Serodiagnosis of Helicobacter pylori infection in childhood

E-Cadherin Protein as a Potential Marker for Gastric Cancer and Its Association with Helicobacter Pylori- Induced Gastritis and Gastric Ulcer

BACKGROUND

Gastric cancer is still the main health threat being the third leading cause of deaths from cancers in the world. The major risk behind the gastric cancer is that it remains asymptomatic in the early stages and in (97%) cases it metastasizes to other organs. Gastric cancer is a multifactorial disease in which Helicobacter pylori (H. pylori) has been known as a risk factor. However, patients with gastritis, especially atrophic gastritis and gastric ulcer have been shown to be at an increased risk for developing gastric cancer.

METHODS

This study included measuring the serum levels of E-Cadherin protein, carbohydrate antigen 19-9 (CA19-9) and carcinoembryonic antigen (CEA) in 30 patients diagnosed with gastritis, 20 gastric ulcer patients, 20 gastric cancer patients and in 20 healthy volunteers serving as the control group.

RESULTS

Infection with H. pylori was diagnosed by serology (IgA and IgG antibodies) as well as by rapid urease test (RUT) and histology. The results showed that 50 (71.4%) of the patients were positive for H. pylori. Levels of E-Cadherin were increased significantly in all patients in comparison to the control group with a large significant increase in the gastric cancer group. The levels of E-Cadherin were also significantly increased in H. pylori infected patients compared to H. pylori negative patients. A non-significant difference in the levels of CA19-9 and CEA was observed in all patients in comparison to healthy controls.

CONCLUSION

This study concluded that serum E-Cadherin could be considered as a potential marker in diagnosis of gastric cancer.

Development and validation of a whole-cell ELISA for serologically diagnosing Helicobacter pylori infection in Brazilian children and adults: a diagnostic accuracy study

BACKGROUND

Serological tests are practical, with low cost, but no noninvasive tests are available for diagnosing Helicobacter pylori (H. pylori) infection in Brazil. The aim here was to develop and validate enzyme-linked immunosorbent assay (ELISA) serological tests to detect anti-H. pylori immunoglobulin G antibodies, based on cultured strains from Brazilian patients.

DESIGN AND SETTING

Cross-sectional, diagnostic accuracy study comparing a locally developed and validated ELISA and invasive tests among dyspeptic patients at two public hospitals in São Paulo, Brazil.

METHODS

An ELISA test was prepared using whole-cell antigen from 56 strains. After genotypic characterization, it was standardized and optical density (OD) cutoffs were determined based on the serum antibody response of 100 H. pylori-negative samples, compared with 82 H. pylori-positive samples. Validation was performed on 174 symptomatic patients.

RESULTS

The optimal OD cutoffs established (for monoclonal and polyclonal tests, respectively) were 0.167 and 0.164; overall ELISA sensitivity: 84.3%, 78.9%; specificity: 88.6%, 90.6%; positive predictive value (PPV): 75.4%, 80%; negative predictive value (NPV): 93.1%, 81.8%; accuracy: 87.3%, 86.2%; child and adolescent ELISA sensitivity: 74.2%, 81.8%; specificity: 90.8%, 86.7%; PPV: 66.6%, 84.3%; NPV: 95.8%, 84.8%; accuracy: 88.5%, 84.6; adult ELISA sensitivity: 84.4%, 75%; specificity: 86.9%, 93%; PPV: 81.8%, 78.3%; NPV: 88.9%, 91.8%; accuracy: 85.9%, 88.5%.

CONCLUSION

The polyclonal serological test developed using local strains presented better diagnostic performance among children and adolescents, while the monoclonal test was better among adults. The results from both tests suggest that these in-house serological tests could be used to detect anti-H. pylori antibodies in our population, for screening purposes.

Non-invasive diagnostic tests for Helicobacter pylori infection

BACKGROUND

Helicobacter pylori (H pylori) infection has been implicated in a number of malignancies and non-malignant conditions including peptic ulcers, non-ulcer dyspepsia, recurrent peptic ulcer bleeding, unexplained iron deficiency anaemia, idiopathic thrombocytopaenia purpura, and colorectal adenomas. The confirmatory diagnosis of H pylori is by endoscopic biopsy, followed by histopathological examination using haemotoxylin and eosin (H & E) stain or special stains such as Giemsa stain and Warthin-Starry stain. Special stains are more accurate than H & E stain. There is significant uncertainty about the diagnostic accuracy of non-invasive tests for diagnosis of H pylori.

OBJECTIVES

To compare the diagnostic accuracy of urea breath test, serology, and stool antigen test, used alone or in combination, for diagnosis of H pylori infection in symptomatic and asymptomatic people, so that eradication therapy for H pylori can be started.

SEARCH METHODS

We searched MEDLINE, Embase, the Science Citation Index and the National Institute for Health Research Health Technology Assessment Database on 4 March 2016. We screened references in the included studies to identify additional studies. We also conducted citation searches of relevant studies, most recently on 4 December 2016. We did not restrict studies by language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We included diagnostic accuracy studies that evaluated at least one of the index tests (urea breath test using isotopes such as 13C or 14C, serology and stool antigen test) against the reference standard (histopathological examination using H & E stain, special stains or immunohistochemical stain) in people suspected of having H pylori infection.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the references to identify relevant studies and independently extracted data. We assessed the methodological quality of studies using the QUADAS-2 tool. We performed meta-analysis by using the hierarchical summary receiver operating characteristic (HSROC) model to estimate and compare SROC curves. Where appropriate, we used bivariate or univariate logistic regression models to estimate summary sensitivities and specificities.

MAIN RESULTS

We included 101 studies involving 11,003 participants, of which 5839 participants (53.1%) had H pylori infection. The prevalence of H pylori infection in the studies ranged from 15.2% to 94.7%, with a median prevalence of 53.7% (interquartile range 42.0% to 66.5%). Most of the studies (57%) included participants with dyspepsia and 53 studies excluded participants who recently had proton pump inhibitors or antibiotics.There was at least an unclear risk of bias or unclear applicability concern for each study.Of the 101 studies, 15 compared the accuracy of two index tests and two studies compared the accuracy of three index tests. Thirty-four studies (4242 participants) evaluated serology; 29 studies (2988 participants) evaluated stool antigen test; 34 studies (3139 participants) evaluated urea breath test-13C; 21 studies (1810 participants) evaluated urea breath test-14C; and two studies (127 participants) evaluated urea breath test but did not report the isotope used. The thresholds used to define test positivity and the staining techniques used for histopathological examination (reference standard) varied between studies. Due to sparse data for each threshold reported, it was not possible to identify the best threshold for each test.Using data from 99 studies in an indirect test comparison, there was statistical evidence of a difference in diagnostic accuracy between urea breath test-13C, urea breath test-14C, serology and stool antigen test (P = 0.024). The diagnostic odds ratios for urea breath test-13C, urea breath test-14C, serology, and stool antigen test were 153 (95% confidence interval (CI) 73.7 to 316), 105 (95% CI 74.0 to 150), 47.4 (95% CI 25.5 to 88.1) and 45.1 (95% CI 24.2 to 84.1). The sensitivity (95% CI) estimated at a fixed specificity of 0.90 (median from studies across the four tests), was 0.94 (95% CI 0.89 to 0.97) for urea breath test-13C, 0.92 (95% CI 0.89 to 0.94) for urea breath test-14C, 0.84 (95% CI 0.74 to 0.91) for serology, and 0.83 (95% CI 0.73 to 0.90) for stool antigen test. This implies that on average, given a specificity of 0.90 and prevalence of 53.7% (median specificity and prevalence in the studies), out of 1000 people tested for H pylori infection, there will be 46 false positives (people without H pylori infection who will be diagnosed as having H pylori infection). In this hypothetical cohort, urea breath test-13C, urea breath test-14C, serology, and stool antigen test will give 30 (95% CI 15 to 58), 42 (95% CI 30 to 58), 86 (95% CI 50 to 140), and 89 (95% CI 52 to 146) false negatives respectively (people with H pylori infection for whom the diagnosis of H pylori will be missed).Direct comparisons were based on few head-to-head studies. The ratios of diagnostic odds ratios (DORs) were 0.68 (95% CI 0.12 to 3.70; P = 0.56) for urea breath test-13C versus serology (seven studies), and 0.88 (95% CI 0.14 to 5.56; P = 0.84) for urea breath test-13C versus stool antigen test (seven studies). The 95% CIs of these estimates overlap with those of the ratios of DORs from the indirect comparison. Data were limited or unavailable for meta-analysis of other direct comparisons.

AUTHORS' CONCLUSIONS

In people without a history of gastrectomy and those who have not recently had antibiotics or proton ,pump inhibitors, urea breath tests had high diagnostic accuracy while serology and stool antigen tests were less accurate for diagnosis of Helicobacter pylori infection.This is based on an indirect test comparison (with potential for bias due to confounding), as evidence from direct comparisons was limited or unavailable. The thresholds used for these tests were highly variable and we were unable to identify specific thresholds that might be useful in clinical practice.We need further comparative studies of high methodological quality to obtain more reliable evidence of relative accuracy between the tests. Such studies should be conducted prospectively in a representative spectrum of participants and clearly reported to ensure low risk of bias. Most importantly, studies should prespecify and clearly report thresholds used, and should avoid inappropriate exclusions.

Bacterial urease and its role in long-lasting human diseases

Urease is a virulence factor found in various pathogenic bacteria. It is essential in colonization of a host organism and in maintenance of bacterial cells in tissues. Due to its enzymatic activity, urease has a toxic effect on human cells. The presence of ureolytic activity is an important marker of a number of bacterial infections. Urease is also an immunogenic protein and is recognized by antibodies present in human sera. The presence of such antibodies is connected with progress of several long-lasting diseases, like rheumatoid arthritis, atherosclerosis or urinary tract infections. In bacterial ureases, motives with a sequence and/or structure similar to human proteins may occur. This phenomenon, known as molecular mimicry, leads to the appearance of autoantibodies, which take part in host molecules destruction. Detection of antibodies-binding motives (epitopes) in bacterial proteins is a complex process. However, organic chemistry tools, such as synthetic peptide libraries, are helpful in both, epitope mapping as well as in serologic investigations.

In this review, we present a synthetic report on a molecular organization of bacterial ureases - genetic as well as structural. We characterize methods used in detecting urease and ureolytic activity, including techniques applied in disease diagnostic processes and in chemical synthesis of urease epitopes. The review also provides a summary of knowledge about a toxic effect of bacterial ureases on human body and about occurrence of anti-urease antibodies in long-lasting diseases.

Deprivation, timing of preschool infections and H. pylori seropositivity at age 49-51 years: the Newcastle Thousand Families birth cohort

Background

Helicobacter pylori infection is acquired in early childhood and persists for life (or until eradication treatment is taken). Seropositivity of H. pylori at age 49-51 years was assessed in relation to socio-economic deprivation in early life and the timing of other childhood infections common at that time.

Methods

Prospectively collected socio-economic and morbidity data from the Newcastle Thousand Families study, a birth cohort established in 1947. H. pylori IgG seropositivity was assessed at 49-51 years and examined in relation to both whether the individual had been diagnosed with one of measles, mumps or chicken pox, and, if so, the age at first infection. This was done in logistic regression models, allowing adjustment for socio-economic status and housing quality in childhood.

Results

Adult H. pylori status was strongly linked to disadvantaged socio-economic status in early life (p ≤ 0.002), unlike measles, mumps and chicken pox which showed no associations. Early measles infection was independently associated with H. pylori seropositivity (p = 0.01).

Conclusions

Of the four infectious diseases that we have studied, it appears that H. pylori differs from the others by the strength of association with socio economic deprivation in early childhood.

Our findings further highlight the complex interaction between measles, childhood infections and other non-microbiological factors that occur within a whole population. These data suggest a strong association between H. pylori and deprivation and raise the possibility of an interaction between early measles exposure and increased risk of exposure to H. pylori infection.

Meta-analysis: Helicobacter pylori eradication treatment efficacy in children

BACKGROUND

Several meta-analyses assessing the efficacy of anti-Helicobacter pylori treatment in adults have been published but a comparable meta-analysis in children is lacking.

AIMS

To summarize the efficacy of treatments aimed at eradicating H. pylori in children and to identify sources of variation in treatment efficacy across studies.

METHODS

We searched Medline, reference lists from published study reports, and conference proceedings for anti-H. pylori treatment trials in children. Weighted meta-regression models were used to find sources of variation in efficacy.

RESULTS

Eighty studies (127 treatment arms) with 4436 children were included. Overall, methodological quality of these studies was poor with small sample sizes and few randomized-controlled trials. The efficacy of therapies varied across treatment arms, treatment duration, method of post-treatment assessment and geographic location. Among the regimens tested, 2-6 weeks of nitroimidazole and amoxicillin, 1-2 weeks of clarithromycin, amoxicillin and a proton pump inhibitor, and 2 weeks of a macrolide, a nitroimidazole and a proton pump inhibitor or bismuth, amoxicillin and metronidazole were the most efficacious in developed countries.

CONCLUSIONS

Before worldwide treatment recommendations are given for eradication of H. pylori, additional well-designed randomized placebo-controlled paediatric trials are needed, especially in developing countries where both drug resistance and disease burden is high.

Human Milk Vacuolating Cytotoxin A Immunoglobulin A Antibodies ModifyHelicobacter pyloriInfection in Gambian Children

We collected data, including the weights, urea breath test results, and presence of maternal milk cytotoxin-associated gene-specific and vacuolating cytotoxin A-specific immunoglobulin A monthly from 48 mothers and infants (to 44 weeks of age) in The Gambia. In all, 11 children (23%) had negative urea breath test results, and 37 (77%) had positive results. Weight loss associated with Helicobacter pylori colonization was restricted to children whose mothers did not produce anti-vacuolating cytotoxin A antibodies in their milk (P=.028, by t test).

Does increased duration of exclusive breastfeeding protect against Helicobacter pylori Infection? The Newcastle Thousand Families Cohort Study at age 49-51 years

OBJECTIVE

Helicobacter pylori acquired in childhood is an important risk factor for gastric carcinoma. Once colonization is established, infection may be carried for life. This study used prospectively recorded, detailed information on infant feeding and investigated the potential link between duration of exclusive breastfeeding in infancy and seropositivity at age 50 years, as measured by enzyme-linked immunosorbent assay.

METHODS

H. pylori seropositivity at age 50 years was investigated among 407 individuals born in Newcastle in May and June 1947 and related to the duration of exclusive breastfeeding after adjusting for measures of socioeconomic status and adverse housing conditions at birth.

RESULTS

Duration of exclusive breastfeeding in infancy was significantly associated with H. pylori seropositivity (odds ratio per 30 days, 0.88; 95% confidence interval, 0.78 to 0.98). The significant protective trend was only seen among men (odds ratio per 30 days, 0.78; 95% confidence interval, 0.65 to 0.95), with no significant effect seen among women.

CONCLUSION

Increased duration of exclusive breastfeeding in infancy may have a long-term protective effect against chronic H. pylori infection and hence the risk of gastric carcinoma. Although further research is required, particularly as to why a significant effect was only seen among men, the results provide additional support for the concept that breastfeeding may have long-term influences on health and that human milk is the ideal complete first diet for human infants.

Tooth loss and Helicobacter pylori seropositivity: the Newcastle Thousand Families Cohort Study at age 49-51 years

BACKGROUND

Helicobacter pylori, one of the commonest chronic bacterial infections of humankind, is an important risk factor for gastric carcinoma. It has also been suggested to be present in dental plaque. This study investigated the potential link between the number of teeth lost and H. pylori seropositivity at age 50 years.

METHODS

H. pylori seropositivity at age 50 years was investigated among 334 individuals born in Newcastle upon Tyne, United Kingdom, in May and June 1947 and related to the number of teeth lost, after adjusting for socioeconomic status.

RESULTS

The unadjusted risk of being seropositive for H. pylori increased with increasing number of teeth lost (odds ratio per tooth 1.03, 95% confidence interval 1.01-1.06, p = .019). However, after adjustment for socioeconomic status at birth and at age 50 years, the relationship was no longer significant (p = .36).

CONCLUSIONS

Our results, obtained using prospectively collected data, suggest that any relationship between poor oral health and seropositivity to H. pylori may be due to both tooth loss and H. pylori colonization being associated with socioeconomic status and related factors.

Comparison of different criteria for interpretation of immunoglobulin G immunoblotting results for diagnosis of Helicobacter pylori infection

Gastric infection with Helicobacter pylori is one of the most common chronic infections in humans, causing substantial morbidity and mortality. The diagnosis of H. pylori infection usually involves upper endoscopy with biopsy since the only noninvasive method of comparable accuracy, the [(13)C]urea breath test, requires technical equipment that is not available in most gastroenterological units. Serological methods for detection of H. pylori infection have reached sufficient accuracy to be used as screening tests before endoscopy or for seroepidemiological surveys. In the present study we evaluated different interpretation criteria for use with immunoglobulin G immunoblotting for the diagnosis of H. pylori infection. We applied five different sets of interpretation criteria, four of which had been published previously, to the Western blot results of 294 patients with different gastrointestinal symptoms. Since it is known that less than 2% of patients who are infected with H. pylori fail to seroconvert, an optimally sensitive Western blotting system should be able to detect approximately 98% of active infections. When the different criteria were applied to our patient population, it became apparent that the abilities of the systems to detect active H. pylori infection were quite varied. The results for the sensitivity and specificity, according to the different applied criteria, ranged from 62.8 to 95.9% and from 85.7 to 100.0%, respectively. Positive predictive values and negative predictive values, according to the published criteria, ranged from 97.2 to 100.0% and from 37.7 to 82.4%, respectively. Recommendations for the optimal use of the different interpretation criteria are discussed.

Specific Immunoglobulin A Antibodies in Maternal Milk and Delayed Helicobacter pylori Colonization in Gambian Infants

BACKGROUND

Immunoglobulin A (IgA) in maternal milk may protect Gambian infants from early Helicobacter pylori colonization. This study sought evidence that this protection could be due to specific IgA antibodies.

METHODS

Sixty-five infants were screened from 12 weeks of age with [13C]-urea breath tests. Antibodies in maternal milk were measured to determine total IgA content and to detect specific IgA antibodies against crude whole-cell and recombinant H. pylori urease antigen preparations.

RESULTS

Ten children (15%) had no evidence of early H. pylori colonization, 10 (15%) had early H. pylori colonization, and 43 (66%) had mixed results. Levels of maternal circulating specific immunoglobulin G, total milk IgA, and IgA directed against crude whole-cell H. pylori antigen preparation were not significantly associated with the rate of infant H. pylori colonization. However, mothers of infants with no evidence of early colonization produced significantly higher levels of anti-recombinant urease IgA antibodies in milk than did control mothers, particularly at 8, 16, and 20 weeks postpartum (P<.01).

CONCLUSIONS

These observations support the hypothesis that antibodies in mother's milk directed against H. pylori urease can protect against colonization in human infancy.

IgG subclass responses in childhood Helicobacter pylori duodenal ulcer: evidence of T-helper cell type 2 responses

BACKGROUND

Duodenal ulcer in adults chronically infected with Helicobacter pylori is associated with a polarized T-helper cell type 1 (Th1) mucosal immune response, with a predominantly immunoglobulin G2 (IgG2) systemic specific response. It has been suggested that children colonized by H. pylori also produce a mucosal Th1 response, but there are few studies that have measured IgG subclass responses in children with duodenal ulcer.

MATERIALS AND METHODS

Seven children with endoscopically proven duodenal ulcer and H. pylori infection and 18 children with biopsy proven H. pylori infection but no duodenal ulcer had relative concentrations of IgG subclass responses (IgGsc) against H. pylori antigens measured by ELISA. Eighteen IgG seropositive adults acted as controls. The range of antigens recognised by IgG1 and IgG2 subclass responses were investigated by Western blots.

RESULTS

There were no differences in mean IgGsc responses between children with or without duodenal ulcer. Adults produced an IgG2 predominant response. Western blots showed no qualitative differences in antigens recognised by IgG1 or IgG2.

CONCLUSION

Children with duodenal ulcer, in contrast to adults, produce an IgGsc response consistent with a mucosal Th2 response to H. pylori regardless of the presence of duodenal ulceration. This suggests that disease causation amongst children with H. pylori associated duodenal ulceration may not be dependant upon a mucosal Th1 biased response.

Seroprevalence of Helicobacter pylori in school-aged Chinese in Taipei City and relationship between ABO blood groups

AIM: To explore the seropositive rate of antibodies against H. pylori (anti-HP) in Taipei City and to compare the relationship of ABO blood groups and H. pylori infection.

METHODS: In 1993, high school students in Shih-Lin District were randomly selected for blood samplings by their registration number at school. In addition, similar procedures were performed on the well-children clinics of Taipei Veterans General Hospital. Besides, randomly selected sera from the adults who took the physical examination were recruited for evaluation. Informed consents were obtained from all the subjects before blood samplings and parents were simultaneously informed for those who were younger than 18-year-old. Blood tests for anti-HP and ABO blood groupings were performed by enzyme-linked immunosorbent assay. Chi square tests were used for the comparisons between seroprevalence of H. pylori and ABO blood groups.

RESULTS: Totally, 685 subjects were recruited (260 children aged 1-14 years, 425 high school students aged 15-18 years) were evaluated, and another 88 adult healthy volunteers were studied as well for comparison. The age-specific seropositive rate of anti-HP was 1.3% at age 1-5 years, 7.7% at age 6-10 years, and 11.5% at age 11-14 years. The seroprevalence of H. pylori infection was abruptly increased in young adolescence: 18.6% at age 15 years, 28.1% at age 16 years, 32.4% at age 17 years and 41.0% at age 18 years, respectively. In the 425 high school students, ABO blood groupings were performed, which disclosed 48.5% (206/425) of blood group O, 24% (102/425) of blood group A, 21.8% (93/425) of blood group B and 5.6% (24/425) of blood group AB. In comparison of the subjects with blood group O and the other blood groups, no statistical significance could be identified in the seroprevalence of H. pylori (P = 0.99).

CONCLUSION: The seroprevalence of H. pylori infection in Taipei City in adults is similar to the developed countries, and the abrupt increase of H. pylori during high school may be resulted from marked increase of interpersonal social activities. Although blood group O was reported to be related to H. pylori infection in previous literature, we found no association between H. pylori infection and ABO blood groups.

Serologic prevalence of antibodies to Helicobacter pylori in internationally adopted children

BACKGROUND

Helicobacter pylori (H. pylori) infection has been linked to gastritis, diarrhea, peptic ulcers, failure-to-thrive, anemia, as well as predisposition to gastric malignancies. Because many internationally adopted children have diarrhea, failure-to-thrive, and anemia on arrival to the US, we determined the prevalence of HP antibodies among these children.

METHODS

Serum samples from 226 unselected children from 18 countries who were evaluated in the International Adoption Clinic at New England Medical Center were tested for antibodies to H. pylori. The results of serologic screening were analyzed in relation to age at adoption, site of residence prior to adoption, weight and height, and the presence or absence of anemia, diarrhea, or intestinal parasites.

RESULTS

31% of internationally adopted children had antibodies to H. pylori. The presence of H. pylori-antibodies was associated with residence in an orphanage (vs. foster care) prior to adoption, older age at adoption, and coinfection with intestinal parasites. No direct effects on height or weight were identified; no associations with diarrhea or anemia were found.

CONCLUSIONS

Internationally adopted children have a high incidence of exposure to H. pylori, as diagnosed serologically. Residence in an orphanage (compared with foster care), older age at adoption, and coinfection with intestinal parasites were more common among children seropositive for anti-H. pylori antibodies.

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

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

Helicobacter pylori seropositivity in children with atopic dermatitis as sole manifestation of food allergy

A positive association between Helicobacter pylori antibodies and food allergy presenting with gastrointestinal symptoms has recently been reported. A subset of a H. pylori strain possesses an antigen, CagA, as a virulence factor. Anti-H. pylori and anti-CagA IgG titre have been determined in children with atopic dermatitis (AD) as the sole clinical manifestation of food allergy. In this study, thirty patients with AD as the sole clinical manifestation of food allergy were examined (group A). For comparative purposes, 30 patients affected by food allergy with gastrointestinal symptoms (group B) and 30 affected by atopic asthma (group C) were studied. Anti-H. pylori and anti-CagA immunoglobulin G (IgG) were determined in all individuals by means of the enzyme-linked immunosorbent assay. The anti-H. pylori IgG titre was significantly higher in group A and group B vs. group C (p < 0.05); no significant difference was detected between group A and group B (p > 0.05). No significant difference in anti-CagA titre was found between the groups. These data demonstrate a positive association between H. pylori antibodies and AD as the sole manifestation of food allergy. Further investigations are needed to evaluate the cause-effect relationship between H. pylori seropositivity and AD.

Influence of Helicobacter pylori infection on the phenotype of Crohn's disease

OBJECTIVE

Very little is known about the impact of Helicobacter pylori (H. pylori) infection on Crohn's disease. In this study we investigated a possible influence of H. pylori on the phenotype of Crohn's disease.

METHODS

Patients with Crohn's disease who had gastric biopsy between 1990 and 1994 and a clinical follow-up in our outpatient clinic for at least 2 yr were included in the study. The mean number of flare-ups per year of follow-up, the mean numbers of intestinal resections per year of disease duration, and primary disease location were compared in H. pylori-positive and -negative patients. Various regression models were calculated to test the influence of H. pylori status on these parameters, correcting for smoking habits and disease duration.

RESULTS

Of 131 patients, 50 (38.2%) were H. pylori positive and 62 (47.3%) were smokers. Due to a significant interaction between smoking habits and H. pylori infection, regression models were calculated separately for smokers and nonsmokers. Nonsmokers without H. pylori infection had more flare-ups than nonsmokers with H. pylori infection (0.77 [0.57-0.97] vs 0.29 [0.16-0.42]; p < 0.01; mean [95% confidence interval]). In contrast, nonsmokers without H. pylori infection had less intestinal resections than nonsmokers infected with H. pylori (0.08 [0.04-0.12] vs 0.11 [0.07-0.15]; p < 0.05). These differences were not significant for smokers (p < 0.41 and p < 0.07). There was a predominance of small bowel disease in H. pylori-positive patients, which did not reach statistical significance.

CONCLUSIONS

Our data indicate that H. pylori influences the phenotype of Crohn's disease, especially in nonsmokers.

Detection of Helicobacter pylori antibodies in a pediatric population: comparison of three commercially available serological tests and one in-house enzyme immunoassay

A serum immunoglobulin G enzyme immunoassay (EIA) for Helicobacter pylori antibodies already in use in adults was evaluated with 99 pediatric serum samples to determine its usefulness for the study of H. pylori disease in children. The reference method used was either the (13)C-urea breath test or a biopsy culture of gastric mucosa. In children, an EIA cutoff of 0.35 absorbancy unit yielded sensitivity, specificity, and positive and negative predictive values of 93, 97, 93, and 97%, respectively. The cutoff recommended when this EIA was published for use in adults was 0.70 absorbancy unit (H. Gnarpe, P. Unge, C. Blomqvist, and S. Mäkitalo, APMIS 96:128-132, 1988). Another subset of 169 serum samples taken from children was analyzed by four serological tests in order to compare the performance of the in-house EIA with the Pyloriset, HM-CAP, and Helico-G kits. For the 169 samples, 10 (5.9%) false-positives and no false-negatives occurred with the Helico-G, 3 (1.8%) false-positives and no false-negatives occurred with the Pyloriset, and 3 (1.8%) false-positives and 1 (0.6%) false-negative occurred with the HM-CAP. For the 169 samples, 1 (0.6%) false-positive and no false-negatives occurred with the in-house EIA. Serological detection of H. pylori antibodies with our EIA seems to be valuable in diagnosing H. pylori infection in children, but only if a lowered, specific pediatric cutoff is established. The commercial kits, particularly the Helico-G, seem to overdiagnose pediatric H. pylori infection. A positive serological test for H. pylori infection, particularly for children, needs to be confirmed by a reference method because of the possibility of spontaneous eradication of infection, with a lingering serological response.

Gastric inflammation is enhanced in children with CagA-positive Helicobacter pylori infection

BACKGROUND

Helicobacter pylori infection is likely to be acquired at an early age. The factors leading to active inflammation in childhood, however, are largely unknown.

SUBJECTS AND METHODS

We determined the CagA status, the best characterized virulence factor of H. pylori, and serum antibodies of IgG and IgA classes to H. pylori in 39 infected children.

RESULTS

Mononuclear cell infiltration in the antrum but not in the gastric body was more intense in CagA-positive children than in CagA-negative children. The degree of polymorphonuclear cell infiltration on the other hand was independent of the CagA status. The antibody titers of IgG and IgA classes to H. pylori were higher in CagA-positive than in CagA-negative infections (P<0.001 and P<0.01, respectively). IgG antibody titers to H. pylori correlated directly with the density of mononuclear and polymorphonuclear cell infiltration in the gastric antrum but not in the gastric body.

CONCLUSION

H. pylori-infected children with CagA antibodies seem to have a more severe inflammation in the gastric antrum than CagA-negative children as shown by an increase in the density of antral mononuclear cells. A finding of higher serum antibody titers to H. pylori in CagA-positive children may be related to this enhancement of inflammation.

Evaluation of enzyme-linked immunosorbent assay for the diagnosis of Helicobacter pylori infection in children from different age groups with and without duodenal ulcer

BACKGROUND

Although enzyme-linked immunosorbent assay (ELISA) is highly sensitive and specific for the diagnosis of Helicobacter pylori infection in adults, their performance in children is still controversial.

METHODS

A second-generation ELISA was used to evaluate the IgG response to H. pylori in the serum of 130 consecutive children who underwent upper gastrointestinal endoscopy. The presence of H. pylori was determined in antral biopsy specimens by culture, urease test, and histologic analysis.

RESULTS

Sixty-eight children (all of the 20 who had duodenal ulcer) were H. pylori positive by microbiologic test. Immunoglobulin G antibodies to H. pylori were detected in 79.4% of the infected children and in 8.1% of the noninfected ones. The sensitivity of the test was higher in patients with duodenal ulcer (100%) than in those without (70.8%). When used in children of different ages the test also presented differences in sensitivity: 44.4% in children 2 to 6 years old; 76.7% in children 7 to 11 years old, and 93.1% in children 12 to 16 years old (p = 0.006). The serum immunoglobulin G concentration was significantly higher (p = 0.0003) in children with duodenal ulcer than in those without and was higher in older children than in younger ones without duodenal ulcer (p = 0.05).

CONCLUSIONS

The accuracy of the test in children with duodenal ulcer and in children more than 12 years old was good; however, in children up to 12 years of age without duodenal ulcer, the sensitivity of the test was too low to be used for screening purposes or to rule out the presence of infection.

Helicobacter pylori colonization in early life

Helicobacter pylori infection is a major cause of upper gastrointestinal disease throughout the world. Colonization begins in childhood, although little is known about its age of onset, rate, or mode of colonization. Our aim was to identify the age of acquisition of H. pylori colonization in Gambian children. A cohort of 248 Gambian children aged 3 to 45 months was studied at intervals of 3 months for 2 years, using the 13C-urea breath test, specific IgM and specific IgG serology. The prevalence of positive breath tests rose from 19% at 3 months of age to 84% by age 30 months. Elevated specific IgG and IgM antibody levels were associated with positive breath tests, although there was discrepancy between breath test results and serology, particularly IgG serology, during the 1st year of life. Neither IgG nor IgM serology could be validated as reliable diagnostic tools for infant H. pylori colonization compared with the 13C-urea breath test. Reversion to negative breath test, in association with declining specific antibody levels, occurred in 48/248 (20%) of children. On the assumption that the 13C-urea breath test is a reliable index of H. pylori colonization, we conclude that the infection is extremely common from an early age in Gambian children. Transient colonization may occur. Previous studies relying on serodiagnosis may have significantly underestimated the true early prevalence of colonization in the developing world, where the target age for intervention studies is probably early infancy.

Diagnosis of Helicobacter pylori

In view of its potential risk for the development of gastrointestinal disease or even gastric cancer at a later age, the study of Helicobacter pylori infection in childhood is gaining increasing importance and H. pylori infection is being considered a major issue of public health. H. pylori infection can be detected by a variety of methods. Because of its easy use, affordability, and overall availability, serology is the preferred diagnostic test, especially for large epidemiological studies. Based on our results, one might consider treating a child with recurrent abdominal pain and positive serology for H. pylori without further work-up, and only perform additional investigations when an anti-H. pylori therapy fails to resolve the complaints. According to this proposition, endoscopy of the upper gastrointestinal tract remains indicated in children if the noninvasive tests for Helicobacter pylori are negative in the absence of a diagnosis, or if symptomatology persists despite treatment.

Prevalence of Helicobacter pylori antibodies in children in Bloemfontein, South Africa

BACKGROUND

An association of H. pylori infection with chronic gastritis, peptic ulceration and gastric cancer is known.

METHODS

Prevalence of IgG antibodies to Helicobacter pylori in children in the Bloemfontein, South Africa area was studied. Children attending the general pediatric outpatient department at Pelonomi Hospital in Bloemfontein were grouped according to age. A minimum of 100 children was investigated in each age group. Baseline demographic and socioeconomic data were collected.

RESULTS

The study showed a high prevalence of H. pylori antibodies. Prevalence increased with age: 13.5% in children 3 months-2 years, 48.5% at 2-5 years, 67.3% at 5-10 years and 84.2% at 10-15 years. Investigation of the socioeconomic data in relation to the prevalence of H. pylori was inconclusive.

CONCLUSIONS

This high prevalence needs further study.

Evaluation of a serological test for diagnosis of Helicobacter pylori infection in children

A serological test for the diagnosis of Helicobacter pylori infection (Cobas Core Roche, IgG, 2nd Generation; Roche, France) was compared with the examination of biopsy samples (culture and histology) obtained after endoscopy in 115 children to assess its value. In 94 children (42 positive and 52 negative), results were concordant. In 10 children a positive serological test was associated with an absence of Helicobacter pylori, while in 11 others a negative serological test was associated with a positive culture. Sensitivity of the test was 79.2% and specificity 83.9%. A relationship between IgG titers and age (r = 0.31, p < 0.05) was found. Serological tests could be useful for the diagnosis of Helicobacter pylori infection, but a negative test result does not rule out infection, particularly in children under 10 years of age.

Presentation and management of Helicobacter pylori infection in childhood

Helicobacter pylori is responsible for one of the most frequently encountered infectious diseases worldwide. Helicobacter pylori infection can lead to the development of gastritis and peptic ulcer disease. The presence of Helicobacter pylori in the human stomach also represents an increased risk of gastric cancer and gastric lymphoma. Epidemiological data obtained in adults suggest that the actual colonization with Helicobacter pylori is in fact determined by childhood factors. Therefore, the pediatric age group represents the ideal target population for studies concerning the pathogenesis and epidemiology of Helicobacter pylori infection. The present work reflects our experience with regard to the diagnosis, epidemiology and pathogenesis of Helicobacter pylori infection in childhood.

Helicobacter pylori disease in childhood

Helicobacter pylori (H. pylori) is responsible for one of the most frequently encountered infectious diseases worldwide. H. pylori infection can lead to the development of gastritis and peptic ulcer disease. The presence of H. pylori in the human stomach also represents an increased risk for gastric cancer and gastric lymphoma. Epidemiologic data obtained in adults suggest that the actual colonization with H. pylori is in fact determined by childhood factors. Therefore, the pediatric age group represents the ideal target population for studies concerning the pathogenesis and epidemiology of H. pylori infection.

Helicobacter pylori and peptic disease in the pediatric patient

The data accumulated on Helicobacter pylori infection in children suggests an important causative role of the organism in gastritis and peptic ulcer disease in this age group. The importance of eradication of H pylori in asymptomatic children in relation to its role in peptic disease and cancer in adults is debatable. This article describes the current data on bacteriologic features, pathologic spectrum, clinical significance, epidemiology, methods of diagnosis, and treatment of H pylori infection in children. Further studies will provide the information on the pathogenicity, mode of transfer, and optimal treatment of H pylori infection.

Consideration of Helicobacter pylori infection in childhood: immune response, endoscopic and morphological findings

Seventy-five children (aged 9-14 years) infected with Helicobacter pylori were studied endoscopically and morphologically for the signs of infection and immune response by ELISA technique (total IgE and specific IgG against H. pylori); a control group of 36 children (not infected with H. pylori) were studied simultaneously. Helicobacter pylori positive children examined endoscopically revealed a number of mucous membrane changes including erythema, erosions, lymphoid nodular hyperplasia and ulcers. Gastritis was confirmed by histology in 58 children; 6% were termed 'active', others were 'non-active'. When studying the concentrations of anti-H. pylori IgG in children from the control group they were considered to be seronegative but in children infected with H. pylori a considerable increase was noted. An evaluation of the interaction between anti-H. pylori IgG titers and age, endoscopic signs and histology was carried out. Suppositions were made about the presence of links between these characteristics. Children with H. pylori infection showed a considerable increase of total IgE titers in comparison with the control group. The role of IgG and IgE in the development of chronic gastroduodenal diseases associated with H. pylori is discussed.

Oxidative metabolism in nonculturable Helicobacter pylori and Vibrio vulnificus cells studied by substrate-enhanced tetrazolium reduction and digital image processing

Growing and nonculturable cells of Helicobacter pylori and Vibrio vulnificus were studied for the capacity to reduce tetrazolium salts in order to elucidate the possible physiological basis for the proposed "viable but nonculturable" (VNC) state. Initial difficulties in obtaining consistent reduction of rho-iodonitrotetrazolium violet (INT) by H. pylori led us to develop a method for studying the effect of adding exogenous substrates on these reactions. The established procedure provided a profile of substrate enhancement of oxidative activity revealed by INT reduction which was related to both the identity and physiological state of the organism studied. Representation and interpretation of these enhancement profiles were facilitated by digital image processing. Nonculturable cells of H. pylori produced by carbon and nitrogen starvation in air lost all INT-reducing capacity in 24 h when stored at 37 degrees C, while 99% of those produced at 4 degrees C retained oxidative activity for at least 250 days when tested in the presence but not in the absence of succinate, alpha-ketoglutarate, or aspartate. Activity was detected at similar levels in cells with coccoid and spiral shapes. In contrast, only 1% of nonculturable cells of V. vulnificus, produced under conditions previously reported to induce the VNC state in this organism, retained intrinsic INT-reducing capacity; no substrate-enhanced activity occurred in the remainder of the population. Thus, there was no common pattern of oxidative activity indicative of a VNC state in both test organisms. Nonculturable cells of H. pylori can retain several different oxidative enzyme activities; whether these indicate viability or the persistence of cells as "bags of enzymes" remains to be established.

The role of serology in the diagnosis of Helicobacter pylori infection in children

The aim of this study was to evaluate the diagnostic accuracy of serologic tests and to verify whether specific IgG antibody can be used in the diagnosis of Helicobacter pylori infection in children without endoscopy. Serologic and endoscopic examinations were performed in 310 children (1 month-15 years) with gastrointestinal symptoms. Serologic outcomes were compared with the results of rapid urease test, histologic examination, and culture. The prevalence of H. pylori infection was 21.0% and the seropositivity of H. pylori was 24.2% in these symptomatic children. Serologic examination for diagnosis of H. pylori showed a sensitivity of 94.9% and a specificity of 92.4%, diagnostic reliability equal to the rapid urease test and histologic examination in children. The serum IgG test is a useful tool for the diagnosis of H. pylori infection, especially in children.

Helicobacter pylori in endoscopy patients in Zimbabwe: value of enzyme-linked immunosorbent assay and a rapid urease test

Biopsy and serum specimens were obtained from 95 patients undergoing endoscopy at the University of Zimbabwe Medical School. Common presenting features were epigastric pain, bleeding and dyspepsia. Ulcers were detected in 16 patients (17%), and were more common in men (24%) than in women (7%). Histological examination of biopsies showed that all 95 patients had spiral-shaped organisms that were indistinguishable microscopically from Helicobacter pylori, though the numbers of organisms varied considerably. There was evidence that the degree of inflammation in the mucosa was related to the numbers of H. pylori-like organisms (HPLO) present. Fifty-one biopsy specimens (55%) gave a positive rapid urease test (RUT), with colour change occurring within 4 h. In all but one case, the gastric mucosa from these patients contained moderate to numerous HPLO. We defined the 'gold standard' of H. pylori-associated gastritis as the presence of both moderate to numerous HPLO and moderate to severe inflammation in the gastric mucosa. Using these criteria, RUT had a sensitivity of 67% and a specificity of 68%. Sera from 92 patients were tested for immunoglobulin G antibodies reactive with a glycine-extract antigen of H. pylori, using an enzyme-linked immunosorbent assay (ELISA). Sera giving an indeterminate reaction in the ELISA were also tested by Western blotting. In all, 36 sera (39%) gave a positive ELISA or Western blot reaction. There was poor correlation between serology and RUT results, with only 57% of biopsy specimens from seropositive patients giving a positive RUT, compared with 45% from seronegative patients. Positive serology was found in only 35 patients (61%) with histological evidence of H. pylori-associated gastritis, and the specificity of the test was only 54%. When used in combination with the RUT result, however, 79% of patients with a positive RUT and positive serology had histological evidence of H. pylori-associated gastritis. There was a general trend for increased seroprevalence in patients with mild to moderate atypia. These findings indicate that serology, using an antigen derived from the type strain of H. pylori, is unreliable in detecting H. pylori infection in Zimbabwe. Current studies are aimed at characterizing antigens from organisms isolated from Zimbabwean patients.

Helicobacter pylori in children

Helicobacter pylori is the major cause of antral gastritis in children, however, it is not always associated with symptoms. The exception to this occurs in duodenal ulcer disease with which H. pylori is linked in children albeit less strongly than in adults. Duodenal ulcers do not recur in older children following eradication of H. pylori. The importance of asymptomatic carriage of H. pylori in children, particularly in relation to the duration of this infection and the subsequent development of gastric cancer, remain to be established. Helicobacter pylori is associated with both hypochlorhydria and persistent diarrhoea in children in developing countries, but the significance of this association is still unknown. Although there is no consensus on the optimal regimen for treating H. pylori infection in children, dual therapy with amoxycillin and bismuth subcitrate for 2 weeks followed by monotherapy with bismuth subcitrate for a further 6 weeks will eradicate H. pylori infection in the majority of children. Those who relapse may be treated with a repeat course plus metronidazole for 4 weeks. Compliance with such regimens is a problem and shorter treatment courses that are equally effective in children need to be defined. Similarly, studies are required on the influence of the intrafamilial reservoir of H. pylori infection on relapse after treatment and the need for whole family eradication therapy.

Royal Society of Tropical Medicine and Hygiene Meeting at Manson House, London, 16 February 1995. Aspects of Helicobacter pylori infection in the developing and developed world. Helicobacter pylori infection, nutrition and growth of West African infants

Helicobacter pylori is probably the commonest bacterial infection of humankind. In adults, colonization of the stomach is associated with chronic gastritis and duodenal ulcer disease. However, children in the developing world acquire H. pylori soon after birth, and there is evidence that it plays a part, through suppression of the gastric acid barrier, in the pathogenesis of the syndrome of diarrhoea, malnutrition and growth failure. Infants born of mothers who secrete milk with high levels of anti-H. pylori immunoglobulin A (IgA) antibody acquire the infection later than those born of mothers with low specific antibody levels. Enhancement of maternal breast milk anti-H. pylori IgA levels may protect infants from H. pylori infection during the vulnerable weaning period when many are susceptible to enteric infections, leading to recurrent diarrhoea and adverse consequences on nutrition and growth.

Use of a receiver operating characteristic in the evaluation of two commercial enzyme immunoassays for detection of Helicobacter pylori infection

Two novel commercial IgG enzyme immunoassay (EIA) systems based on acid-glycine-extracted (Pyloriset IgG EIA, Orion Diagnostica) or fast protein liquid chromatography-purified (Cobas Core Anti-H. pylori EIA, Roche Diagnostic Systems) Helicobacter antigens were evaluated in a prospective study involving 127 patients. All patients underwent upper endoscopy with biopsy, and biopsies were examined for the presence of Helicobacter pylori by a rapid urease test, microscopy and culture. Of the 71 patients found to be infected with Helicobacter pylori, 69 (97.2%) and 65 (91.5%) tested positive with the Cobas Core and Pyloriset test, respectively. A detailed receiver operating characteristic analysis of the two tests showed that the Cobas Core assay was more sensitive and specific at every possible cut-off level; gave a better resolution of individual results, indicating a greater fine-sensitivity; and had no grey zone compared to a large grey zone encompassing 13.4% of the serum samples tested with the Pyloriset EIA. The Cobas Core assay appears to be a valuable tool for epidemiological purposes as well as for pre-endoscopic screening of dyspeptic patients.

Serum antibody response to the superficial and released components of Helicobacter pylori

Superficial and released components were extracted from six selected Helicobacter pylori strains. The protein and antigenic profiles of these extracts were representative of the profiles found most frequently among the clinical strains and included major peptidic fractions at 19, 23.5, 57, 68, 76, 118, and 132 kDa and major antigens at 68, 57, and 23.5 kDa. Immuno-cross-reactions were seen with a hyperimmune rabbit serum to Campylobacter fetus but not with sera to Campylobacter jejuni or Salmonella spp. An antigenic preparation was obtained by pooling equivalent quantities of each extract, and the antigenic preparation was used to study the antibody responses of sera from 65 French patients and 127 Tunisian patients. By enzyme-linked immunosorbent assay, we observed that the sera from French and Tunisian patients clustered into two populations, defined as antibody positive (72 patients) and antibody negative (120 patients). The antibody-positive patients were more frequently infected with H. pylori (P < 0.01) and were more frequently affected with gastritis (P = 0.05). However, no correlation between antibody levels and clinical signs of dyspepsia was noticed. The proportions of antibody-positive patients were similar in France and Tunisia. Antibody-positive and antibody-negative sera were studied by western blot (immunoblot) analysis. The antibody-positive sera revealed an average of 7.7 antigenic bands, whereas the antibody-negative sera revealed an average of 2.4 antigenic bands (P < 0.01). The antigens between 15 and 40 kDa and greater than 66 kDa were specifically recognized by the antibody-positive sera, although in this molecular size range the antibody profiles of these sera exhibited a fairly high degree of diversity. We conclude that the superficial and released components from H. pylori contain a variety of bacterial immunogens and may be useful in antigenic preparations for the serodiagnosis of H. pylori infections. Moreover, a group of antigens in combination appears to be useful for discriminating antibody-positive and antibody-negative patients.

Serological detection of Helicobacter pylori antibodies in children and their parents

The antibody response to Helicobacter pylori was examined in 56 children (ages 5 to 18) to determine whether serological tests can be used for diagnosis. Twenty-four children (43%) were H. pylori positive and 32 children (57%) were H. pylori negative by culture and histological examination of endoscopic biopsy specimens. The immune response was also examined in 39 nonendoscoped parents of the children. H. pylori-specific immunoglobulin G (IgG) and IgA antibodies were detected by the flow microsphere immunofluorescent assay (FMIA). IgG was also detected by using the Pyloristat enzyme-linked immunosorbent assay (ELISA). The sensitivity, specificity, and positive and negative predictive values for the FMIA for IgG were 100, 97, 96, and 100%, respectively. The respective values for the Pyloristat ELISA for IgG were 96, 94, 92, and 97%. The respective values for the FMIA for IgA were 50, 100, 100, and 73%. Both assays identified the same 19 parents as IgG positive, while FMIA identified 17 of the 19 parents as IgA positive.

High prevalence of Helicobacter pylori infection in cohabiting children. Epidemiology of a cluster, with special emphasis on molecular typing

Intrafamilial cases of infection with the same strain of Helicobacter pylori (H pylori) have been reported but these clusters were too small to distinguish between person to person spread or coinfection from a common environmental source. To gain more information on the mode of transmission of H pylori, an epidemiological survey with bacterial strain differentiation by restriction endonuclease analysis of chromosomal DNA was carried out in an institution of 117 children with encephalopathy (aged 3.5 to 19 years). All children with antibodies against H pylori had gastroscopy to obtain gastric biopsy specimens. The prevalence of infection (confirmed histologically or microbiologically, or both) was 38% (45/117), and rose to 67% in one of the five sections of the institution. H pylori was isolated in 34/45 cases, and 22 different strains were found of which five strains were present in more than one child. Up to seven children were infected by the same strain, five of them were living in the same section. Analysis of the characteristics of infected children showed the predominant role of living conditions and the period of time cohabiting in this unexpectedly high prevalence of H pylori infection in children living in good sanitary conditions.

Isolation of Helicobacter pylori from human faeces

Helicobacter pylori is arguably the commonest chronic infection in man. However, its route of transmission is unknown. We have isolated viable H pylori from the faeces of an infected individual from The Gambia. The organism was cultured on selective media after concentration of faecal bacteria by centrifugation in a buffer equilibrated with a microaerophilic gas mixture. Growth characteristics, microscopic appearances, and enzyme activities were the same as those of a typical gastric isolate of H pylori. Protein preparations derived from the new isolate and the typical strain were antigenically similar, and had very similar electrophoretic profiles (including two major protein bands of 62 and 26 kDa, corresponding to the urease enzyme subunits). With the same technique, organisms with the colony morphology, growth requirements, enzyme activities, and microscopic appearances of H pylori were isolated from the faeces of 9 of 23 randomly selected children aged 3-27 months from a Gambian village with a high prevalence of H pylori infection in early life. Faecal-oral transmission is probably important in the spread of infection in such communities.

Assay of urease-inhibiting activity in serum from children infected with Helicobacter pylori

In order to provide a basis for obtaining further information concerning the host response to Helicobacter pylori urease, four assay methods for detecting urease-inhibiting activity in serum were examined. A quantitative assay, established in a COBAS BIO centrifugal fast analyzer and based on detection of the consumption of NADH by glutamate dehydrogenase stimulated by ammonia production, was considered most suitable for large-scale serological work. Serum samples from 63 children (aged 5 to 16 years), 28 of whom had seropositive H. pylori gastritis, were assayed. One of the serum samples in this latter group showed significant inhibitory activity. This serum sample was one of 13 in the seropositive group known to bind to urease antigen. It showed no inhibitory activity against Bacillus pasteurii or jack bean urease. Protein A binding and heat treatment indicated that the inhibitory activity was immunoglobulin G mediated. The patient from whom this sample was collected showed no distinctive features in his illness. The COBAS BIO analyzer-based urease inhibition assay provides a new tool for studying one aspect of the host response to H. pylori infection.