to be negative by the consecutive tests and were assumed transient or false-positives. The optical density values of HpSA in the transient cases were exclusively less than 0.35.

CONCLUSIONS

The consecutive follow up of HpSA, but not the one-point test, might be useful to diagnose persistent colonization of H. pylori in young infants, and some infants seemed to acquire H. pylori infection in the first year of life. These results should be taken into account for prevention and treatment strategies for H. pylori infection in infants.

Specific serum immunoglobulin G to H pylori and CagA in healthy children and adults (south-east of Iran)

AIM: To evaluate the serologic IgG response to H pylori and CagA across age groups and in healthy children and adults.

METHODS: Totally, 386 children aged 1-15 years and 200 adults aged 20-60 years, were enrolled to study. The serum samples of participant were tested for presence of anti-H pylori and anti-CagA IgG by using ELISA method.

RESULTS: The seroprevalence of H pylori in adults was significantly higher than that observed in children (67.5% vs 46.6%; P < 0.000003). In children, the seropositivity rate in males (51.9%) was significantly (P < 0.05) higher than that observed in females (41.7%). The prevalence of serum anti-CagA antibody was 72.8% and 67.4% in infected children and adults, respectively. The mean titer of serum anti-CagA antibodies was significantly higher among children in comparison to adults (64.1 Uarb/mL vs 30.7; P < 0.03). In infected children and adults the prevalence of serum anti-CagA antibody was higher in males compared to females (78.4% vs 66.3%; P = 0.07 and 75.6% vs 54.71%; P < 0.04, respectively). The age-specific prevalence of anti-H pylori and anti-CagA antibody (in infected subjects) was 37.6% and 59.57% at age 1-5 years, 46.9% and 75% at age 6-10 years, 54.9% and 79.45% at age 11-15, 59.01% and 83.33% at age 20-30 years, 66.6% and 60.52% at age 31-40 years, 73.46% and 63.88% at age 41-50 years and 75.75% and 60% at age 51-60 years with mean titer of anti-CagA antibody of 75.94, 63.32, 57.11, 52.06, 23.62, 21.52 and 21.80 Uarb/mL, respectively. There was significant difference between mean serum anti-CagA antibody in age subgroups (P < 0.001).

CONCLUSION: These results showed that anti-H pylori and anti-CagA antibodies were common in the children and adults. The H pylori-specific antibodies influenced by age and sex of subjects. Moreover, it seems that males are more susceptible to infection with CagA⁺ strains compared to females. The seroprevalence of anti-CagA antibody was increased with age, up to 30 years and then decreased. It was also found that the magnitude of the IgG response to CagA decreased with advanced age.

Gastroenteritis and transmission of Helicobacter pylori infection in households

The mode of transmission of Helicobacter pylori infection is poorly characterized. In northern California, 2,752 household members were tested for H. pylori infection in serum or stool at a baseline visit and 3 months later. Among 1,752 person considered uninfected at baseline, 30 new infections (7 definite, 7 probable, and 16 possible) occurred, for an annual incidence of 7% overall and 21% in children <2 years of age. Exposure to an infected household member with gastroenteritis was associated with a 4.8-fold (95% confidence interval [CI] 1.4-17.1) increased risk for definite or probable new infection, with vomiting a greater risk factor (adjusted odds ratio [AOR] 6.3, CI 1.6-24.5) than diarrhea only (AOR 3.0, p = 0.65). Of probable or definite new infections, 75% were attributable to exposure to an infected person with gastroenteritis. Exposure to an H. pylori-infected person with gastroenteritis, particularly vomiting, markedly increased risk for new infection.

The mother as source of Helicobacter pylori infection

BACKGROUND

To further elucidate the intrafamilial transmission of Helicobacter pylori infection, we investigated the occurrence of infection by parental infection status in a large community-based birth cohort of children from Germany.

METHODS

Parental infection (at birth) and children's infection (at age 3 years) were determined by C-urea breath test and by monoclonal antigen stool test.

RESULTS

Twenty of 834 children (2.4%) were found to be infected. The odds ratio for H. pylori infection of the child was 12.9 (95% confidence interval = 3.2-52.5) if the mother was infected and 1.4 (0.4-4.6) if the father was infected, after adjustment for infection status of the other parent and for nationality. The number of older siblings was not a risk factor for H. pylori infection of the child.

CONCLUSIONS

This longitudinal study suggests that infected mothers are the main source of H. pylori infection of their children.

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Pathogenesis of Helicobacter pylori infection

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori.

Problem of distinguishing false-positive tests from acute or transient Helicobacter pylori infections

BACKGROUND

Reliable detection of acute Helicobacter pylori infections remains problematic. The high prevalence of false-positive non-invasive tests in low H. pylori prevalence populations makes identification of acute and transient infections difficult.

METHODS

We explored the use of serum pepsinogens (PG) for diagnosis of acute infection in patients following H. pylori challenge such that the onset of the infection was known. We then compared those findings to a group of children with presumed acute infections defined as a positive urea breath test (UBT) and negative IgG serology.

RESULTS

We examined the pattern and calculated cut-off values of PG levels in 18 adult volunteers with known acute H. pylori infection. We then compared the results with sera from nine symptomatic children with presumed acute H. pylori infection and a matched control group of nine children who did not meet criteria for acute H. pylori infection. In acute infection, both PGI and II levels increased following H. pylori infection reaching a peak by 2 weeks post-infection. The frequency of a positive test defined as a value > mean +2 SD was 17, 71, and 94% at week 1, 2, and 4 post-infection, respectively. Only one child with presumed acute H. pylori infection had an elevated serum PGI and one had an elevated PGII. Five of the children had follow-up UBTs and four were negative consistent with the diagnosis of false-positive UBT. H. pylori infection was confirmed in the child with an elevated PGI level.

CONCLUSIONS

These data suggest that a single positive noninvasive test in populations of low prevalence is most likely a false-positive result. This suggests that a single positive test requires confirmation preferably using a test that measures a different parameter (e.g., UBT confirmed by stool antigen test). It appears that most "transient"H. pylori infections are diagnosed on the basis of false-positive tests. PG levels are possible candidates as the confirmatory test.

Age-specific incidence of Helicobacter pylori

BACKGROUND & AIMS

Helicobacter pylori is most likely acquired in childhood, but the incidence of infection has not been determined prospectively by using an appropriate noninvasive test. The aim of this study was to determine the age-specific incidence of Helicobacter pylori infection in children and the risk factors for infection.

METHODS

Three hundred twenty-seven healthy index children between 24 and 48 months of age were enrolled over 15 months. At baseline, the Helicobacter pylori infection status of each index child and his or her older siblings and parents was assessed by using the carbon 13-urea breath test. All noninfected index children were then followed up with an annual carbon 13-urea breath test for 4 years to determine whether they became infected with Helicobacter pylori and, if so, the age at first infection. Information on potential risk factors was collected at baseline and each subsequent visit.

RESULTS

At baseline assessment, 28 of 327 (8.6%) index children were infected with Helicobacter pylori. The mean age of the 28 infected children was 32.78 months (SD, 5.14 months). Over the next 4 years, 279 index children not infected at baseline contributed 970 person-years of follow-up to the study. During this time, 20 children became infected with Helicobacter pylori. The rate of infection per 100 person-years of follow-up was highest in the 2-3-year age group (5.05 per 100 person-years of follow-up (95% confidence interval, 1.64-11.78) and declined progressively as children aged. Only 1 child became infected after 5 years of age. Having an infected mother, an infected older sibling, and delayed weaning from a feeding bottle (ie, after 24 months of age) were all risk factors for infection.

CONCLUSIONS

Children who become infected with Helicobacter pylori are infected at a very young age, and the risk of infection declines rapidly after 5 years of age. These findings have important implications for studies on the mode of transmission of infection.

Seroprevalence of Helicobacter pylori in New York City populations originating in East Asia

Helicobacter pylori prevalence is higher in developing countries than in industrialized countries, and within the latter, higher among immigrants than among nativeborn residents. Using a point-prevalence survey, we sought to identify risk factors for H. pylori seropositivity in US urban East Asian-born populations. At a clinic in New York City, we consecutively enrolled 194 East Asian-born adults, who then responded to a survey and provided a blood sample. Assays were performed to detect IgG antibodies against whole cell (WC) and cytotoxin associated gene A (CagA) antigens of H. pylori. For this group (mean age 50.2+/-14.7 years), the mean period of residence in the United States was 11.9+/-7.7 years. The total H. pylori seroprevalence was 70.1%, with highest (81.4%) in Fujianese immigrants. Multiple logistic regression analysis indicated an independent association of H. pylori seropositivity with Fujianese origin [odds ratios (OR) =2.3, 95% confidence interval (95% CI) =1.05-5.0] and inverse associations with period in the United States (OR per year of residency in the United States =0.95, 95% CI =0.91-0.99) and with a history of dyspepsia (OR for a history of stomach pain =0.52, 95% CI =0.3-1.0). We conclude that H. pylori is highly prevalent among recent East Asian immigrants, especially among Fujianese. The protective effects of history of dyspepsia and duration in the United States suggest that these may be markers for antibiotic therapies.

Intestinal helminthiasis in Colombian children promotes a Th2 response to Helicobacter pylori: possible implications for gastric carcinogenesis

BACKGROUND

Colombians living in coastal Tumaco have a lower incidence of Helicobacter pylori-associated gastric cancer compared with residents of Pasto in the high Andes. Considering the risk for H. pylori disease seems affected by features of bacterial virulence and host polymorphisms, other poorly understood influences, such as concurrent helminthiasis, may also be important.

METHODS

Fecal samples from 211 children were tested for parasites and sera from another cohort of 159 children and 92 adults were tested for IgE and H. pylori-specific IgG.

RESULTS

Most individuals (95%) from both areas were H. pylori seropositive, with a predominant response of IgG1 followed by IgG2 and low IgG3 and IgG4 antibodies. Compared with Pasto children, Tumaco children were more commonly infected with helminths (P = 0.000), had higher serum IgE levels (P < 0.03), and had higher Th2-associated IgG1 responses to H. pylori (P < 0.0002). Other IgG isotype responses all increased with age but were not significantly different between children and adults from either area.

CONCLUSIONS

These results suggest that intestinal helminthiasis in children promotes Th2-polarizing responses to H. pylori and may decrease gastric cancer risk in these individuals later in life. Concurrent helminthiasis may alter inflammatory responses to H. pylori and thus affect the progression of gastritis to gastric atrophy, dysplasia, and cancer.

Helicobacter pylori colonization in infants in a peri-urban community in Karachi, Pakistan

BACKGROUND

The prevalence and incidence of Helicobacter pylori in children in Pakistan is not known.

OBJECTIVES

To measure the prevalence and age of acquisition of Helicobacter pylori infection/colonization in infants in a peri-urban community in Karachi, Pakistan.

SETTING

Field based epidemiologic study in a peri-urban community in Karachi, Pakistan.

METHODS

Infants aged 1 to 3 months were recruited from a birth cohort from the community. C-urea breath test (C-UBT) was performed on recruitment, and the test was repeated at 2, 3, 6, and 9 months of age.

RESULTS

One hundred forty-eight infants were recruited and had C-UBT on 319 occasions over a period of 2 years. Two hundred thirty-one=(72%) tests were positive: 80% (49/61) infants at 1 month of age, 79% (33/42) at 2 month of age, 76% (92/121) at 3 month of age, 58% (37/64) at 6 months of age, and 67% (20/30) at 9 months of age.

CONCLUSIONS

The study reveals an early colonization/infection of infants and a high prevalence of Helicobacter pylori in a peri-urban community in Karachi, Pakistan.

Significance of transiently positive enzyme-linked immunosorbent assay results in detection of Helicobacter pylori in stool samples from children

In young children, the significance of stool samples transiently positive for Helicobacter pylori antigen is unknown. As part of a larger prospective study on enteric infections, stool samples were obtained from 323 children at two time points 3 months apart and tested for H. pylori antigen using a commercially available enzyme-linked immunosorbent assay (ELISA) test. Seminested PCR for a Helicobacter-specific 16S rRNA gene was performed on all 26 pairs reverting from positive to negative (transient positives), all 4 persistent antigen-positive pairs, and 10 randomly selected persistent antigen-negative pairs. Helicobacter species were amplified from the first stool samples of 15/26 (58%) of the transient positives and 1 (25%) of 4 persistent positives. No Helicobacter species were amplified from the 10 persistent negatives. Among the 15 amplicons from transient-positive stool, H. pylori was sequenced and identified from 12 (80%; 95% confidence interval, 52% to 96%) and other Helicobacter spp. were identified from three (Helicobacter canis, Helicobacter winghamensis, and MIT 99-5504). Four of the 15 remained positive by PCR for the second (antigen-negative) stool sample, including all 3 initially identified as non-H. pylori. Helicobacter bilis was amplified from the second sample of a persistent positive. Two of eight transient positives from whom serum was available had accompanying transient elevations in anti-H. pylori antibodies. Transiently positive stool ELISAs for H. pylori are common and represent H. pylori in the majority of cases where sequences can be obtained. A not-insignificant percentage of antigen-positive stools, however, may represent other Helicobacter species.

Seroprevalence of Helicobacter pylori among children in Sana'a, Yemen

BACKGROUND

Helicobacter pylori infection is primarily acquired in early childhood. Its transmission routes are debated. The aims of this study were to determine the seroprevalence of anti-H. pylori immunoglobulin G (IgG) in Yemeni children under 10 years of age, the potential risk factors for contracting H. pylori infection and co-infection of H. pylori with intestinal parasites.

METHODS

Enzyme-labeled immunosorbent assay was used to determine the H. pylori prevalence rate among 572 healthy volunteers aged less than 10 years. Formalin ether concentration methods were used to test the prevalence of intestinal parasites (intestinal roundworms and tapeworms). In addition, we interviewed participants regarding potential risk factors for contracting H. pylori infection.

RESULTS

The seroprevalence of H. pylori antibodies was 9%. The prevalence according to age varied from 0% in children under 2 years to 12.5% in age group 9-10 years. There was a correlation between the amounts of positive antibodies and increasing age. The prevalence rate of H. pylori antibodies was also significantly associated with the practice of drinking water from reused plastic jerry cans, with poor mouth hygiene and with co-infection by intestinal parasites.

CONCLUSION

The prevalence of H. pylori antibodies in Yemen among children under 10 years of age is higher than that reported from other regions for the same age groups. Yemen shares some but not all potential risk factors for H. pylori infection with countries in which similar socioeconomic conditions are found. A possible way of eliminating H. pylori from the population would be via public health measures, i.e. preventing the reuse of plastic jerry cans, and improving sanitation and the standard of living.

Human peripheral and gastric lymphocyte responses to Helicobacter pylori NapA and AphC differ in infected and uninfected individuals

BACKGROUND

In this study, we identify the nature of the immunological response of human peripheral blood mononuclear cells (PBMC) and lamina propria gastric lymphocytes (LPL) to two Helicobacter pylori antigens, the neutrophil activating protein (NapA) and alkyl hydroperoxide reductase (AphC). These antigens were identified and selected for study based on the observation that serological recognition of these proteins was associated with H pylori negative status in humans.

AIMS

The aim was to study the serological, proliferative, and cytokine responses of PBMC and LPL, obtained from H pylori infected and uninfected individuals, to these antigens.

METHODS

Patient serum, PBMC, and LPL were used to determine antibody isotype, and proliferative and cytokine responses to recombinant forms of NapA and AphC using western blotting and ELISA.

RESULTS

Western blotting revealed antibody reactivity to recombinant NapA and AphC among the H pylori negative population studied. Both the proliferative and interferon gamma responses of PBMC and LPL to NapA and AphC were significantly higher in H pylori negative compared with H pylori positive subjects. Analysis of the IgG subclass profiles to both antigens revealed a T helper 1 associated IgG3 antibody response in uninfected individuals. However, interleukin 10 production was greater in H pylori positive individuals in response to these antigens.

CONCLUSIONS

Taken together these data are consistent with an immune response to these antigens skewed towards a T helper 1 response in the uninfected cohort.