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.     

Western blotting is useful in the salivary diagnosis of Helicobacter pylori infection

BACKGROUND: The salivary diagnosis of Helicobacter pylori infection offers attractive possibilities for the epidemiological study of infection in children. Salivary enzyme linked immunosorbent assay (ELISA) is less reliable then serum ELISA, owing to variable transudation of immunoglobulin. In addition, children are more difficult to study because of lower specific serum antibody concentrations to H pylori. The performance of salivary western blotting in comparison with serum western blotting and serum ELISA was investigated in school children. SUBJECTS AND METHODS: Paired serum and saliva specimens were obtained from 669 [corrected] school children aged 9-11 in 10 British towns. All saliva and serum specimens were first analysed by ELISA; subsequently, western blotting of both specimens was performed on 31 and 34 specimens, respectively, to establish the criteria for positivity for western blotting. The remaining 121 specimens were then tested blindly and saliva was compared with the serum. RESULTS: The sensitivity and specificity of salivary ELISA in the 669 [corrected] specimens was 32 of 50 (64%) and 530 of 619 (86%) [corrected], respectively, when compared with serum ELISA. The western blotting validation was performed on 28 subjects with positive serum and positive salivary ELISA, 28 saliva positives with negative serum, 16 saliva negatives with positive serum, and 50 doubly negative subjects. Compared with serum western blots, the sensitivity and specificity of salivary western blots was 38 of 47 (81%) and 68 of 75 (91%), respectively. Using serum ELISA as the gold standard, the sensitivity and specificity were 32 of 44 (73%) and 72 of 78 (92%), respectively, the specificity being significantly higher than salivary ELISA (p < 0.001). CONCLUSION: Salivary western blotting for IgG is useful in the diagnosis of H pylori infection and is superior to ELISA. It also permits the identification of pathogenic strains.     

Prevalence of antibodies against heat-stable antigens from Helicobacter pylori in patients with dyspeptic symptoms and normal persons.

Heat-stable antigens from Helicobacter pylori were investigated for the detection of serum IgG, IgA and IgM antibodies against H. pylori by an ELISA technique. Antibody titers against H. pylori were measured in 167 dyspeptic patients, of whom 96 were H. pylori positive confirmed by culture or microscopy, and in 482 controls (0-98 years). Increased IgG antibody titers were found significantly more often in dyspeptic patients with active chronic gastritis than in patients with normal morphology, as well as in H. pylori-positive patients as compared to H. pylori-negative patients, independent of the endoscopic findings. The heat-stable antigens were compared with acid glycine-extracted antigens and a high degree of concordance was found in the results obtained with the two antigen preparations. The differences in the IgA antibody titers against H. pylori between H. pylori-positive and H. pylori-negative dyspeptic patients were significant and may be useful to confirm a borderline IgG result. No differences were found in IgM antibody titer between H. pylori-positive and -negative patients. The greatest age-dependent increase in IgG and IgA antibody titers was found in children, and if a lower cut-off level is used for children than for adults, as has been proposed, the proportion of people with increased antibody titers against H. pylori would be almost constant from the age of between five and 10 years until the time between 61 and 80 years. Comparison of H. pylori IgG antibodies with IgG antibodies against Campylobacter jejuni and total antibodies against cytomegalovirus (CMV) showed a greater similarity between H. pylori and C. jejuni (R = 0.51) than between H. pylori and CMV (R = 0.22). This may possibly be caused by cross-reactions between H. pylori and C. jejuni. The H. pylori heat-stabile antigen seems not to be very different from other crude H. pylori antigens like acid glycine-extracted antigens, but purification and characterization of the antigens are needed to improve antibody assays.     

Serodiagnosis of Helicobacter pylori infection in childhood.

Sera from 100 children (ages, 6 to 16 years) presenting with upper gastrointestinal symptoms were examined for antibodies to Helicobacter pylori by enzyme-linked immunosorbent assay (ELISA) based on crude, loosely cell-associated antigens and a partially purified urease antigen preparation. All children underwent endoscopy, and 20 children were shown to have H. pylori infection by histology or direct culture. Serum anti-H. pylori immunoglobulin G (IgG) levels (crude antigen) were clearly raised in the infected group, particularly after preabsorption of sera against a Campylobacter jejuni antigen preparation, while IgM and IgA ELISA determinations did not discriminate between infected and H. pylori-negative patients. Only 14 children in the infected group had raised anti-urease IgG levels. Two patients in whom the organism was not demonstrated or cultured had raised specific IgG levels against both crude and urease antigens and pathological features consistent with H. pylori disease. Immunoblotting studies did not reveal any single protein antigen or simple combination of antigens that could be considered as a candidate for a more defined serodiagnostic reagent. Anti-H. pylori antibody determinations (crude antigen) performed on posttreatment samples from children in whom the organism could no longer be demonstrated suggested that sustained IgG levels may not be a reliable index of treatment failure. An IgG ELISA based on crude, loosely cell-associated antigens of H. pylori can be used for the serodiagnosis of H. pylori infection in childhood.     

Transient and persistent Helicobacter pylori colonization in Native American children

Helicobacter pylori is chiefly acquired in childhood, but the exact timing of acquisition is not well understood. The main goal of this study was to assess H. pylori acquisition in a pediatric population. We studied two cohorts of Native American children: a birth cohort of 50 children and 58 older children (mean age, 53 months). We measured serum immunoglobulin G (IgG), IgM, and IgA antibodies to H. pylori whole-cell antigen and IgG antibodies to CagA. Among 44 birth cohort children monitored for more than 12 months, 24 (54.5%) had seroconversions, 7 (15.9%) were transient, and 17 (38.6%) were persistent. Among the older children, 49 (84.5%) of the 58 children were monitored for 1 year; 34 (69.4%) had H. pylori antibodies at study entry. During the next year, 7 (20.6%) children seroreverted, and of 15 initially negative children, 5 (33.3%) seroconverted. In both groups, evaluation of CagA antibodies increased the sensitivity of H. pylori detection. Serum pepsinogen I (PGI) levels in H. pylori-negative children rose significantly until age 6 months and remained constant for the next 19 months. At the time of H. pylori seroconversion, PGI peaked to levels significantly higher than in the never-seroconverted (P = 0.02) and the pre-seroconverted (P = 0.03) children, but then declined to levels paralleling those of H. pylori-negative children. Thus, H. pylori acquisition, accompanied by a transient PGI increase, was frequent in this population, especially in the second and third years of life, but often was brief.     

Diagnosis of Helicobacter pylori infection by specific gastric mucosal IgA and IgG pylori antibodies.

AIMS--To investigate the diagnostic value of mucosal IgA and IgG Helicobacter pylori antibodies. METHODS--The study population comprised 209 consecutive patients with severe dyspeptic complaints referred for upper gastrointestinal endoscopy. A positive culture or histological identification of H pylori in gastric biopsy specimens, or both, were used to confirm infection. Specific IgA and IgG H pylori antibodies were determined using a modified ELISA technique. RESULTS--Of the 209 patients, 137 were infected with H pylori. The diagnostic value of systemic IgA and IgG H pylori antibodies was confirmed. Systemic IgA antibodies had a sensitivity of 76.6% (95% confidence interval 69.5-83.7) and a specificity of 94.4% (89.1-99.7). The sensitivity and specificity for systemic IgG antibodies were, respectively, 97.1% (94.3-99.9) and 98.6% (95.9-100). A moderate but clinically important correlation was found between local and systemic IgA and IgG. Mucosal IgA H pylori antibodies had a sensitivity of 98.5% (96.5-100) and a specificity of 91.7% (85.3-98.1), while for IgG these figures were, respectively, 88.3% (82.9-93.7) and 98.6% (95.9-100). As a diagnostic test mucosal IgA H pylori antibodies were comparable with culture and histology. CONCLUSION--Determination of local IgA and IgG H pylori antibody levels is a highly sensitive and specific 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.     

High prevalence of IgG and IgA antibodies to 19-kDa Helicobacter pylori-associated lipoprotein in chronic urticaria

BACKGROUND: Chronic urticaria has been described in patients with Helicobacter pylori infection. We studied the titer of IgG and IgA type antibodies against H. pylori in patients with and without urticaria of unknown etiology. We also investigated the prevalence of antibodies against H. pylori-associated lipoprotein 20 (lpp20) in patients with and without chronic urticaria. METHODS: The concentration of anti-H. pylori antibodies (IgG and IgA) was determined by the RIDA test. The level of anti-lpp20 antibodies was determined by Western blot using various H. pylori antigens (from 19 to 120 kDa). RESULTS: Patients with chronic urticaria and H. pylori infection (subgroup 1, n = 33) had high IgG and IgA titers whereas all patients with chronic urticaria and without H. pylori infection (subgroup 2, n = 23) were seronegative (P = 0.0128 for IgG and P = 0.003 for IgA). Titers in subgroup 1 did not differ significantly from a control group (n = 33) with severe H. pylori-associated gastritis without urticaria. The prevalence of the anti-lpp20 antibodies was significantly higher in subgroup 1 compared to the control group (93.9 vs 21.2%, P < 0.0001 for IgG, and 46.1 vs 6.3%, P < 0.0029 for IgA). CONCLUSIONS: We suggest that IgG and IgA antibodies to H. pylori-associated lpp20 may play role in the pathogenesis of chronic urticaria.     

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.     

Saliva and sera IgA and IgG in Egyptian Giardia-infected children

Giardiasis is a gastrointestinal infection of wide distribution that is more prevalent in childhood. Easy and rapid diagnosis of giardiasis is essential for reduction of this infection. This cross-sectional study included 62 children in which collection of saliva, stool and serum samples was performed. An enzyme-linked immunosorbent assay (ELISA) technique was evaluated to detect IgA and IgG responses in both saliva and serum samples. Twenty-two children were positive for Giardia duodenalis infection by direct examination of faecal specimens, 20 non-infected and 20 infected with other parasites. Salivary and serum IgA and IgG responses against G. duodenalis infection were significantly higher in Giardia parasitized than non-Giardia parasitized children (p?相似文献   

Diagnosis of norwalk virus infection by indirect enzyme immunoassay detection of salivary antibodies to recombinant norwalk virus antigen

Simple diagnostic tests are needed for the detection of norovirus (NoV) outbreaks. Salivary antibody assays provide an attractive alternative to collecting and testing serum or stool samples. Antibodies to Norwalk virus (NV) in oral fluid samples were compared with NV antibodies in serum collected from 38 volunteers challenged with NV inoculum. Pre- and postchallenge (day 4, 8, 14, and 21) saliva and serum samples were examined by enzyme immunoassay (EIA) using recombinant NV antigen. Of 18 infected subjects (those who shed NV in stool or who demonstrated immunoglobulin G [IgG] seroconversion), 15 (83%) had > or =4-fold increases in NV-specific salivary IgA and 15 (83%) had > or =4-fold increases in NV-specific salivary IgG when prechallenge and postchallenge saliva samples were compared. When the results of the IgA and IgG assays were combined, all 18 infected subjects showed > or =4-fold increases in NV-specific salivary IgG or IgA postchallenge titers compared to their prechallenge titers. One of 19 uninfected subjects had a > or =4-fold increase in NV-specific salivary IgG. The sensitivity of the combined assay results was 100%, and the specificity was 95%. NV-specific salivary IgA titers peaked around 14 days postchallenge. NV-specific salivary IgG and serum IgG titers continued to rise through 21 days postchallenge. The application of this EIA to an elementary school outbreak indicated that 67% of the subjects with confirmed infections had >4-fold rises in anti-NoV IgA when an antigen in the same genetic cluster as the outbreak virus was used. This is the first documented mucosal antibody response to NoV in children. This EIA provides a useful approach for diagnosing NoV outbreaks.     

Local immune response in Helicobacter pylori-infected cats and identification of H. pylori in saliva, gastric fluid and faeces.

Helicobacter pylori-infected cats were screened by culture and polymerase chain reaction (PCR) for the presence of H. pylori in salivary secretions, gastric juice, gastric tissue and faeces. H. pylori was cultured from salivary secretions in six of 12 (50%) cats and from gastric fluid samples in 11 of 12 (91%) cats. A 298 base pair polymerase chain reactions (PCR) product specific for an H. pylori 26000 MW surface protein was amplified from dental plaque samples from five of 12 (42%) cats and from the faeces of four of five (80%) cats studied. Analyses of serum and mucosal secretions by enzyme-linked immunosorbent assay (ELISA) revealed an H. pylori-specific immunoglobulin G (IgG) response, and elevated IgA anti-H. pylori antibody levels in salivary and local gastric secretions. Immunohistochemical analyses of gastric tissue revealed the presence of IgM+ B cells assembled into multiple lymphoid follicles surrounded by clusters of CD4+ and CD8+ T cells. The lamina propria also contained single cells or aggregates of IgA+ and IgM+ B cells. These observations show that H. pylori can be identified in feline mucosal secretions, and that a localized IgA immune response develops in gastric tissue of H. pylori-infected cats. The findings suggest a zoonotic risk from exposure to personnel handling H. pylori-infected cats in vivaria.     

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.     

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.     

Detection of anti-VacA antibody responses in serum and gastric juice samples using type s1/m1 and s2/m2 Helicobacter pylori VacA antigens.

Several different families of vacuolating toxin (vacA) alleles are present in Helicobacter pylori, and they encode products with differing functional activities. H. pylori strains containing certain types of vacA alleles have been associated with an increased risk for peptic ulcer disease. In this study, we tested serum samples and gastric juice from 19 H. pylori-negative and 39 H. pylori-positive patients for enzyme-linked immunosorbent assay reactivity with two different types of VacA antigens (types s1/m1 and s2/m2), which were purified from H. pylori 60190 and 86-338, respectively. Both antigens were recognized better by serum immunoglobulin G (IgG) from H. pylori-positive persons than by serum IgG from H. pylori-negative persons (P < 0.01). The s1/m1 VacA antigen was better recognized by sera from patients carrying vacA type s1/m1 strains than by sera from patients carrying vacA type s2/m2 or s1/m2 strains (P < 0.01). Conversely, the s2/m2 VacA antigen was better recognized by sera from patients carrying type s2/m2 or s1/m2 strains (P = 0.03). Serum IgG anti-VacA antibodies were present more frequently in patients carrying type s1/m1 strains than in other H. pylori-positive patients (P = 0.0002). In addition, the highest levels of IgA anti-VacA antibodies were detected in the gastric juice of patients carrying type s1/m1 strains. These data indicate that different VacA isoforms have distinct antigenic properties and that multiple forms of VacA elicit antibody responses in H. pylori-positive humans.     

PELA幽门螺杆菌口服疫苗微球黏膜免疫研究

目的：应用复乳挥发法制备PELA泛影葡胺显影微球与缨门螺杆菌超声上清口服疫苗微球，并进行靶向与黏膜免疫研究。方法：采用CT技术，研究显影微球的靶向，PELA幽门曙杆菌超声上清口服疫苗微球口服免疫小鼠后，运用ELISA法检测血清，唾液，肠粘液的抗体改变情况，ELISPOT法分析派伊尔氏结（PP结）抗原特异性抗体形成细胞（ASC）的数量增减，结果；口粒径在10um以下的微球，首先粘附在胃肠黏膜表面，后投递于PP结；H.pylori疫苗微球免疫后可诱导较高的唾液sIgA水平和肠道sIgA反应，PP结抗原特异性抗体形成细胞（ASC）数量与肠道 sIgA水平密切相关，结论：可生物降解的PELA微球可用于靶向口服疫苗的研究。     

Use of Helicobacter pylori-specific antibodies in the evaluation of intestinal metaplasia and gastric dysplasia

It is believed that Helicobacter pylori acts mainly during the initial phases of gastric carcinogenesis. Therefore, this study aims to assess the usefulness of H. pylori diagnosis in patients with chronic gastritis (CG), intestinal metaplasia (IM) and dysplasia--conditions that are associated with gastric cancer. A cross-sectional study of 94 patients was performed, which involved endoscopic biopsy and determination of specific serum anti-H. pylori antibodies (IgA, IgG and IgM) by enzyme-linked immunosorbent assay (ELISA). Biopsies were taken from the gastric antrum and corpus, and from endoscopic lesions. Two specimens per patient were used for bacterial culture. H. pylori infection status, used as the gold standard, was based on culture results. Validity measures were determined and receiver operating curve (ROC) was used to determine the best cut-off for serum antibody levels. Histopathological evaluation (n = 160) was performed independently by two pathologists. Lesions consistent with CG were found in 86 patients (91%), consistent with IM in 69 patients (73%) and with dysplasia in five patients (5%). In the 86 patients with CG, 38 (44%) were infected by H. pylori, as were 26 (38%) and one (20%) with IM and dysplasia, respectively (P=0.039). Area under the curve (AUC) was 0.40 (95% confidence interval [CI]: 0.28-0.51) for IgM, 0.69 (0.58-0.80) for IgA and 0.83 (0.74-0.92) for IgG for the diagnosis of H. pylori infection. Best cut-off was 41 u/mL for IgG, with a sensitivity (95% CI) of 90% (84-96%) and a negative predictive value (NPV) of 91% (85-97%). For IgA the results were 22 u/mL, 74% (65-83%) and 77% (68-86%), respectively. Prevalence of H. pylori appeared to decrease with increasing severity of the gastric lesion. In conclusion, it is suggested that non-invasive serological evaluation of anti-H. pylori (IgG) status after eradication therapy for peptic ulcer disease could be extended, after proper assessment of cut-off values and their validation, to the follow-up of patients with CG and IM.     

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.     

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.     

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.