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

Assessment of p21, p53 expression, and Ki-67 proliferative activities in the gastric mucosa of children with Helicobacter pylori gastritis

BACKGROUND

Helicobacter pylori that is generally acquired in childhood and infects the gastric mucosa is considered to be responsible for many pathobiological changes that are linked to the pathogenesis of gastric cancer. Although the majority of studies on the subject have been carried out in adults, there are a limited number of studies on children that reflect the early period of infection and may be of greater significance.

AIM

We aimed to determine the role of H. pylori infection and/or gastritis in several histopathological changes, p53, p21, and cell proliferation-associated Ki-67 antigen expression in the gastric mucosa.

MATERIALS AND METHODS

We studied 60 patients with a mean age of 7.5 ± 4.5 years at referral. On the basis of endoscopic appearance and the evaluation of the gastric antral specimens, the patients were divided into three groups: patients without gastritis, patients with H. pylori-positive gastritis, and patients with H. pylori-negative gastritis. To determine the expression of p53, Ki-67, and p21 in gastric biopsy specimens, immunohistochemical stains were performed.

RESULTS

The incidence of neutrophil activity, which was one of our histopathologic parameters, was significantly higher in the H. pylori-positive gastritis group than the other two groups. The presence of lymphoid aggregate was more frequent in H. pylori ± gastritis groups than the nongastritis group. p53 expression was found to be significantly higher in the H. pylori-positive gastritis group than the nongastritis group. Ki-67 and p21 expressions were significantly more frequent in the H. pylori-positive gastritis group than the other two groups. When we evaluated the density of H. pylori, as the density of bacteria increases, we found that the expressions of p53, p21, and Ki-67 increased significantly.

CONCLUSION

Expression of the studied precancerous markers in significant amounts indicates the importance of childhood H. pylori infection in the constitution of gastric cancer in adulthood.

A rapid serologic test and immunoblotting for the detection of Helicobacter pylori infection in children

The gold standard for the diagnosis of Helicobacter pylori infection requires an endoscopic biopsy of gastric mucosa for histological examination, urease test and culture. Noninvasive serological tests are useful as a screening test for H. pylori infection. The aim of this study was to evaluate the performance of a rapid office-based serologic test, using immunochromatography ICM, and the immunoblotting for the diagnosis of H. pylori infection in Thai children. Eighty-two symptomatic children, 30 boys and 52 girls (mean age 9.2+/-3.8 years; range, 1.2-16.0 years) who had no previous treatment for H. pylori underwent upper endoscopy. Biopsies were obtained from the gastric body and antrum for histopathology and rapid urease test. Serum samples collected from all patients were tested for H. pylori IgG antibodies using ICM (Assure H. pylori Rapid Test, Genelabs Diagnostics, Singapore). Immunoblotting (HelicoBlot 2.1, Genelabs Diagnostics, Singapore) was tested in sera of 75 patients to detect antibodies to specific antigens of H. pylori. Positive H. pylori status was defined as positive for both histology and rapid urease test. Of 82 patients, 25 (30.5%) were H. pylori positive, 56 (68.3%) were H. pylori negative and one was equivocal. ICM assay yielded a positive result in 24 of the 25 H. pylori-positive patients (96.0%) and 3 of the 56 H. pylori-negative patients (5.4%). The immunoblotting yielded a positive result in all of 22 H. pylori-positive patients (100%) and in 2 of the 52 H. pylori-negative patients (3.8%). Obtained ICM's sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 96.0, 94.6, 88.9, 98.1 and 95.1%, with immunoblotting 100.0, 96.2, 91.6, 100.0, and 97.3%, respectively. The immunochromatographic and immunoblot tests are non-invasive, reliable and useful for the diagnosis of H. pylori infection in Thai children.

Diagnostic accuracy of the C-urea breath test in children: adjustment of the cut-off value according to age

BACKGROUND AND AIMS

The (13)C-urea breath test ((13)C-UBT) is a reliable non-invasive method of diagnosing Helicobacter pylori infection in adults and children. However, only a few validation studies have been performed on the (13)C-UBT in very young children. The purpose of the present study was to evaluate the diagnostic accuracy of the (13)C-UBT according to age, and to determine the optimal cut-off value in children.

METHODS

A total of 307 (13)C-UBT were performed in 274 children. All were compared with the results of endoscopic biopsy-based methods to confirm H. pylori infection. Seventy-five milligrams of (13)C-urea was ingested without a test meal. Two breath samples were collected at 0 and 30 min. The optimal cut-off value of the (13)C-UBT was assessed by determining the sensitivity, specificity, false negative, and false positive results, at cut-off values ranging from 2.0 to 10.0 per thousand.

RESULTS

The delta over baseline (DOB) values of the (13)C-UBT showed a significant negative correlation with age in both the H. pylori-positive group (r = -0.309; P = 0.005) and the H. pylori-negative group (r = -0.162; P = 0.015). High false positive results and low specificity were noted in children aged 6 years or less compared with children older than 6 years at a cut-off value of 4.0 per thousand (false positives; 8.3%vs 0.85%, specificity; 89.8%vs 98.8%). After adjusting the cut-off value, the optimal cut-off values were found to be 4.0 per thousand in children older than 6 years and 7.0 per thousand in children aged 6 years or less.

CONCLUSIONS

The cut-off value of the (13)C-UBT recommended regardless of age must be adjusted in preschool children to reduce the false positive results.

Helicobacter pylori-specific immune responses of children: implications for future vaccination strategy

We analyzed the specific anti-Helicobacter pylori immunoglobulin G (IgG) antibody profile for a sample of 824 asymptomatic schoolchildren in southern Germany (mean age, 10.7 +/- 0.65 years) with an H. pylori-specific IgG enzyme-linked immunosorbent assay and Western blot analysis. The prevalence of infection was 19.8% (95% confidence interval, 17.1 to 22.7%). The immunoresponses were characterized predominantly by antibodies against low-molecular-mass antigens of 14 and 29 kDa, with a significant difference between children of German and Turkish nationalities (P = 0.0012 and P < 0.0001, respectively).

Serum ferritin and Helicobacter pylori infection in children: a sero-epidemiologic study in Korea

BACKGROUND

Helicobacter pylori infection is known to affect iron metabolism and serum ferritin levels, which are reduced in adults with H. pylori infection. The aim of the present study was to investigate the association between H. pylori infection and iron status in healthy Korean children.

METHODS

The H. pylori seropositivity in 753 schoolchildren aged 6-12 years was screened for using an ELISA and confirmed by western blot analyses. Serum ferritin levels were measured using an immunoradiometric assay in 36 H. pylori-seropositive children and in 72 age- and gender-matched seronegative controls.

RESULTS

The median serum ferritin levels were significantly lower in H. pylori-seropositive children than in seronegative controls (24 vs 39 ng/mL; P < 0.001). The prevalence of iron deficiency (ferritin < 15 ng/mL) in H. pylori-seropositive children was significantly higher (13.9%) than in seronegative children (2.8%). This association persisted after adjusting for age and their socioeconomic status (odds ratio, 5.6; 95% confidence interval, 1.0-30.6).

CONCLUSION

Serum ferritin levels are reduced in children with H. pylori infection. The H. pylori infection may lead to iron deficiency in children.

Higher seroprevalence of Helicobacter pylori infection in Korean adolescent athletes compared to age- and sex-matched non-athletes

BACKGROUND

Poor living conditions, such as overcrowding and bed-sharing, are reported to be significant risk factors for Helicobacter pylori infection throughout childhood. We investigated the prevalence of H. pylori infection in Korean athletes who are obliged to live together in training camps for more than 6 months in a year.

METHODS

Blood sampling and surveying through questionnaire were performed on 440 students from a regular high school (228 boys and 212 girls) and 220 athletes (148 boys and 72 girls) of a physical education high school. We measured serum immunoglobulin G antibody (IgG Ab) to H. pylori in order to compare the prevalence of H. pylori infection between normal adolescents and athletes. In addition, we conducted a nutritional analysis and questionnaire survey for socioeconomic status in order to compare other risk factors that might influence H. pylori infection between groups.

RESULTS

The prevalence of H. pylori infection in athletes (43.2%) was higher than that in the controls (22.7%). No significant differences in the nutritional factors or socioeconomic status, such as Hollingshead index, type of house, number of siblings, and crowding index, were found between the groups. Multivariate analysis showed that crowding and the difference in school type were the significant predictors of H. pylori seropositivity after controlling for dietary and socioeconomic factors.

CONCLUSION

The seroprevalence of H. pylori infection was higher in adolescent athletes than in age- and sex-matched regular students. Further prospective study is needed to confirm the observation.

Evaluation of two commercial enzyme immunoassays, testing immunoglobulin G (IgG) and IgA responses, for diagnosis of Helicobacter pylori infection in children

Serological testing to diagnose Helicobacter pylori infection in children is still controversial, although commonly used in clinical practice. We compared the immunoglobulin G (IgG) and IgA results of two commercially available enzyme immunoassays (EIAs) (Pyloriset IgG and IgA and Enzygnost II IgG and IgA) for 175 children with abdominal symptoms divided into three age groups (0 to < or =6 years, n = 47; >6 to < or =12 years, n = 77; >12 years, n = 51). A child was considered H. pylori infected if at least two of three tests (histology, rapid urease test, 13C-urea breath test) or culture were positive and noninfected if all results were concordantly negative. Of 175 children, 93 (53%) were H. pylori negative and 82 were H. pylori positive. With the recommended cutoff values, the overall specificity was excellent for all four EIAs (95.7 to 97.8%) regardless of age. Sensitivity varied markedly between tests and was 92.7, 70.7, 47.5, and 24.4% for Enzygnost II IgG, Pyloriset IgG, Enzygnost II IgA, and Pyloriset IgA, respectively. Sensitivity was low in the youngest age group (25 to 33.3%), except for Enzygnost II IgG (91.6%). Receiver-operating curve analyses revealed that lower cutoff values would improve the accuracy of all of the tests except Enzygnost II IgG. Measurement of specific IgA, in addition to IgG, antibodies hardly improved the sensitivity. The specificity of commercial serological tests is high in children when the cutoff values obtained from adults are used. In contrast, sensitivity is variable, with a strong age dependence in some, but not all, tests. We speculate that young children may have a different immune response to H. pylori, with preferable responses to certain antigens, as well as lower titers than adults. The Pyloriset test may fail to recognize these specific antibodies.

Helicobacter pylori-associated iron-deficiency anemia in adolescent female athletes

OBJECTIVE

The objective was to investigate the role of Helicobacter pylori infection in iron-deficiency anemia (IDA) of pubescent athletes.

STUDY DESIGN

Blood sampling and a questionnaire survey were performed on 440 regular high school students and 220 athletes of a physical education high school. Hemoglobin, serum iron, total iron-binding capacity, ferritin, and immunoglobulin G antibody to H. pylori were measured to compare the prevalence of IDA and H. pylori infection in the groups. Nutritional analysis and a questionnaire survey for socioeconomic status were undertaken to compare and control for other risk factors that might influence IDA and H. pylori infection in the groups. In those with IDA coexistent with H. pylori infection, we also determined whether IDA can be managed by H pylori eradication.

RESULTS

The prevalence rates of IDA, H pylori infection, and H. pylori -associated IDA in female athletes were higher than in the control group. The relative risk of IDA was 2.9 (95% CI, 1.5 to 5.6) for those with H. pylori infection. Athletes who exhibited H. pylori -associated IDA showed significant increases in hemoglobin, iron, and ferritin levels after H. pylori eradication. The subjects in the control group who were treated orally with iron alone showed no significant changes.

CONCLUSION

Adolescent female athletes may have development of H. pylori -associated IDA, which can be managed by H. pylori eradication.

The cost-effectiveness of diagnostic testing strategies for Helicobacter pylori

OBJECTIVE

Several noninvasive methods are now available for diagnosing Helicobacter pylori infection. Because the prevalence of H. pylori infection is variable in patients requiring testing, the optimal testing strategies may vary under different conditions. The aim of this study was to evaluate the cost-effectiveness of competing diagnostic strategies for H. pylori in patients with varying H. pylori prevalence.

METHODS

A decision analysis was performed comparing the costs per number of correct diagnoses achieved by alternative sequential testing strategies. Estimates of H. pylori prevalence and test characteristics were derived from a systematic review of the MEDLINE bibliographic database. Cost estimates were derived from the 2000 Medicare Fee Schedule.

RESULTS

The enzyme-linked immunosorbent assay (ELISA) test had the lowest cost per correct diagnosis at low (30%), intermediate (60%), and high (90%) prevalence ($90-$95/correct diagnosis), but its diagnostic accuracy was low (80-84%). At low and intermediate prevalence the stool test was more accurate (93%), with an average cost of $126-$127 per correct diagnosis. Additional confirmatory testing of positive or negative tests increased the diagnostic accuracy of the stool test, but had high incremental costs. ELISA testing was preferable when prevalence rates were very high (90%), and using a confirmatory urea breath test for negative ELISA tests increased the diagnostic accuracy to 96%, with modest incremental costs. If the cost of the breath test was <$50 or if the cost of the stool test is >$82, breath testing became preferable to stool testing. If the cost of the stool test fell to <$20, it became preferable to ELISA. Similarly, if the cost of the ELISA serology was >$39 then stool testing became preferable at all prevalence rates. Fingerstick whole blood tests were not cost-effective.

CONCLUSIONS

The choice of an initial test for H. pylori detection depends on the prevalence of H. pylori infection and the value placed on increased diagnostic accuracy. Although ELISA results in the lowest cost-effectiveness ratios, in patients at low-intermediate pretest probability of infection, the stool test provides increased accuracy, with modest incremental costs.

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 infection with iron deficiency anaemia and subnormal growth at puberty

The purpose of this study was to determine whether Helicobacter pylori infection can contribute to growth deficit, especially in pubescent children who need large amounts of iron for growth. A structured questionnaire was sent to the parents of 532 healthy children aged 10 to 15 years (mean 12.9) to obtain demographic information on the parents and the environment. Of the 532 questionnaires sent out, 375 (70.5%; 170 girls and 205 boys) were returned. After collecting blood samples from participants, haemoglobin, serum iron, total iron binding capacity, serum ferritin, and serum IgG antibodies to H pylori were measured. The effects of risk factors such as H pylori infection, iron deficiency anaemia, sex, socioeconomic status, type of house, and crowding index on growth were analysed using multiple regression analysis. Of 63 H pylori positive children, 18 (28.6%) were below the 25th centile values for height, compared with 63 of 312 (20.2%) H pylori negative children. The prevalence rate of H pylori infection was 15.5% (53 of 343) in children without iron deficiency anaemia and 31.3% (10 of 32) in those affected. The relative risk of short stature was 2.2 (95% confidence interval (CI), 1.0 to 4.8) for iron deficiency anaemia, and 1.4 (95% CI, 0.8 to 2.4) for H pylori infection. The mean height was significantly lower in the group having both H pylori infection and iron deficiency anaemia. Therefore, H pylori infection accompanied by iron deficiency anaemia, rather than H pylori infection per se, might delay pubertal growth.

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.

Cost-effectiveness of noninvasive testing and treatment strategies for H. pylori infection in children with dyspepsia

OBJECTIVE

We sought to model the cost-effectiveness of endoscopy, noninvasive testing and treatment strategies for Helicobacter pylori infection in children with recurrent abdominal pain in two health care systems, those of the United States and Finland.

METHODS

Initial serological testing and treatment was compared to empirical treatment with antimicrobials, endoscopy with rapid urease testing, and 13C urea breath testing. Key assumptions and ranges were obtained from the published literature. Costs were determined for the acquisition of various tests and actual reimbursement figures were used for procedural costs.

RESULTS

The disease management costs were very similar for both endoscopy ($643.00) and serology ($646.00) in the United States. In Finland, endoscopy ($173.00) was less expensive than serology ($192.00). The 13C urea breath test was the most expensive procedure in the United States. Sensitivity analysis demonstrated that serological testing became the preferred path if its cost was < $42 in the United States. Empirical treatment of children with dyspepsia was not cost-effective in either country. Sensitivity analysis showed that when prevalence of infection was > 53% in children with recurrent abdominal pain, empirical therapy with endoscopy reserved for failures was the optimal path.

CONCLUSIONS

In developed countries like the United States and Finland, significant cost savings are unlikely with an initial test and treat strategy based on serology. Noninvasive testing and treatment of H. pylori infection can be cost-effective in populations with highly prevalent rates of infection.