Immune responses to Helicobacter pylori in children with recurrent abdominal pain.

The systemic immune response to Helicobacter pylori was examined in 69 children with recurrent abdominal pain and upper gastrointestinal symptoms. Twenty one (30%) children were histologically positive for H pylori. Eighteen of the 21 positive subjects and two H pylori negative subjects (one with normal mucosa, one with lymphocytic gastritis) were positive for H pylori IgG antibodies by enzyme linked immunosorbent assay (ELISA) (86% sensitivity, 98% specificity). In children with H pylori associated gastritis, there was a significant positive correlation (p less than 0.05) between IgG antibody titres and patient age. Intra-assay comparison of sera from histologically negative adults with those of histologically negative children showed that the cut off for positivity in the ELISA for adults was greater than that for children. Immunoblotting showed IgG positivity in 20 of the 21 patients with H pylori infection (95% sensitivity). Both ELISA and immunoblotting for IgA and IgM H pylori antibodies had poor discriminatory value for determining infection. Serological detection of H pylori IgG antibodies seems to be valuable in the assessment of children presenting with recurrent abdominal pain and other gastrointestinal symptoms, but assays must first be validated in paediatric populations.     

Detection of immunoglobulin G antibodies to Helicobacter pylori in urine by an enzyme immunoassay method.

Urine and serum samples from 306 patients undergoing upper endoscopy were evaluated prospectively to determine the presence of immunoglobulin G (IgG) antibodies to Helicobacter pylori by an enzyme immunoassay method. Forty-nine selected urine specimens were also tested by Western blotting (immunoblotting). When compared with bioptic methods (culture, stain, urease testing), the sensitivity and specificity of the assay for urine IgG to H. pylori were 95.9 and 90%, respectively. Results of testing of serum and urine for IgG to H. pylori were concordant for 95% of samples. Western blot analysis revealed a highly variable antibody response to H. pylori antigens among patients. Detection of IgG antibody to H. pylori in urine is simple and reflects the presence or absence of H. pylori infection.     

Use of serum-specific immunoglobulins A and G for detection of Helicobacter pylori infection in patients with chronic gastritis by immunoblot analysis.

Multiple invasive and noninvasive tests for detecting Helicobacter pylori infection are available. The current "gold standard" for the diagnosis of H. pylori infection requires histology and the rapid urease test. Our aim was to test the performance of immunoglobulin A (IgA) and IgG immunoblot assays in comparison with that of the gold standard tests for the diagnosis of H. pylori infection. Ninety patients who underwent gastroscopy were analyzed in a prospective study. Fifty-nine of them were defined to be H. pylori positive by the gold standard tests. The IgA and IgG immunoblot assays correctly identified H. pylori infection in 17 and 58 of these patients, respectively, indicating that determination of IgA antibodies seems to be of low diagnostic value for H. pylori infection. In contrast, the sensitivity and specificity of the IgG immunoblot assay were 98 and 71%, respectively, with positive and negative predictive values of 87 and 96%, respectively. Therefore, the IgG immunoblot assay proved to be a sensitive and useful, noninvasive test for the diagnosis of H. pylori infection.     

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.     

Diagnosis of Helicobacter pylori infection by using pyloriset EIA-G and EIA-A for detection of serum immunoglobulin G (IgG) and IgA antibodies.

We evaluated the performance of new enzyme immunoassay (EIA) kits (Pyloriset; Orion Corporation, Orion Diagnostica, Espoo, Finland) for the detection of immunoglobulin G (IgG) and IgA antibodies to Helicobacter pylori in serum. Serum samples from 195 patients with upper abdominal complaints were collected. Biopsy specimens of the gastric mucosae were taken for histological analysis and bacterial culture. The sensitivity, specificity, and positive and negative predictive values, and efficacy of the Pyloriset EIA-G in detecting IgG antibodies to H. pylori were 92, 84, 88, 90, and 89%, respectively, when compared with those of the reference methods used. The corresponding data for detection of IgA antibodies were 80, 89, 89, 79, and 84%, respectively. The overall prevalence of defined H. pylori positivity was 54%. Moreover, the antibody tests showed a very good correlation with the biopsy findings. IgG antibodies were found in 93% of sera from patients with documented gastritis and H. pylori positivity, whereas only 4% of the sera from patients with documented gastritis and H. pylori-negative patients was positive. The results obtained for IgA antibodies were 81 and 6%, respectively. We conclude that the Pyloriset EIA-G, the test for IgG antibodies, is a good and reliable test for the detection of antibodies to H. pylori and as an indication of H. pylori infection. The determination of IgA antibodies may be used as a test that complements the IgG antibody assay.     

Diagnostic value of detection of IgM antibodies to Helicobacter pylori.

This report describes the diagnostic value of anti-Helicobacter pylori IgM detection. Serum samples from 9043 symptomatic and asymptomatic individuals were evaluated with ELISA for the presence of anti-H. pylori IgG, IgM, and IgA. The specificity of detected IgM was confirmed by inhibition and cross-reactivity assays. Treatment of IgM-positive specimens with 1% 2-mercaptoethanol resulted in approximately 90% inhibition. Our data suggest a low level of cross-reactivity (5%) between H. pylori and four different enteropathogenic bacteria tested. The specificity of anti-H. pylori IgM was also demonstrated by Western blot and linearity studies. Data show that the detected IgM is highly specific. Western blot analysis revealed a variable IgM response to H. pylori antigens among patients, with the most reactive antigenic fractions being in the range of 55- to 100-kDa. Overall, the data confirm the diagnostic value of anti-H. pylori IgM detection. The prevalence of IgM antibodies to H. pylori in tested sera was significantly higher in symptomatic patients (10.4%) than in asymptomatic individuals (1.1%). Likewise, the percentage of sera positive for IgM alone was higher in symptomatic than in asymptomatic groups (3.8 vs 0.22%). About 5% of sera were positive only for IgA. We concluded that ELISA can be used for the detection of specific IgM to H. pylori and that the presence or absence of IgM antibodies to H. pylori may reflect whether or not an acute infection exists.     

Evaluation of a commercial ELISA for serodiagnosis of Helicobacter pylori infection.

A commercial ELISA for the detection of Helicobacter pylori IgG antibodies was evaluated using serum from 242 patients attending an endoscopy clinic. The efficacy of the ELISA was assessed in relation to the histological detection of H pylori on antral mucosal biopsy specimens. In patients under 61 years of age (n = 138) the ELISA was 97.5% sensitive and 85.5% specific for H pylori infection, with a positive predictive value of 91% and a negative predictive value of 96%. Over the whole group the sensitivity of the ELISA was 93.8% and the specificity 79.3%. The positive predictive value and negative predictive values were, respectively, 90% and 87%. These results suggest that the Bio-Rad GAP IgG H pylori ELISA is suitable for serodiagnosis of H pylori infections for most clinical purposes and thus makes H pylori serology available to routine diagnostic laboratories.     

Salivary immunoglobulin G assay to diagnose Helicobacter pylori infection in children.

An in-house enzyme-linked immunosorbent assay (ELISA) for measurement of Helicobacter pylori-specific immunoglobulin G (IgG) and IgA in saliva was evaluated by comparison with histopathologic (Giemsa staining) and biochemical (urease quick test) examination of gastric biopsy specimens obtained from 112 children referred for diagnostic gastroscopy. Serum H. pylori IgG was also measured in a subgroup of 50 children by the same ELISA. Salivary H. pylori IgG levels were significantly higher in H. pylori-positive (n = 57) than in H. pylori-negative (n = 55) children (P < 0.001). The sensitivity and specificity of the salivary IgG test were 93 and 82%, respectively; the positive and negative predictive values were 84 and 92%, respectively; and the accuracy was 87.5%. Salivary H. pylori IgA did not distinguish H. pylori-positive from H. pylori-negative children. The performance of serum H. pylori IgG was slightly (3 to 6%) better than that of salivary H. pylori IgG. The salivary IgG test can be considered a useful tool for the screening of H. pylori infection in children.     

Comparison of three commercially available enzyme-linked immunosorbent assays and biopsy-dependent diagnosis for detecting Helicobacter pylori infection.

We evaluated the performance of three enzyme-linked immunosorbent assays (ELISAs) in detecting serum immunoglobulin G (IgG) and IgA antibodies to Helicobacter pylori; two were new ones from Pyloriset (Pyloriset EIA-G update and Pyloriset EIA-A update; Orion Diagnostica, Espoo, Finland), and the third was the Malakit EIA-G (Biolab, Limal, Belgium). Serum samples from 154 dyspeptic patients were collected. As a reference method, multiple biopsy specimens from different anatomical areas of the stomach were obtained by endoscopy and were analyzed by culture and/or histology and direct urease testing. Accordingly, 126 patients (82%) were found to be H. pylori positive and 28 patients (18%) were found to be H. pylori negative. To validate serology as a predictor of H. pylori infection, sensitivity, specificity, positive and negative predictive values, and accuracy of the assays were calculated against the H. pylori status as determined by the reference method. The corresponding data for the different ELISAs were 100%, 79%, 95%, 100%, and 96% for the Pyloriset ELA-G update, 81%, 89%, 97%, 52%, and 82% for the Pyloriset EIA-A update, and 87%, 86%, 96%, 60%, and 87% for the Malakit EIA-G, respectively. We conclude that the Pyloriset EIA-G update is a reliable and accurate test and that because of its 100% sensitivity, conjunctional IgA testing is not necessary. Its 100% negative predictive value makes it a very useful screening test. For purposes of excluding infection with H. pylori, the performance of the Malakit EIA-G is moderate but can be improved by conjunctional IgA testing. The Pyloriset EIA-A update can be useful as such a conjunctional test.     

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.     

Oral fluid antibody detection in the diagnosis of Helicobacter pylori infection.

The aim of this study was to evaluate an enzyme-linked immunosorbent assay (ELISA) for the detection of anti-Helicobacter pylori specific IgG antibodies in specimens of oral fluid. Antral biopsy specimens, serum and oral fluid samples were collected from 81 patients attending for upper gastrointestinal endoscopy. The presence or absence of current H. pylori infection was determined by culture, histology and urease detection. Anti-H. Pylori specific IgG was detected in serum by an established in-house ELISA and in oral fluid by an ELISA developed for this study. In all, 34 (42%) of 81 patients were positive for H. pylori by one or more of the 'gold standard' tests (culture, histology and urease detection). The oral fluid ELISA had a sensitivity of 94% and specificity of 85% with regard to current H. pylori infection. The serum ELISA had a sensitivity and specificity of 91%. There was an overall agreement of 88% between serum and oral fluid antibody detection. The detection of anti-H. pylori specific IgG in oral fluid by ELISA is comparable in sensitivity and specificity with serum-based methods. Oral fluid-based ELISA could provide a reliable, non-invasive method for the diagnosis of H. pylori infection, and may be of particular benefit for population surveys.     

Correlation of serum antibody titres with invasive methods for rapid detection of Helicobacter pylori infections in symptomatic children

Helicobacter pylori (H. pylori) is causally associated with peptic ulcer disease and gastric carcinoma. Typically, children get infected during the first decade of life, but diseases associated with H. pylori are seen mainly in adults. Multiple diagnostic methods are available for the detection of H. pylori infection. The aim of this study was to evaluate the correlation and diagnostic accuracy of three invasive methods [rapid urease test (RUT), histology and bacterial culture] and one non-invasive method (IgG serology) for diagnosis of H. pylori infection in a prospective cohort study conducted on 50 symptomatic children between two and eighteen years of age. Endoscopies with gastric biopsies were performed for RUT, culture and histopathological examination, respectively. IgG antibodies were measured in patient sera using a commercially available enzyme-linked immunosorbent assay (ELISA). RUT and positive H. pylori IgG antibodies were concordant in 88% (44/50) of patients. Both tests were negative in 32% (16/50), and both were positive in 56% (28/50). Disagreement occurred in 12% (6/50) of the patients: three of them (6%) had positive RUT and negative H. pylori IgG, and another three (6%) had negative RUT and positive H. pylori IgG. A combination of RUT with non-invasive serology constituted the optimum approach to the diagnosis of H. pylori infection in symptomatic children. The non-invasive serological test (ELISA) could not be used alone as the gold standard because it cannot distinguish between active and recently treated infection; and bacterial culture could not be used alone because of its low sensitivity.     

Serologic Diagnosis of Helicobacter pylori Infection in Outpatients Aged 45 Years or Less

The diagnostic accuracy of serological tests for Helicobacter pylori was studied in 145 consecutive outpatients aged 45 years or less referred for gastroscopy. Helicobacter pylori infection can be detected by serological tests, including rapid whole-blood tests. The low prevalence of the disease in young people may have a negative effect on the positive predictive value of a test. In this study, the presence of Helicobacter pylori was assessed by a biopsy urease test and histological examination, and by several serological tests: a rapid whole-blood test on fingerstick blood, a latex agglutination serum test, a commercial enzyme immunoassay (EIA) test, and an in-house EIA for detection of antibodies of both the IgG and IgA classes. Helicobacter pylori infection was diagnosed with invasive tests in 21 (14.5%) patients. The sensitivity, specificity, and positive and negative predictive values of the EIA-based tests, compared to histological examination, were 100%, 96-97%, 81-84%, and 100%, respectively. The positive predictive value of the latex agglutination test was 78%, whereas it was only 47% for the whole-blood rapid test used. Although the results of the whole-blood rapid test were unsatisfactory, the quantitative EIA-based tests could reliably detect Helicobacter pylori among young patients, in whom the prevalence of the infection is low.     

Presence of Helicobacter pylori Antibodies in Haemodialysis Patients

Aim:  Renal dysfunction may influence the colonization of gastric mucosa by urea-splitting bacteria such as Helicobacter pylori , by increasing urea concentrations in the gastric juice. Our aim was to investigate the prevalence of H. pylori in patients with end-stage renal disease (ESRD), receiving long-term haemodialysis treatment.
Methods:  This study included 40 sera from patients with ESRD (29 male and 11 female) undergoing periodic haemodialysis; mean time of treatment was 42.6 months. Using ELISA technique, we investigated the presence of IgG and IgA antibodies against H. pylori as well as IgG CagA (antibodies specific for CagA(+) strains of H. pylori ). Sera from 40 healthy blood donors were used as a control group.
Results:  H. pylori IgG antibodies were detected in 32 out of 40 (80%) patients in the dialysis group, while 31/40 (77.5%) tested positive for IgA. IgG CagA antibodies were present in 13 out of 40 (32.5%). Prevalence of H. pylori IgG, IgA and CagA IgG antibodies in the control group was 33, 7 and 15%, respectively.
Conclusions:  Although international data suggest that prevalence of H. pylori infection is the same in ESRD patients as in healthy individuals, in our study that seems not to be the case. The higher blood and gastric juice urea levels may be a risk factor (among many others), but more studies are required in order to understand the relation of H. pylori infection in this group of patients.     

Comparison of PCR and other diagnostic techniques for detection of Helicobacter pylori infection in dyspeptic patients.

A sensitive and specific PCR-based assay to detect the Helicobacter pylori 16S rRNA gene present in formalin-fixed paraffin-embedded gastric biopsy specimens has been developed. A total of 95 patients with dyspepsia were evaluated for the presence of chronic active gastritis and an infection with H. pylori through the use of diagnostic assays based on biopsy specimens and serology. The "gold standard" for the presence of the bacteria was direct detection in histological sections of biopsy specimens by Giemsa stain. The results obtained with the PCR assay performed on the biopsy specimens (94% sensitivity and 100% specificity) were equivalent to the detection of H. pylori immunoglobulin G antibodies by the commercially available second-generation Cobas Core anti-H. pylori immunoglobulin G enzyme immunoassay (94% sensitivity and 98% specificity) for the diagnosis of H. pylori infection. Urease testing and bacterial culture of the biopsy specimens were inferior (88 and 70% sensitivity and 96% and 98% specificity, respectively). A Western blot (immunoblot) analysis had slightly greater sensitivity (96%), although specificity was reduced to 93%. This research prototype PCR assay was shown to be highly reliable for the detection of infection with H. pylori and the presence of chronic active gastritis in the population studied.     

Serodiagnosis of Helicobacter pylori: comparison of enzyme-linked immunosorbent assays.

Enzyme-linked immunosorbent assays (ELISAs) have been developed to diagnose Helicobacter pylori infection. However, the methods are not standardized. We therefore prospectively evaluated the sensitivities and specificities of ELISAs developed in the United States and the United Kingdom in a study population comprising 41 consecutive symptomatic outpatients and 35 volunteers. At endoscopy, multiple biopsies were obtained for histology and culture and stained sections were graded for chronic gastritis, active chronic gastritis, and density of H. pylori. Serum samples were analyzed for H. pylori by ELISA. The first set of assays for immunoglobulin G (IgG) and IgA used a pool of sonicated isolates of H. pylori from five patients in the United States (antigen A). The second set of assays, developed in the United Kingdom, used three different antigens: antigen 1, an acid-extractable surface antigen; antigen 2, an acid-extractable antigen from an aflagellate variant; and antigen 3, a urease-containing fraction. Cutoff scores for positive results were determined a priori on the basis of previous serological studies. There was close agreement between histology and culture. In the study population, 36% of the individuals were H. pylori positive. The diagnostic value of the different ELISAs were highly comparable, and the crude antigens performed as well as the more purified antigens. The antigen A IgG had a sensitivity and specificity of 96 and 94%, respectively; the values for antigen 1 were 93 and 96%, respectively. The antigen A IgA and antigen 3 assays were the least sensitive tests.(ABSTRACT TRUNCATED AT 250 WORDS)     

A practical single sample dry latex agglutination test for Helicobacter pylori antibody detection.

Assessment of a single serum sample for Helicobacter pylori antibodies is frequently requested in routine diagnostic laboratories. Current enzyme linked immunosorbent assay (ELISA) kits are not ideal for testing small numbers of serum samples and some have low sensitivities, specificities or large grey zones. A panel of 90 serum samples from patients who had presented for routine upper endoscopy was used to compare three kits for the detection of H pylori antibodies: (1) Pyloriset Dry, total antibody latex agglutination, Orion Diagnostica, Espoo, Finland; (2) Pyloriset enzyme immunoassay (EIA), IgG ELISA, Orion; and (3) Hel-p, IgG ELISA, Amrad, Kew, Victoria, Australia. Diagnosis of H pylori positivity was made if culture results and either rapid urease test or histopathology were positive. The sensitivity, specificity, positive, and negative predictive value for each test was as follows: Orion: latex 93.3%, 95.6%, 95.5%, 93.3%, respectively; Orion: EIA-G 84.4%, 97.8%, 97.4%, 84.4%, respectively; and Amrad: EIA-G 100%, 88.9%, 90%, 100%, respectively. The latex test performed better than the EIAs with respect to sensitivity and specificity.     

Correlation between serological and mucosal inflammatory responses to Helicobacter pylori.

In 82 patients who underwent gastroduodenoscopy, acute and chronic gastric mucosal inflammation was scored for severity, and systemic humoral immune responses to Helicobacter pylori antigens were assessed by enzyme-linked immunosorbent assays. On the basis of culture, gastric histology, and serologic evaluation, 33 patients were classified as H. pylori infected and 36 were classified as uninfected. Thirteen patients had negative cultures and stains but were seropositive and were analyzed separately from the other two groups. Specific serum immunoglobulin G (IgG) subclass responses to H. pylori whole-cell antigens and specific IgG responses to the 54-kDa heat shock protein homolog (Hp54K) and vacuolating cytotoxin were significantly greater in infected than in uninfected patients as were specific IgA responses to whole-cell antigens and cytotoxin (P < 0.001). Among the H. pylori-infected persons, serum IgG responses to Hp54K and to the vacuolating cytotoxin were correlated with acute mucosal inflammatory scores. In contrast, serum IgA responses to whole-cell sonicate and to vacuolating cytotoxin were inversely related to chronic inflammatory scores. By multivariant regression analysis, only specific serum IgG responses to Hp54K correlated with severity of inflammation (both acute and chronic; P < 0.001); these responses may be markers of inflammation or these antibodies could play a direct role in the pathogenesis of H. pylori-induced inflammation.     

IgA antibodies in persisting Helicobacter pylori infection in Finnish adults

Most individuals infected with Helicobacter pylori have elevated levels of specific IgG antibodies, but only in about two-thirds of cases does the IgA titre exceed the cut-off level. The aim of this study was to determine whether H. pylori-infected subjects with elevated IgG levels would subsequently produce IgA antibodies, and whether elevated IgA levels increased during infection. Paired sera were available from 336 adults who took part in a large population-based health survey in 1977-1980 and a follow-up study on asthma and atopic diseases in 1997-1998 (series A). Data on paired sera from 224 adults who participated in a population-based health survey in Vammala, Finland in 1973 and who gave a follow-up blood sample in 1994 (series B) were also re-analysed. H. pylori IgG and IgA levels were determined with commercially available (series A) and in-house (series B) enzyme immunoassays. Twenty-one (35%) of the 60 subjects who initially had elevated levels of IgG antibodies only were found to be IgA-positive at follow-up. In those subjects whose baseline and follow-up samples were IgG- and IgA-positive, the median IgA levels increased by 48% and 22% in series A and B (p < 0.0001 and p 0.0241), respectively, whereas the median IgG levels did not change significantly in either series. During H. pylori infection, an increase in specific IgA was reflected by the increase in the number of responders and by the rise in titres.     

Evaluation of a Western blot technique (Helicoblot 2.1) for the diagnosis of Helicobacter pylori infection in children

AIM: We evaluated the performance of Helicoblot 2.1 which differentiates the reactivity to each of the various Helicobacter pylori antigens, and compared the results with those obtained by standard techniques (rapid urease test and histological examination of gastric biopsy) in symptomatic children of different ages living in Antalya, Turkey. METHODS: Eighty-eight children (mean age, 9.15 years) were divided into two groups. The first group included 66 children who were found to be infected with H. pylori. The second group included 22 children who were negative for H. pylori. Serum samples collected from all patients were tested for H. pylori IgG antibodies by immunoblot assay (Helicoblot 2.1). RESULTS: The sensitivity, specificity, positive and negative predictive values for detection of H. pylori infection were 80%, 100%, 100% and 85%, respectively. In children under 7 years of age, the sensitivity of the test was found to be lower than other age groups (P<0.05). No relationship was found between peptic ulcer and cagA antibody positivity (P>0.05). CONCLUSION: Helicoblot 2.1 is a useful non-invasive diagnostic tool for H. pylori infection in children over 6 years of age.