Seroepidemiology of Helicobacter pylori infection in a cohort of children monitored from 6 months to 11 years of age

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.

Where are we today with Helicobacter pylori infection among healthy children in Saudi Arabia?

BACKGROUND/AIMS

The available studies on Helicobacter pylori (H. pylori) prevalence among healthy asymptomatic population across Saudi Arabia suffers from significant limitations. We conducted this large population-based study to estimate the H. pylori seropositivity rate among apparently healthy children in Saudi Arabia, using anti-H. pylori immunoglobulin A (IgA) and IgG serology tests, and to study the influence of H. pylori infection on growth.

MATERIALS AND METHODS

We conducted a cross-sectional study to screen apparently healthy school aged Saudi children (aged 6-15 years), attending primary and intermediate schools in Riyadh between 2014 and 2016, for H. pylori seropositivity by checking for the presence of anti-H. pylori IgG and IgA antibodies in serum specimens.

RESULTS

Out of 3551 serum specimens, 1413 cases tested seropositive for H. pylori organism (40%): 430 (12.2%) were both IgG and IgA positive, 212 (6%) and 771 (21.7%) cases showed isolated positivity for IgG or IgA, respectively. Male gender, older age, lower levels of socioeconomic status (SES), and family members >10 were significantly associated with H. pylori seropositivity. The proportion of participants with short stature was significantly more in the H. pylori seropositive group than the seronegative group (OR1.249, confidence interval [1.020-1.531], P= 0.033). There was no significant association between H. pylori seropositivity and gastrointestinal symptoms.

CONCLUSION

The prevalence of H. pylori seropositivity among apparently healthy Saudi children (40%) is intermediate compared with that in developed and developing countries. The Saudi pediatric population shows a predominant IgA-type immunological response to H. pylori infection.

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.

Association between infection with Helicobacter pylori and atopy in young Ethiopian children: A longitudinal study

BACKGROUND

Epidemiological evidence from developed countries indicates that Helicobacter pylori infection correlates with a reduced risk of atopy and allergic disorders; however, limited data are available from low-income countries.

OBJECTIVE

We examined associations between H. pylori infection in early childhood and atopy and reported allergic disorders at the age of 6.5 years in an Ethiopian birth cohort.

METHODS

A total of 856 children (85.1% of the 1006 original singletons in a population-based birth cohort) were followed up at age six and half years. An interviewer-led questionnaire administered to mothers provided information on demographic and lifestyle variables. Questions on allergic disease symptoms were based on the International Study of Asthma and Allergies in Children (ISAAC) core allergy and environmental questionnaire. Serum samples were analysed for total IgE levels and anti-H. pylori cytotoxin-associated gene A (CagA) IgG antibody using commercially available ELISA kits. Stool samples were analysed for H. pylori antigen using a rapid immunochromatographic test. The independent effects of H. pylori infection (measured at age of 3, 5 and 6.5 years) on prevalence and incidence of atopy and reported allergic disorders (measured at age of 6.5 years) were determined using multiple logistic regression.

RESULTS

In cross-sectional analysis, current H. pylori infection at age 6.5 years was inversely, though not significantly, related to prevalence of atopy and "any allergic condition" at age 6.5 years. However, detection of H. pylori infection at any point up to age 6.5 years was associated with a significantly reduced odds of both atopy and "any allergic condition" (adjusted OR AOR, 95% CI, 0.54; 0.32-0.92, P = .02, and .31; 0.10-0.94, P = .04, respectively). In longitudinal analyses, H. pylori infection at age 3 was inversely associated with incidence of atopy (AOR, 95% CI, 0.49; 0.27-0.89, P = .02). Furthermore, among H. pylori-infected children, those with a CagA+ strain had a more pronounced reduction in odds of atopy (AOR = 0.35 vs 0.63 for CagA+ vs CagA-), and this reduction reached borderline significance.

CONCLUSION

These data are consistent with the hypothesis that early exposure to H. pylori is inversely associated with atopy and allergic conditions. A possible modest protective association against atopy was observed in those infected with a more virulent CagA+ strain of H. pylori.

Epidemiology, Diagnosis, and Risk Factors of Helicobacter pylori Infection in Children

H. pylori infection is a global public health problem associated with some gastrointestinal diseases in children, especially in developing countries, since prevalence of H. pylori is low in the developed world. Both noninvasive (stool antigen test, urea breath test, and blood test) and invasive (histology, rapid urease test, and microbiological culture) tests have been utilized to detect H. pylori infection. However, a single test is not reliable enough and does not provide accurate enough data to determine H. pylori infection among children. Risk factors of H. pylori infection in children were related to ethnicities, household properties, geographic location, living conditions, water sources, type of housing, presence/absence of sewage systems, and garbage collection within the living environment. These risk factors were usually associated with the socioeconomic status of the family. This review article aims to determine the gaps in the knowledge of the epidemiology, risk factors, and diagnostic tests of H. pylori infection among children.

How to cite this article: Ozbey G, Hanafiah A. Epidemiology, Diagnosis, and Risk Factors of Helicobacter pylori Infection in Children. Euroasian J Hepato-Gastroenterol 2017;7(1):34-39.

Effect of Helicobacter pylori infection on growth trajectories in young Ethiopian children: a longitudinal study

BACKGROUND

Helicobacter pylori infection has been associated with early childhood growth impairment in high- and middle-income countries; however, few studies have examined this relationship within low-income countries or have used a longitudinal design. The possible effects of H. pylori infection on growth trajectories were examined in a cohort of young Ethiopian children.

METHODS

In 2011/12, 856 children (85.1% of the 1006 original singletons in a population-based birth cohort) were followed up at age 6.5 years. An interviewer-led questionnaire administered to mothers provided information on demographic and lifestyle variables. Height and weight were measured twice, and the average of the two measurements was used. Exposure to H. pylori infection was assessed using a rapid H. pylori stool antigen test. The independent associations of positive H. pylori infection status (measured at ages 3 and 6.5 years) with baseline height and weight (age 3 years) and height and weight growth trajectory (from age 3 to 6.5 years) were modelled using hierarchical linear models.

RESULTS

At baseline (age 3 years), the children's mean height was 85.7cm and their mean weight was 11.9kg. They gained height at a mean rate of 8.7cm/year, and weight at a mean rate of 1.76kg/year. H. pylori infection was associated with lower baseline measurements and linear height trajectory (β=-0.74cm and -0.79cm/year, respectively), after controlling for demographics and markers of socio-economic status. However, the positive coefficient was associated with quadratic growth in height among H. pylori-infected children (β=0.28, 95% confidence interval 0.07 to 0.49, p<0.01), and indicated an increase in height trajectory as the child increased in age. A non-significant difference in baseline and trajectory of weight was observed between H. pylori-infected and non-infected children.

CONCLUSIONS

These findings add to the growing body of evidence supporting that H. pylori infection is inversely associated with childhood growth trajectory, after controlling for a range of factors associated with reduced growth and H. pylori status. Further follow-up will be important to confirm possible catch-up in height trajectory among H. pylori-infected children as they grow older.

A 5-year trend of Helicobacter pylori seroprevalence among dyspeptic patients at Bahir Dar Felege Hiwot Referral Hospital, Northwest Ethiopia

Background

Helicobacter pylori infection is a major public health problem affecting half of the world's population. The prevalence of H. pylori varies in different societies and geographical locations. Thus, timely information on H. pylori epidemiology is critical to combat this infection. This study aimed to determine the seroprevalence and trend of H. pylori infection over a period of 5 years among dyspeptic patients at Bahir Dar Felege Hiwot Referral Hospital, Northwest Ethiopia.

Methods

A retrospective analysis of consecutive dyspeptic patients' records covering the period between January 2009 and December 2013 was conducted. The hospital laboratory generated the data by a serological method of detecting the antibodies for H. pylori from serum by a one-step rapid test device. Chi-square analysis was used to identify significant predictors. A P-value of <0.05 was considered as statistically significant.

Results

Among all the study subjects, 2,733 (41.6%) were found to be seropositive. The seroprevalence was significantly higher in males (43.2%) than in females (39.9%) (χ²=9; P=0.002). In terms of age groups of the patients, high rates of H. pylori were found among the participants older than 60 years (57%) (χ²=36.6; P≤0.00001). The trend analysis of H. pylori prevalence revealed a fluctuating prevalence; it was 44.5% in the year 2009 and decreased to 34% and 40% in the years 2010 and 2011, respectively. However, there was an increment to 52.5% in the year 2012, and then it decreased to 30.2% in the year 2013.

Conclusion

This study showed high seroprevalence of H. pylori among the dyspeptic patients in Bahir Dar Felege Hiwot Referral Hospital. The trend of the seroprevalence varied from year to year in the 5 consecutive years. Considering this, designing appropriate prevention and control strategies is mandatory.

Effect of early and current Helicobacter pylori infection on the risk of anaemia in 6.5-year-old Ethiopian children

BACKGROUND

Epidemiological and clinical studies in high income countries have suggested that Helicobacter pylori (H. pylori) may cause anaemia, but evidence is lacking from low income countries.We examined associations between H. pylori infection in early childhood and anaemia at the age of 6.5 years in an Ethiopian birth cohort.

METHODS

In 2011/12, 856 children (85.1 % of the 1006 original singletons in a population-based birth cohort) were followed up at age six and half. An interviewer-led questionnaire administered to mothers provided information on demographic and lifestyle variables. Haemoglobin level and red cell indices were examined using an automated haematological analyzer (Cell Dyn 1800, Abbott, USA), and stool samples analyzed for H. pylori antigen. The independent effects of H. pylori infection (measured at age 3.5 and 6.5 years) on anaemia, haemoglobin level, and red cell indices (measured at age 6.5 years) were determined using multiple logistic and linear regression.

RESULTS

The prevalence of anemia was 34.8 % (257/739), and the mean (SD) haemoglobin concentration was 11.8 (1.1) gm/dl. Current H. pylori infection at age 6.5 years was positively, though not significantly related to prevalence of anaemia (adjusted OR, 95 % CI, 1.15; 0.69, 1.93, p = 0.59). Any H. pylori infection up to age 6.5 years was significantly associated with an increased risk of anaemia at age 6.5 (adjusted OR, 95 % CI, 1.68; 1.22, 2.32, p = 0.01). A significant reduction in haemoglobin concentration and red cell indices was also observed among children who had any H. pylori infection up to age 6.5 (Hb adjusted β = -0.19, 95 % CI, -0.35 to -0.03, p = 0.01; MCV adjusted β = -2.22, 95 % CI, -3.43 to -1.01, p = 0.01; MCH adjusted β = -0.63, 95 % CI, -1.15 to - 0.12, p = 0.01; and MCHC adjusted β = -0.67, 95 % CI, -1.21 to -0.14, p = 0.01), respectively.

CONCLUSION

This study provides further evidence from a low income country that any H. pylori infection up to age 6.5 is associated with higher prevalence of anaemia, and reduction of haemoglobin level and red cell indices at age 6.5.

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.

Susceptibility to pediatric Helicobacter pylori infection correlates with the host responses of regulatory and effector T cells

BACKGROUND

Tolerance to the early acquisition of Helicobacter pylori is suggested because of a biased ratio of regulatory to effector T cells in a mice model. This study investigated whether the CD4CD25 regulatory T (Treg) and CD4+CD25- effector T (Teff) cell responses after H. pylori exposure determine H. pylori susceptibility in children.

METHODS

Treg and Teff cells from peripheral blood mononuclear cells (PBMCs) of H. pylori-infected and non-infected children were incubated with H. pylori protein. The cytokine levels and fraction of FOXP3+ to T cells were measured. FOXP3 expression was assessed by Western blotting and immunohistochemistry of gastric biopsies from dyspeptic children.

RESULTS

The fraction of FOXP3+ to CD4+CD25 high cells in PBMCs, FOXP3-positive staining and translation level in gastric tissues were higher in H. pylori-infected children than in controls (P < 0.05). The translation levels of TGF-β1 in gastric tissues were higher in H. pylori-infected children than in controls (P < 0.05). After H. pylori challenge, H. pylori-infected children had a positive net-change in TGF-β1 from Treg cells, and a negative net-change of IFN-γ from Teff cells. Paradoxically, the non-infected controls had a negative net-change in TGF-β1 from Treg cells, and a positive net-change of IFN-γ from Teff cells.

CONCLUSIONS

The host response of Treg cells with increases in FOXP3 and TGF-β1 combined with a reduction in IFN-γ by Teff cells may contribute to H. pylori susceptibility in children.

High exposure, spontaneous clearance, and low incidence of active Helicobacter pylori infection: the Sorbo San Basile study

BACKGROUND

A decreased incidence of Helicobacter pylori infection has been prospected to occur nowadays.

AIM

To evaluate the exposure to H. pylori, prevalence and incidence of active infection, and related risk factors in the general population.

METHODS

In a small town of Southern Italy (932 inhabitants), 595 (3-97 years) and 157 (12-82 years) subjects among those with no evidence of active H. pylori infection participated at baseline and 10 years later, respectively. A questionnaire was administered. Active H. pylori infection was assessed by (13) C-urea breath test (UBT). Serum VacA and CagA antibodies were determined.

RESULTS

Of 518 subjects who were evaluated by both UBT and serology, 310 (59.8%) were UBT positive, 479 (92.4%) VacA positive, and 369 (71.2%) CagA positive. Subjects UBT negative and serology positive were 169 (32%), ranging 1 (14.2%) to 29 (82.8%) from last to first decades of life. Age, female gender, and people per room were independent risk factors for subjects UBT positive compared to those UBT negative and serology positive. Ten years later, subjects who became UBT positive were four of 157 (0.25% per year) while those who became seropositive for VacA and/or CagA were 17 of 26 (6.5% per year).

CONCLUSIONS

H. pylori infection is highly dynamic with wide range of spontaneous clearance. It is easily cleared in the first decades of life, more recent years, less crowded homes, and males. It disappears and recurs more often than it was previously thought, implying that the current decline in its prevalence is due to real clearance instead of a fall in infection rate.

Clinical Application of the DiversiLab Microbial Typing System Using Repetitive Sequence-Based PCR for Characterization of Helicobacter pylori in Japan

We evaluated the DiversiLab (DL) system with universal primers, a semiautomated repetitive extragenic palindromic sequence-based polymerase chain reaction (PCR) (rep-PCR) system, for the characterization of Helicobacter pylori in Japan. All 135 isolates from Japanese patients with gastric cancer (GC, n = 55) or non-GC (n = 80) were used and subjected to the drug susceptibility examinations (amoxicillin, AMPC; metronidazole, MNZ; and clarithromycin, CAM) by E-test. There were 28 MNZ-resistant (20.7%), 35 CAM-resistant (25.9%), and 16 MNZ/CAM-resistant (11.9%) isolates. DL rep-PCR fingerprinting analysis at the level of 95% similarity revealed five major groups (A-E) and the other including 45 isolates. The occupation rates of GC-derived isolates in groups B (54.2%) and E (58.8%) were higher than in the other groups: A (26.7%), C (28.6%), D (30.0%), and the other (40.0%). Relative higher occupation rates of drug resistants, such as MNZ-, CAM- and double MNZ/CAM-resistant isolates, were observed in groups B (45.8%), C (42.6%), and D (40%). Five of eight GC-derived isolates with MNZ/CAM resistance were significantly assigned to group B (P = 0.0312, χ(2) -test). These results suggest that the isolates classified in group B have a potential to contribute to the development of severe gastric disorders. The DL system, rapid and high sensitive technology, would be widely available in clinical laboratory for pathological and epidemiological analyses even in H. pylori.

Rate ofHelicobacter pyloriInfection in Children and Clonality of Taiwan Strains

The infection rate of Helicobacter pylori in children from < 1 to 17 years old was investigated. Three techniques, namely culture, CLO test, and PCR, were employed to check the presence or absence of the organism in the antrum of the stomach. Several PCR positives without viable cultures were observed in babies of less than one year old. On the other hand, only two viable cultures were obtained from toddlers of less than two years old. The percentage of positive cultures steadily increased from 8% (3 of 42 cases) in the 0-4 years old age group to 32% (32 of 99 cases) in the 13-17 years old age group. A steady increase also was observed in the result of the CLO test. In PCR, the percentage of positives was greatly higher than that seen with the culture or CLO test. The rate of PCR positives also showed an increase with age but of a much slower rate. The overall infection rate in 295 children was 22% (64 of 295 cases) positive with culture and 76% (225 of 295 cases) with PCR, in contrast to 85% (40 of 49 cases) and 92% (43 of 47 cases), respectively, in adults. The urease activity of the H. pylori derived from children was much lower than that derived from adults (P < 0.001). Taken together, these results suggest that a child might be repeatedly infected and some infecting strains eventually might obtain a steady infection, perhaps by a strain of higher virulence such as higher urease activity. The base variations in the nucleotide sequences did not correlate to the varied urease activities or to the age of the child. The sequences, however, indicated that there were two types of strains. The strains in Taiwan appeared to be derived from the French type strain and not the English type strain. The amino acid sequences of the ureA and the phylogenetic relationship of the 29 strains indicated that the strains in Taiwan are rapidly evolving into a unique clone.

Prevalence of helicobacter pylori infection in children, a population-based cross-sectional study in west iran

OBJECTIVE

In developing countries, Helicobacter pylori infection is mainly acquired during childhood and may be a predisposing factor for peptic ulcer or gastric cancer later in life. Noninvasive diagnostic tools are particularly useful in children for screening tests and epidemiological studies. We aimed to determine the prevalence of H. pylori infection among Kurdish children in Sanandaj, West Iran.

METHODS

We used a Helicobacter Pylori Stool Antigen (HpSA) test to detect H. pylori infection. A questionnaire was used to collect data about age, sex, duration of breastfeeding, and family size. A total of 458 children aged 4 months to 15 years were enrolled in this study.

FINDINGS

The mean age of enrolled children was 5.6±5.4 years. Stool samples were positive for H. pylori in 294 (64.2%) children. The prevalence of H. pylori infection increased with age (P<0.001). We found a significant increase in the infection rate as the family size grew (P=0.005). There was no correlation between a positive H. pylori status and gender (P=0.6) or the duration of breastfeeding (P=0.8).

CONCLUSION

It seems that the prevalence of H. pylori infection is very high in children in Sanandaj. It begins at early infancy (before 4th month of age) and cumulatively increases with age.

Time to pregnancy: a computational method for using the duration of non-conception for predicting conception

An important problem in reproductive medicine is deciding when people who have failed to become pregnant without medical assistance should begin investigation and treatment. This study describes a computational approach to determining what can be deduced about a couple's future chances of pregnancy from the number of menstrual cycles over which they have been trying to conceive. The starting point is that a couple's fertility is inherently uncertain. This uncertainty is modelled as a probability distribution for the chance of conceiving in each menstrual cycle. We have developed a general numerical computational method, which uses Bayes' theorem to generate a posterior distribution for a couple's chance of conceiving in each cycle, conditional on the number of previous cycles of attempted conception. When various metrics of a couple's expected chances of pregnancy were computed as a function of the number of cycles over which they had been trying to conceive, we found good fits to observed data on time to pregnancy for different populations. The commonly-used standard of 12 cycles of non-conception as an indicator of subfertility was found to be reasonably robust, though a larger or smaller number of cycles may be more appropriate depending on the population from which a couple is drawn and the precise subfertility metric which is most relevant, for example the probability of conception in the next cycle or the next 12 cycles. We have also applied our computational method to model the impact of female reproductive ageing. Results indicate that, for women over the age of 35, it may be appropriate to start investigation and treatment more quickly than for younger women. Ignoring reproductive decline during the period of attempted conception added up to two cycles to the computed number of cycles before reaching a metric of subfertility.

Significant decrease in prevalence of Helicobacter pylori in the Czech Republic

AIM: To study possible decrease in prevalence of Helicobacter pylori (H. pylori) infection in the Czech Republic within a 10-year period.

METHODS: A total of 22 centres entered the study. The catchment areas of these centres covered cities and towns with more than 20 000 inhabitants, smaller towns (≤ 20 000 inhabitants) with surrounding villages and rural areas, and were spread over the whole country, corresponding well to the geographical distribution of the Czech population. A total of 1 837 subjects (aged 5-98 years) took part in the study, randomly selected out of 38 147 people from the general population. H. pylori infection was investigated by means of a ¹³C-urea breath test. Breath samples in duplicates were analysed using isotope ratio mass spectrometry. The cut-off point was 3.5. Social and demographic characteristics were based on data from self-completed questionnaires.

RESULTS: The overall prevalence of H. pylori infection was 23.5% (430/1826), and 4.8% (20/420) in children aged 15 or less. There was no statistically significant difference in prevalence between males (24.3%; 208/857) and females (22.9%, 222/969, P = 0.494). H. pylori infection was strongly associated with higher age, among subjects aged 55+ years, prevalence of H. pylori infection was 39.8% (252/633, P < 0.001). The highest prevalence of H. pylori infection was found among persons aged 55-64 years (43.9%, 97/221) and 75+ years (37.9%, 58/153). Among study subjects aged 15+ years, prevalence of H. pylori infection was significantly increased in those with lowest education (odds risk 3.19, 95% CI 1.87-5.47). Compared to never married (14.1%), the prevalence of H. pylori infection was statistically significantly higher among married (35.4%, 246/694, P < 0.001), divorced (36.8%, 49/133, P < 0.001) and widowed study subjects (40.2%, 45/112, P < 0.001), both in minimally and fully adjusted analysis. There was no significant difference in the prevalence of H. pylori infection between married and widowed subjects (35.4%, 246/694 vs 40.2%, 45/112, P = 0.389). There was little variation in smoking prevalence across categories of smoking and there was no evidence of an increased risk of H. pylori infection among current or past smokers in our data (odds risk 1.04 with 95% CI 0.78-1.40 for current smokers; odds ratio 0.83 with 95% CI 0.60-1.16 for former smokers). The current prevalence of H. pylori in 2011 was significantly lower compared to the prevalence reported from identical geographical areas in 2001 (23.5% vs 41.7%, P < 0.001).

CONCLUSION: The overall prevalence of H. pylori infection in the general population has fallen substantially in the Czech Republic over the past 10 years.

The association between acute lymphoblastic leukemia in children and Helicobacter pylori as the marker for sanitation

Background

Greaves “delayed infection” hypothesis suggested that Acute Lymphoblastic Leukemia (ALL) in children is caused by a lack of exposure to infection in infancy, which may be due higher standards of sanitation. We have conducted an ecologic analysis of the relationship between sanitation, using Helicobacter pylori (H. pylori) as the marker, and the incidence of childhood ALL in 127 cancer registries from 28 countries.

Results

There were inverse associations between H. pylori prevalence and ALL incidence rates in children. These associations were minor and only significant for ALL incidence rates for all cancer registries. They became non-significant and smaller in magnitude when the population source and/or the GNP per capita were added to the relationship. Furthermore, these results were unchanged when the associations were examined using the Generalized Estimating Equations.

Conclusions

Although the findings showed lower prevalence of H. pylori and improved sanitation is associated with increased incidence of childhood ALL, they do not conclusively support Greaves “delayed infection” hypothesis.

Seroepidemiology of Helicobacter pylori infection among children seen in a tertiary hospital in Uyo, southern Nigeria

BACKGROUND

Helicobacter pylori infection occurs worldwide with higher seroprevalence rates in the childhood populations of developing countries. In Nigeria, there is a dearth of information concerning its occurrence in children and infection enhancing factors. A prospective seroepidemiologic survey to determine the prevalence rate and possible associations of environmental and socio-demographic factors with its seropositivity was therefore conducted.

METHODS

The subjects were children seen at the Children's Emergency Unit of University of Uyo Teaching Hospital in southern Nigeria. Two hundred and thirty subjects, comprising 132(57.4%) males and 98(42.6%) females (male: female ratio= 1.3:1.0) with an age range of 0.5-15 years and a mean age of 5.0 (SD ± 4.0) years were recruited. The median age was 4.0 years. H. pylori immunoglobulin G (1gG) antibody was determined from serum samples stored at -200C using a commercial Enzyme-Linked Immunosorbent Assay (ELISA) kit, VicTorch.

RESULTS

The overall seroprevalence rate was 30.9% with a peak prevalence of 40.7% for the 6.0 to 10.0 years age group. H. pylori seroprevalence in our children is associated with low social class (p=0.038), increased household population (p=0.009), source of drinking water (p=0.014), type of convenience used (p=0.019) and the method of disposal of household waste (p=0.043).

CONCLUSION

The seroprevalence of Helicobacter pylori infection in Nigerian children is high and is associated with low social class, poor domestic water and poor sanitation. Improvement of water supply, human and domestic waste disposal systems and ultimately poverty alleviation would control this bacterial infection that has severe long term consequences.

Natural history of Helicobacter pylori infection in childhood: eight-year follow-up cohort study in an urban community in northeast of Brazil

BACKGROUND

Helicobacter pylori infection is acquired predominantly in childhood. There is also evidence that children loss the infection. Therefore, factors that account for children remain infected need to be investigated because once established the infection persists throughout the life unless treated.

METHODS

This study aimed to evaluate the H. pylori infection in children of a low-income community at baseline and 8years later to determine the predictor factors linked to the maintenance, acquisition, and loss of the infection using regression models of generalized estimating equations. H. pylori status was determined by (13) C-urea breath test.

RESULTS

Data from 37.7% (133/353) of the children were available. No difference between the characteristics of the included and nonincluded children was observed. The prevalence of infection increased from 53.4 to 64.7%. Thirty-nine children (29.3%) remained noninfected, 47.4% remained infected, 17.3% became infected, and 6.0% lost the infection. Factors associated with to remain infected compared with to remain noninfected included the age, increased number of children in the household, and the use of well water instead of municipal water. The acquisition of the infection was associated with the male gender.

CONCLUSION

Factors linked to remain and to gain H. pylori infection in a poor region were increased number of children in the household and the male gender. Also, the acquisition rates were higher than the loss rates, which lead to an increase in the infection prevalence with age.

Iron deficiency and Helicobacter pylori infection in children

AIM

To examine the relationship between iron deficiency (ID) and Helicobacter pylori infection in school-aged children.

METHODS

Altogether 363 children from ambulatory admission were consecutively enrolled in the study. Haemoglobin (Hb), soluble transferrin receptor (sTfR), IgG against H. pylori and IgA against tissue transglutaminase were measured. The criteria for ID were sTfR > 5.7 mg/L in children aged 7-12 years and sTfR > 4.5 mg/L in older children, for anaemia Hb < 115 g/L in the younger group and Hb < 130 g/L for older boys and Hb < 120 g/L for girls.

RESULTS

Iron deficiency was found in 17% of the children, 5% had also anaemia. H. pylori colonization was detected in 27% and serum markers for coeliac disease in 0.6% of the children. The prevalence of ID and H. pylori seropositivity was higher in older children (23% and 29%, vs 9% and 22%, respectively). Children with H. pylori were significantly shorter [length SDS 1.0 (0.98-1.01) vs 0.98 (0.97-0.99)]. Older children had risk for ID (OR 1.1, 95% CI 1.0-1.3, p = 0.03). Although the prevalence of H. pylori seropositivity was higher in the ID group, it was not significantly associated with ID in multivariate analysis.

CONCLUSION

Helicobacter pylori seropositivity was not associated with ID. The associated factor for ID was age.

Influence of sociodemographic factors on Helicobacter pylori prevalence variability among schoolchildren in Leipzig, Germany. A long-term follow-up study

BACKGROUND

Until the beginning of this decade the assumption was that the Helicobacter pylori prevalence increases with the age of the population under consideration. More and more epidemiological studies have been suggestive of constancy in Helicobacter pylori prevalence, but to date there has been no long-term follow-up study in a large group of children confirming this hypothesis.

METHODS

Following up our study of H. pylori among school starters and 2nd graders in 1998 and 2000, we conducted a third phase of this study in 2006 using the [13C]-Urea Breath Test and a detailed parent-completed epidemiological questionnaire to evaluate the development of prevalence among the overall population of 8th graders in the city of Leipzig (n = 1,905), and especially of the subgroup of participants who took part in all three study phases (n = 751).

RESULTS

The overall H. pylori prevalence was 6.5% and had not significantly changed since 1998 and 2000 (6.1%, 5.7% respectively). However, we noticed a significant lower prevalence in the subgroup that participated in all study phases (2.7%). Moreover, we observed a dependence of prevalence on distribution of sociodemographic risk factors such as foreign nationality of at least one parent, birth outside of Germany, low parental education and unemployment, and > or = 2 older siblings.

CONCLUSION

The variability in prevalence is most likely a result of unequal sociodemographic family backgrounds.

Helicobacter pylori infection among a pediatric population with sickle cell disease

OBJECTIVES

Recurrent abdominal pain (RAP) is a common presenting symptom in children with sickle cell disease (SCD). This may be as a result of complications of the disease, surgical problems, or Helicobacter pylori gastritis. The prevalence of H pylori infection in SCD children is not known. This study aimed to determine the prevalence and association of H pylori infection with RAP in SCD children.

METHODS

This was a prospective case-control study conducted at the Lagos State University Teaching Hospital, Nigeria, involving SCD children (subject, n = 118) and non-SCD children (control, n = 118) matched for age, sex, and socioeconomic status. Seroprevalence status of the children was determined by measuring immunoglobulin G antibodies against H pylori using enzyme-linked immunosorbent assay that had been validated for pediatric use.

RESULTS

The overall prevalence of H pylori infection was 155 of 236 (SCD, 67.8%; non-SCD, 63.6%; OR, 1.1; 95% CI, 0.89-1.28; p = .493). The prevalence increased with age in both SCD and non-SCD children and was significantly highest at the age of 6 to 10 years (p < .001 in each case). H pylori infection was significantly associated with socioeconomic status of the parents (OR, 4.25; 95% CI, 1.49-12.1; p = .004) but not significantly associated with RAP in SCD children (OR, 1.21: 95% CI, 0.55-2.66; p = .632).

CONCLUSIONS

Prevalence of H pylori infection is high in SCD and non-SCD children in Lagos, Nigeria. There was no significant association between H pylori infection and recurrent abdominal pain in SCD children.

Helicobacter pylori and gastritis: Untangling a complex relationship 27 years on

Since its' introduction by Warren and Marshall 27 years ago, Helicobacter pylori (HP) has become the linchpin in our understanding of important gastric conditions including gastritis, intestinal metaplasia (IM), gastric/duodenal ulcers (GU/DU), Mucosal Associated Lymphoid Tumour (MALToma) and gastric cancer. Initially named Campylobacter pyloridis, it was re-named HP when biochemical and genetic characterization of the organism showed that it was not a member of the Campylobacter genus. The finding in 1983 was seminal. It is now recognized that HP is the most common chronic human bacterial infection and it is the most common cause of gastritis. It is strongly implicated in the development of peptic ulcer disease and gastric neoplasms. In the years since its' discovery, much headway has been made in the understanding of this ubiquitous organism that had remained elusive, with much work focused on eradication, in part driven by pharmaceutical research and development. Standard triple therapy emerged to eradicate HP. However, with the emergence of HP resistance, newer regimes have been put forth that include quadruple therapy, sequential therapy and a dizzying array of other combinations bent on eradicating HP. Much less is known about the natural history of HP, the different faces of HP internationally, HP eradication and its effect on gastritis, IM, GU/DU and gastric cancer. This review will address the changing face of HP in 2011.

Seroprevalence of Helicobacter pylori infection among children of low socioeconomic level in São Paulo

CONTEXT AND OBJECTIVE

Helicobacter pylori infection is mainly acquired during childhood, and is associated with significant morbidity in adults. The aim here was to evaluate the seroprevalence and risk factors of H. pylori infection among children of low socioeconomic level attended at a public hospital in São Paulo, Brazil.

DESIGN AND SETTING

Cross-sectional study, among patients attended at an outpatient clinic.

METHODS

326 children were evaluated (150 boys and 176 girls; mean age 6.82 ± 4.07 years) in a cross-sectional study. Patients with chronic diseases or previous H. pylori treatment, and those whose participation was not permitted by the adult responsible for the child, were excluded. The adults answered a demographic questionnaire and blood samples were collected. The serological test used was Cobas Core II, a second-generation test. Titers > 5 U/ml were considered positive.

RESULTS

H. pylori infection was diagnosed in 116 children (35.6%). Infected children were older than uninfected children (7.77 ± 4.08 years versus 5.59 ± 3.86 years; p < 0.0001). The seroprevalence increased from 20.8% among children aged two to four years, to 58.3% among those older than 12 years. There were no significant relationships between seropositivity and gender, color, breastfeeding, number of people in the home, number of rooms, bed sharing, living in a shantytown, maternal educational level, family income or nutritional status. In multivariate analysis, the only variable significantly associated with H. pylori seropositivity was age.

CONCLUSION

Infection had intermediate prevalence in the study population, and age was associated with higher prevalence.

Helicobacter pylori in apparently healthy children aged 0-12 years in urban Kampala, Uganda: a community-based cross sectional survey

Background

Helicobacter pylori is one of the most common causes of bacterial infection in human beings. Studies have showed a high prevalence of Helicobacter pylori among people in low-income countries and colonization early in life. A monoclonal antigen test, performed on faeces, HpSA^®ImmunoCardSTAT, has a high sensitivity, specificity and accuracy and the faecal test can be performed in all ages, also in resource-limited settings. The main objective of this study was to determine the prevalence and factors associated with Helicobacter pylori colonization in apparently healthy children aged 0-12 years in urban Kampala, Uganda.

Method

We tested 427 apparently healthy children, age 0-12 years (211 males, 216 females), in a cross sectional survey for Helicobacter pylori colonization using HpSA ^®ImmunoCardSTAT. A short standardized interview with socio-demographic information and medical history was used to assess risk factors.

Results

The overall prevalence of Helicobacter pylori in the 427 children was 44.3% (189 out of 427). Early colonization was common, 28.7%, in children younger than 1 year of age. The age specific rates were 46.0% in children age 1- < 3 years, 51.7% in children age 3- < 6 years, 54.8% in children age 6- < 9 years and 40.0% in children age 9- < 12 years. There was a significant difference in prevalence by gender; female 38.5% versus male 49.8% and by type of housing; permanent house 38.5% versus semi-permanent house 48.6%. Congestive living and education level of the female caretaker showed a clear trend for a difference in prevalence. Factors independently associated with Helicobacter pylori colonization included: drugs taken last three months, using a pit latrine, sources of drinking water and wealth index.

Conclusion

The prevalence of Helicobacter pylori colonization among urban Ugandan children is high at an early age and increases with age. The impact of Helicobacter pylori colonization on children's health in Uganda needs to be further clarified.

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.

Helicobacter species DNA in liver and gastric tissues in children and adolescents with chronic liver disease

OBJECTIVE

Enterohepatic Helicobacter species (EHS) have previously been found in adults with hepatobiliary diseases. Here, we report the prevalence of Helicobacter pylori and EHS in liver and gastric tissue in children and adolescents with chronic liver disease (CLD).

MATERIAL AND METHODS

Seventy-seven consecutive children and adolescents with CLD with or without ulcerative colitis or Crohn's disease (UC/CD) were investigated. Tissue samples were analysed using a Helicobacter genus-specific 16S rDNA polymerase chain reaction (PCR) assay and DNA-sequence analysis. Sera from 61 subjects were also analysed using enzyme immunoassay and immunoblotting.

RESULTS

The Helicobacter PCR was positive in 3/23 (13%) livers from patients with primary sclerosing cholangitis and UC, and in 1/2 livers from patients with autoimmune hepatitis (AIH) and UC. Sequenced PCR products matched the 16S rDNA of H. hepaticus, H. muridarum, H. canis, and H. pylori, respectively. H. ganmani and H. bilis were detected in gastric tissues from two AIH patients. H. hepaticus and H. pullorum were found in livers from two patients with acute liver failure and intrahepatic cholestasis. Antibody reactivity to Helicobacter cell-surface proteins was negative.

CONCLUSIONS

H. pylori and EHS can be detected in the livers of some patients with UC and concomitant liver disease, as well as in other children with liver diseases. Multicentre studies from different locations are needed to find out whether these bacteria play a pathogenetic role or whether their presence is an epiphenomenon.

The association of drinking water quality and sewage disposal with Helicobacter pylori incidence in infants: the potential role of water-borne transmission

The mode of transmission of Helicobacter pylori, a bacterium causing gastric cancer and peptic ulcer disease, is unknown although waterborne transmission is a likely pathway. This study investigated the hypothesis that access to treated water and a sanitary sewerage system reduces the H. pylori incidence rate, using data from 472 participants in a cohort study that followed children in Juarez, Mexico, and El Paso, Texas, from April 1998, with caretaker interviews and the urea breath test for detecting H. pylori infection at target intervals of six months from birth through 24 months of age. The unadjusted hazard ratio comparing bottled/vending machine water to a municipal water supply was 0.71 (95% confidence interval (CI): 0.50, 1.01) and comparing a municipal sewer connection to a septic tank or cesspool, 0.85 (95% CI: 0.60, 1.20). After adjustment for maternal education and country, the hazard ratios decreased slightly to 0.70 (95% confidence interval: 0.49, 1.00) and 0.77 (95% confidence interval: 0.50, 1.21), respectively. These results provide moderate support for potential waterborne transmission of H. pylori.

Helicobacter pylori infection in children: population-based age-specific prevalence and risk factors in a developing country

AIM

We estimated the prevalence, age of acquisition and risk factors for Helicobacter pylori (H. pylori) seroprevalence in children aged 1-15 years.

METHODS

Exposure was assessed using ELISA. Parents responded to a questionnaire regarding number of individuals sharing house, rooms, water source, latrines, housing and assessment of socioeconomic status (SES) by Hollingshead Index.

RESULTS

Serum of 1976 children was tested. Helicobacter pylori seropositivity in children aged 11-15 years was 53.5% (OR: 2.0, 95% CI: 1.58-2.5). It increased with moderate crowding index (CRI) of 2-4 to 45.9% (OR: 1.23, 95% CI: 0.92-1.63) and to 51.2% with CRI >4 (OR: 1.52, 95% CI: 1.12-2.06). In middle SES, seropositivity was 50.5% (331/655) (OR: 1.7, 95% CI: 1.29-2.35), whereas in lower SES, it was 47.1% (500/1062) (OR: 1.5, 95% CI: 1.1-2.0). Multivariate analysis showed that Helicobacter pylori seroprevalence was high in children aged 6-10 and 11-15 years (OR: 1.5, 95% CI: 1.2-1.9 and OR: 1.9, 95% CI: 1.56-2.47 respectively), in lower-middle SES (OR: 1.6, 95% CI: 1.2-2.1 and OR: 1.5, 95% CI: 1.10-2.0 respectively) and in uneducated fathers (OR: 1.58, 95% CI: 1.27-1.95).

CONCLUSION

Helicobacter pylori seropositivity increases with age, in low-middle SES and is related to father's educational status. Reducing H. pylori seroprevalence will require improvement in sanitary conditions and educational status of the population.

Antibiotics taken for other illnesses and spontaneous clearance of Helicobacter pylori infection in children

PURPOSE

Factors that determine persistence of untreated Helicobacter pylori (H. pylori) infection in childhood are not well understood. We estimated risk differences for the effect of incidental antibiotic exposure on the probability of a detected clearance at the next test after an initial detected H. pylori infection.

METHODS

The Pasitos Cohort Study (1998-2005) investigated predictors of H. pylori infection in children from El Paso, Texas, and Juarez, Mexico. Children were screened for infection at 6-month target intervals from 6 to 84 months of age, using the 13C-urea breath test corrected for body-size-dependent variation in CO2 production. Exposure was defined as courses of any systemic antibiotic (systemic) or those with anti-H. pylori action (HP-effective) reported for the interval between initial detected infection and next test. Binomial regression models included country of residence, mother's education, adequacy of prenatal care, age at infection, and interval between tests.

RESULTS

Of 205 children with a test result and antibiotic data following a detected infection, the number of children who took > or =1 course in the interval between tests was 74 for systemic and 33 for HP-effective. The proportion testing negative at the next test was 66% for 0 courses, 72% for > or =1 systemic course, and 79% for > or =1 HP-effective course. Adjusted risk differences (95%CI) for apparent clearance, comparing > or =1 to 0 courses were 10% (1-20%) for systemic and 11% (0-21%) for HP-effective.

CONCLUSIONS

Incidental antibiotic exposure appears to influence the duration of childhood H. pylori infection but seems to explain only a small portion of spontaneous clearance.

Helicobacter pylori infection in developing countries: the burden for how long?

Approximately 50% (over 3 billion) of the world populations are known to be infected with Helicobacter pylori , mainly in the developing countries . Among those, hundreds of millions of people develop peptic ulceration during their lifetime and still tens of millions might progress to gastric cancer. Possible modes of H. pylori transmission generally described are through direct contact between family members and also through contaminated water and food. Because the high prevalence of infection occurs mainly in developing countries and because the test-and-treat strategy puts a huge economic burden on many of these countries, it is time to take an immediate action toward this bacterial infection and adopt a strategy to prevent it. To address this issue, an updated prevalence of infection, modes of transmission, economics of infection and preventative measures to block the infection process have been discussed.

Vertical Helicobacter pylori transmission from Mongolian gerbil mothers to pups

To identify the time frame and route of mother-to-child Helicobacter pylori infection, a Mongolian gerbil model was used. Four-week-old female Mongolian gerbils were infected with H. pylori, and then mated with uninfected males 2 months after infection. The offspring were sacrificed weekly after birth, and then serum, mother's milk from the stomach and gastric tissues were obtained from pups. Anti-H. pylori antibody titres were measured in sera and maternal milk using an ELISA. The stomach was cut in two in the sagittal plane, and then H. pylori colonization in mucosa was confirmed by culture and real-time RT-PCR in one specimen and by immunochemical staining in the other. Faeces and oral swabs were obtained from infected mothers, and H. pylori 16S rRNA was measured using real-time RT-PCR. H. pylori was not identified in cultures from the gastric mucosa of pups delivered by infected mothers, but H. pylori 16S rRNA was detected from 4 weeks after birth, suggesting that Mongolian gerbil pups become infected via maternal H. pylori transmission from 4 weeks of age. The anti-H. pylori antibody titre in sera of pups from infected mothers was maximum at 3 weeks of age and then rapidly decreased from 4 weeks of age. High antibody titres in mother's milk were detected during the suckling period, and GlcNAcα was detectable at 2–4 weeks of age, but disappeared as the offspring aged. Thus H. pylori seems to infect Mongolian gerbil pups from 4 weeks of age, in parallel with decreasing GlcNAcα expression in the gastric mucosa. These results suggested that H. pylori infection of Mongolian gerbil pups occurs via faecal–oral transmission from an infected mother.

Pediatric Helicobacter pylori isolates display distinct gene coding capacities and virulence gene marker profiles

Helicobacter pylori strains display remarkable genetic diversity, and the presence of strains bearing the toxigenic vacA s1 allele, a complete cag pathogenicity island (PAI), cagA alleles containing multiple EPIYA phosphorylation sites, and expressing the BabA adhesin correlates with development of gastroduodenal disease in adults. To better understand the genetic variability present among pediatric strains and its relationship to disease, we characterized H. pylori strains infecting 47 pediatric North American patients. Prevalence of mixed infection was assessed by random amplified polymorphic DNA analysis of multiple H. pylori clones from each patient. Microarray-based comparative genomic hybridization was used to examine the genomic content of the pediatric strains. The cagA and vacA alleles were further characterized by allele-specific PCR. A range of EPIYA motif configurations were observed for the cagA gene, which was present in strains from 22 patients (47%), but only 19 (41%) patients contained a complete cag PAI. Thirty patients (64%) were infected with a strain having the vacA s1 allele, and 28 patients (60%) had the babA gene. The presence of a functional cag PAI was correlated with ulcer disease (P = 0.0095). In spite of declining rates of H. pylori infection in North America, at least 11% of patients had mixed infection. Pediatric strains differ in their spectrum of strain-variable genes and percentage of absent genes in comparison to adult strains. Most children were infected with H. pylori strains lacking the cag PAI, but the presence of a complete cag PAI, in contrast to other virulence markers, was associated with more severe gastroduodenal disease.

Evidence of intra-familial transmission of Helicobacter pylori by PCR-based RAPD fingerprinting in Bangladesh

Helicobacter pylori is a genetically diverse bacterial species, which has facilitated adaptation to new hosts and persists worldwide. The main objective of this study was to explore intra-familial transmission of H. pylori in Bangladesh. We characterized H. pylori in 35 families including 138 family members using random amplified polymorphic DNA (RAPD) fingerprinting. Forty-six percent of H. pylori isolated from the mother shared a related genotype with strains isolated from their children. Twenty-nine percent of H. pylori isolates of the mother are related to the youngest children. Only 6% of the parents shared related genotype of H. pylori. These findings suggest that mother-to-child transmission occurs in early childhood and is the most probable route of transmission of H. pylori in Bangladesh.

Persistent H. pylori colonization in early acquisition age of mice related with higher gastric sialylated Lewis x, IL-10, but lower interferon-γ expressions

Background

H. pylori infection is less prevalent in childhood. This study validated whether the rates of H. pylori colonization depend on different acquisition ages, and correlate with the different gastric Lewis antigens or cytokine expressions after H. pylori acquisition.

Methods

We applied a young (7-day-old) C57BL/6 mice group (n = 50) and adult (6-week-old) C57BL/6 mice group (n = 50). In each group, 30 mice were challenged with H. pylori and 20 mice served as naïve control. The success of H. pylori colonization was assessed on the 2^nd week and the 8^th week, respectively. The intensity of the Lewis x, sialylated Lewis x(sialyl-Le^x), and cytokine expressions, including TNF-α, IFN-γ, IL-6, IL-10, and IL-1β, were immunochemically stained and graded.

Results

On the 2^nd week after H. pylori challenge, the colonization rates of H. pylori were similar between the young mice group and the adult mice group (89% vs. 100%, P > 0.05). However, on the 8^th week, the H. pylori colonization rate was significantly lower in the young mice group than in the adult mice group (53% vs. 95%, P = 0.003). On the 8^th week, the young mice with a persistence of H. pylori colonization had higher sialyl-Le^x, higher IL-10, and lower IFN-γ than those of the mice that lost colonization during the 2^nd to the 8^th week (P < 0.05).

Conclusion

The persistence of H. pylori colonization could be an acquisition-age determinant process. After H. pylori exposure at an early acquisition age, the host response with a higher sialyl-Le^x and IL-10, but a lower IFN-γ correlates to the consequent persistence of H. pylori colonization.

Lipopolysaccharide diversity evolving in Helicobacter pylori communities through genetic modifications in fucosyltransferases

Helicobacter pylori persistently colonizes the gastric mucosa of half the human population. It is one of the most genetically diverse bacterial organisms and subvariants are continuously emerging within an H. pylori population. In this study we characterized a number of single-colony isolates from H. pylori communities in various environmental settings, namely persistent human gastric infection, in vitro bacterial subcultures on agar medium, and experimental in vivo infection in mice. The lipopolysaccharide (LPS) O-antigen chain revealed considerable phenotypic diversity between individual cells in the studied bacterial communities, as demonstrated by size variable O-antigen chains and different levels of Lewis glycosylation. Absence of high-molecular-weight O-antigen chains was notable in a number of experimentally passaged isolates in vitro and in vivo. This phenotype was not evident in bacteria obtained from a human gastric biopsy, where all cells expressed high-molecular-weight O-antigen chains, which thus may be the preferred phenotype for H. pylori colonizing human gastric mucosa. Genotypic variability was monitored in the two genes encoding α1,3-fucosyltransferases, futA and futB, that are involved in Lewis antigen expression. Genetic modifications that could be attributable to recombination events within and between the two genes were commonly detected and created a diversity, which together with phase variation, contributed to divergent LPS expression. Our data suggest that the surrounding environment imposes a selective pressure on H. pylori to express certain LPS phenotypes. Thus, the milieu in a host will select for bacterial variants with particular characteristics that facilitate adaptation and survival in the gastric mucosa of that individual, and will shape the bacterial community structure.

A novel noninvasive genotyping method of Helicobacter pylori using stool specimens

BACKGROUND & AIMS

The source(s) of the infection and the route(s) of transmission of Helicobacter pylori have not yet been clarified. This is to introduce a noninvasive protocol allowing molecular typing of H pylori using stool specimens.

METHODS

The genotyping method is based on 2 H pylori-specific biprobe real-time polymerase chain reaction assays using fragments of the glmM and the recA genes as target sequences. Discrimination between strains results from differences in the melting temperature during melting curve analysis. In case of identical melting temperatures in both assays, sequence analysis of the glmM amplicon was performed to confirm strain identity. The method was validated using gastric biopsy specimens and stool specimens of 97 unrelated individuals suffering from abdominal pain and stool specimens of members of 10 families in Austria (infected index child and family members) and 8 African households.

RESULTS

Of the 97 patients, 27 were infected as shown by culture, histology, and rapid urease test. The sensitivity of each of the assays was 100% in gastric biopsy specimens and 92.2% in stool specimens; the specificity was 100%. The discriminatory capacity of the method was 100%. Clonal identities were found in 9 of 10 (90%) European and 7 of 8 (87.5%) African households. In 2 African households, 2 different clonal lineages each were found.

CONCLUSIONS

The genotyping protocol introduced allows for both accurate detection and discrimination of H pylori strains in stool samples. Large-scale studies using this protocol may contribute to the clarification of the transmission pathways of infection with H pylori.

Helicobacter pylori antigen in stool is associated with SIDS and sudden infant deaths due to infectious disease

Infection with Helicobacter pylori has been proposed to be a common cause of Sudden Infant Death Syndrome (SIDS). We investigated the frequency of H. pylori infection in 160 infant deaths and 156 live controls by means of the Helicobacter pylori stool antigen (HpSA) immunoassay. Histology was performed in 26 randomly selected cases. H. pylori antigen was detected in 8% (12/156) of the live controls compared with 25% (30/122) of SIDS cases (p < 0.001), 53% (9/17) of deaths due to infection (p < 0.001), and 9% (1/11) of accidental/violent deaths (p = 0.60). In the classic age peak for SIDS, 1-5 mo, 31% (21/67) of SIDS cases were HpSA positive compared with 1.5% (1/68) of live controls (p < 0.001). Rod-like immunoperoxidase positive H. pylori organisms were identified in 7/12 HpSA positive gastric antrum sections compared with 2/14 HpSA negative (p = 0.038). Significantly elevated IL-6 levels in cerebrospinal fluid representing signs of central immune stimulation were demonstrated in HpSA positive SIDS victims compared with HpSA negative victims (p = 0.045). Detection of H. pylori antigen in stool is associated with SIDS and deaths due to infections. We hypothesize that H. pylori infection in infancy may be involved as the triggering pathogen for sudden death during the first 5 month after birth.

Toxigenic Helicobacter pylori infection precedes gastric hypochlorhydria in cancer relatives, and H. pylori virulence evolves in these families

PURPOSE

Helicobacter pylori infection by virulent strains is associated with gastric adenocarcinoma. We aimed to determine whether infection with virulent H. pylori preceded precancerous gastric hypochlorhydria and atrophy in gastric cancer relatives and quantify the extent of virulence factor evolution.

EXPERIMENTAL DESIGN

H. pylori strains from 51 Scottish gastric cancer relatives were characterized by genetic fingerprinting and typing the vacuolating cytotoxin gene (vacA), the cytotoxin-associated gene (cagA), and housekeeping genes. We phenotyped strains by coculture with gastric epithelial cells and assessing vacuolation (microscopy), CagA tyrosine phosphorylation (immunoblot), and interleukin-8 secretion (ELISA).

RESULTS

Toxigenic (vacA type s1/m1) H. pylori was associated with precancerous gastric hypochlorhydria (P<0.01). Adult family members with this type of H. pylori had the same strain as currently noncohabiting adult family members in 68% cases, implying acquisition during childhood from each other or a common source. We analyzed different isolates of the same strain within families and showed that H. pylori commonly microevolved to change virulence: this occurred in 22% individuals and a striking 44% cases where the strain was shared within families. Microevolution in vacA occurred by extragenomic recombination and in cagA by this or duplication/deletion. Microevolution led to phenotypic changes in virulence. Passage of microevolved strains could be tracked within families.

CONCLUSIONS

Toxigenic H. pylori infection precedes and so likely causes gastric hypochlorhydria, suggesting that virulent H. pylori increases cancer risk by causing this condition. Microevolution of virulence genes is common within families of gastric cancer patients and changes H. pylori virulence.

Spontaneous elimination of Helicobacter pylori infection in a cohort of asymptomatic school children by enzyme-linked immunosorbent assay polyclonal antigen in stool

GOAL

To determine the natural evolution of the Helicobacter pylori infection through the fecal antigen of the H. pylori test in a cohort of school children during 2 consecutive years.

BACKGROUND

Studies have suggested that the spontaneous elimination rate is higher in developing countries, possibly owing to higher incidence rate.

STUDY

One hundred twelve children attending a day care center for the sons and daughters of university employees were evaluated yearly in a 2-year period using the H. pylori stool antigen test. Parents answered a questionnaire with demographic data at baseline. The test was performed according to previously standardized procedures, and results lesser than 0.140 were regarded as negative; higher than 0.016 were regarded as positive.

RESULTS

Age ranged from 0.7 to 7.48 years (3.67+/-1.98 y) at baseline, with 58% female and 42% male. H. pylori prevalence was 12.5% (14/112). There was a trend to associate low income (P=0.06), ethnicity non-white (P=0.075), and smaller house (P=0.079) to H. pylori infection at baseline in univariate analysis. Nevertheless, age was the only variable associated to prevalence at multivariate analysis. There was no significant association between H. pylori infection and intestinal parasites. There was only one new infection during the study period (incidence rate 0.53%), and 4 children cleared the infection (elimination rate 2.15%). All those children were older than 4 years.

CONCLUSIONS

Spontaneous eradication of the infection was more frequent than incidence of infection in this cohort.

Is there a link between atrial fibrillation and certain bacterial infections?

The pathogenesis of atrial fibrillation (AF), the most common cardiac dysrhythmia, remains unknown. However, many recent studies point to an association between AF and inflammation because of a demonstrable significant correlation between the dysrhythmia and various biomarkers of inflammation. For example, C-reactive protein (CRP), a sensitive biomarker of systemic inflammation, has been reported to be significantly higher in patients with AF compared with a control group with no history of atrial dysrhythmias. Histological anomalies in the atria of patients with AF have also been observed. These anomalies may have an inflammatory basis, although it is not known if the structural changes within the atria of patients with AF are a cause or consequence of the dysrhythmia. Given the suggested involvement of inflammation with this dysrhythmia, an initiating factor for inflammation has been sought. Chronic bacterial infection is the most likely event to initiate and maintain an inflammatory process. Recently, bacteria infections have been hypothesized to be involved in the pathogenesis of AF, and Helicobacter pylori and Chlamydia pneumoniae are two bacteria that have aroused interest. Here, we give a brief overview of AF and then specifically explore the recent evidence that suggests that AF may be caused by bacterial infection(s) in certain patients.

How labile is gastric infection with H pylori?

It is known that patients infected with H pylori can spontaneously become free from infection, and that the reverse change can occur. The time-scale of these conversions is expressed as percentages per year. Since they have been investigated in terms of serology, the changes are called sero-reversion and sero-conversion respectively. Using serological evidence to investigate these phenomena is open to the criticisms that positive serology can be present in the absence of all other evidence of infection, and that a time-lag of 6-12 mo or longer can occur between eradication of the infection and sero-reversion. Investigations using direct evidence of current infection are sparse. The few that exist suggest that some individuals can seroconvert or sero-revert within six to twelve weeks. If these findings are confirmed, it means that some patients have an ability that is variable in time to resist, or spontaneously recover from, H pylori infection. Evidence suggests that the deciding factor of susceptibility is the level of gastric secretion of acid.

Detection rate of Helicobacter pylori stool antigen in newborn infants and small children

AIMS

To investigate the prevalence of H. pylori antigen in the stools of Norwegian neonates and small children.

METHODS

A total of 249 children aged 0 days-3 years were tested for the presence of H. pylori antigen in feces using the HpSA immunoassay. For verification purposes, a selection of samples were analyzed with PCR targeting the 16 S rDNA Helicobacter gene.

RESULTS

H. pylori antigen in stool was detected in 52% (36/69) of the neonates, in 15% (7/46) of infants aged 7 days-1 month, and in 5% (7/134) of children aged 1 month-3 years. In neonates, H. pylori antigen detection was significantly associated with mode of delivery: 59% (30/51) with uncomplicated vaginal births were HpSA positive compared to only 10% (1/10) of infants delivered by cesarean section (P=0.02). Positive PCR results were found in 35% (9/26) of HpSA positive samples. Sequencing of PCR products revealed 97-100% homology with gene sequences from both H. pylori and other Helicobacter species.

CONCLUSIONS

The low H. pylori antigen detection rate in children >1 month of age is in accordance with previous prevalence studies from Western countries. The unexpected finding of a high H. pylori antigen detection rate in neonates suggests that transient colonization may occur in the neonatal period.

Helicobacter pylori genome variability in a framework of familial transmission

BACKGROUND

Helicobacter pylori infection is exceptionally prevalent and is considered to be acquired primarily early in life through person-to-person transmission within the family. H. pylori is a genetically diverse bacterial species, which may facilitate adaptation to new hosts and persistence for decades. The present study aimed to explore the genetic diversity of clonal isolates from a mother and her three children in order to shed light on H. pylori transmission and host adaptation.

RESULTS

Two different H. pylori strains and strain variants were identified in the family members by PCR-based molecular typing and sequencing of five loci. Genome diversity was further assessed for 15 isolates by comparative microarray hybridizations. The microarray consisted of 1,745 oligonucleotides representing the genes of two previously sequenced H. pylori strains. The microarray analysis detected a limited mean number (+/- standard error) of divergent genes between clonal isolates from the same and different individuals (1 +/- 0.4, 0.1%, and 3 +/- 0.3, 0.2%, respectively). There was considerable variability between the two different strains in the family members (147 +/- 4, 8%) and for all isolates relative to the two sequenced reference strains (314 +/- 16, 18%). The diversity between different strains was associated with gene functional classes related to DNA metabolism and the cell envelope.

CONCLUSION

The present data from clonal H. pylori isolates of family members do not support that transmission and host adaptation are associated with substantial sequence diversity in the bacterial genome. However, important phenotypic modifications may be determined by additional genetic mechanisms, such as phase-variation. Our findings can aid further exploration of H. pylori genetic diversity and adaptation.

Epidemiology and pathophysiology of Helicobacter pylori infection in children

Helicobacter pylori is one of the commonest bacterial pathogens in human. The organism is associated with development of peptic ulcer diseases, lymphoproliferative disorders and gastric cancer. Residence in a developing country, poor socio-economic conditions and genetic predisposition are regarded as risk factors. Prevalence of infection is higher in developing countries and re-infection is higher among under five children. It is transmitted mainly through feco-oral route in developing countries and gastro-oral route in developed nations. Transmission of 'close-contact infection' depends on the degree of mixing and age-distribution between susceptible and infected individuals. Host and bacterial factors with interaction of environment contribute pathogenicity. H. pylori cytotoxin-associated geneA (cagA), vacuolating toxinA (vacA) and adherence factors to gastric epithelium have been linked to enhanced pathogenicity of the bacterium. Host genetic polymorphism of cytokines, related legends, receptors and enzymes influence H. pylori infection.