Cross-reactive antigens shared by Pseudomonas aeruginosa, Helicobacter pylori, Campylobacter jejuni, and Haemophilus influenzae may cause false-positive titers of antibody to H. pylori

The role of Helicobacter pylori in cardiovascular toxicity mechanisms

Despite the long history of the concept where infection plays a significant role in cardiovascular diseases (atherosclerosis in particular), today it is relevant and represented a significant interest.

This article discusses H. pylori role in mechanisms of cardiovascular homeostasis disturbance. H. pylori involvement in atherogenic damage of arteries, and/or plaque destabilization is no doubt. This vidence is detailed in this review article.

Helicobacter pylori among patients with symptoms of gastroduodenal ulcer disease in rural Uganda

Introduction

To meet key millennium development goals, the rural population needs to be reached for health assessment and service delivery. Gastroduodenal ulcer disease is a common ailment affecting the health of people in Uganda. A cross-sectional study was conducted at Bwera Hospital in Kasese district of western Uganda, to establish the prevalence and predisposing factors of Helicobacter pylori among gastroduodenal ulcer disease patients.

Methods

A sample of 174 patients with symptoms of gastroduodenal ulcer disease was purposively obtained. Using two laboratory test methods, the prevalence of H. pylori among these patients was determined. A structured questionnaire was administered to participants to establish their demographic background and selected aspects of their lifestyle. Finally, the results obtained by enzyme-linked immunosorbent assay (ELISA) and immunochromatographic rapid test (IRT) were compared.

Results

We established the prevalence of H. pylori as 29.9% (52/174) by ELISA and 37.4% (65/174) by IRT. Cigarette smoking, poor sanitation, and lack of formal education were the significant predisposing factors with p-values <0.05. The two tests gave identical results in 87.9% of the patients.

Discussion

The prevalence of H. pylori by IRT and ELISA test methods was similar to what has been reported elsewhere in developed countries; but was lower than previously reported in developing countries including Uganda. The previous studies in Uganda were carried out in the urban population and on young children; and some used antibody-detection methods only, therefore leading to different prevalence as a result of difference in study population and methods.

Is there a role for symbiotic bacteria in plant virus transmission by insects?

During the process of circulative plant virus transmission by insect vectors, viruses interact with different insect vector tissues prior to transmission to a new host plant. An area of intense debate in the field is whether bacterial symbionts of insect vectors are involved in the virus transmission process. We critically review the literature in this area and present a simple model that can be used to quantitatively settle the debate. The simple model determines whether the symbiont is involved in virus transmission and determines what fraction of the pathogen transmission phenotype is contributed by the symbiont. The model is general and can be applied to any vector-pathogen-symbiont interactions.

Cystic fibrosis, gastroduodenal inflammation, duodenal ulcer, and H. pylori infection: the "cystic fibrosis paradox" revisited

BACKGROUND

In cystic fibrosis (CF) patients a duodenal impaired bicarbonate secretion and unbuffered gastric acid are always described and the development of duodenal ulceration is uncommon (CF paradox). Helicobacter pylori (HP) infection is the main cause for duodenal ulceration and its prevalence in CF patients is controversial.

AIM

The objective of this study is to evaluate HP prevalence, gastric histology, and duodenal ulceration in adult FC patients.

METHODS

32 adult CF patients were submitted to (13)C-urea breath test and serum immunoblotting test for HP diagnosis. Among them, 20 patients were submitted to endoscopy.

RESULTS

19/32 (68%) patients showed positive serology. Endoscopy showed erosive duodenitis (15%), and duodenal ulcer scar in 10%. On duodenal histology, 94.5%, showed active inflammation and 66.7% gastric metaplasia.

CONCLUSION

HP infection prevalence in adult CF patients was similar to that of general Brazilian population. CF patients have all the duodenal spectrum of alterations, including duodenal ulcer. CF paradox may not exist.

Autoimmune thyroid diseases and Helicobacter pylori: The correlation is present only in Graves's disease

AIM: To investigate the correlation between autoimmune thyroid diseases (ATDs) and the prevalence of Cag-A positive strains of Helicobacter pylori (H. pylori) in stool samples.

METHODS: Authors investigated 112 consecutive Caucasian patients (48 females and 4 males with Graves’ disease and 54 females and 6 males with Hashimoto’s thyroiditis HT), at their first diagnosis of ATDs. Authors tested for H. pylori in stool samples using an amplified enzyme immunoassay and Cag-A in serum samples using an enzyme-linked immunoassay method (ELISA). The results were analyzed using the two-sided Fisher’s exact test and the respective odds ratio (OR) was calculated.

RESULTS: A marked correlation was found between the presence of H. pylori (P≤ 0.0001, OR 6.3) and, in particular, Cag-A positive strains (P≤ 0.005, OR 5.3) in Graves’ disease, but not in Hashimoto’s thyroiditis, where authors found only a correlation with Cag-A strains (P≤ 0.005, OR 8.73) but not when H. pylori was present.

CONCLUSION: The marked correlation between H. pylori and Cag-A, found in ATDs, could be dependent on the different expression of adhesion molecules in the gastric mucosa.

Identification of a correlation between Helicobacter pylori infection and Graves' disease

BACKGROUND

Viral and bacterial antigens have been suspected to be able to mimic the antigenic profile of the thyroid cell membrane and to play an important role in the onset of the autoimmune diseases, such as Graves' disease and Hashimoto thyroiditis. The Helicobacter pylori infection is worldwide diffused and is present in the developed countries up to 50% of the population. The presence of the cytotoxin-associated gene A antigens identifies the most virulent strains of the bacterium. Previous studies have demonstrated the possible correlation between the Helicobacter pylori and Hashimoto's thyroiditis but these results are controversial.

AIMS

We studied the prevalence rate of this bacterium in the Graves' disease and two selected subgroups such as the hyperthyroid patients, at the first time of diagnosis, and the euthyroid methimazole-treated patients.

MATERIALS AND METHODS

We analyzed Helicobacter pylori in fresh stool samples with an enzyme immunoassay method and the presence of cytotoxin-associated gene A antigens with a serological test.

RESULTS

Our results show that a significative increased rate of prevalence is present in Graves' patients, when the disease is ongoing, with an overall prevalence of the strains expressing the cytotoxin-associated gene A antigens compared to the control group.

CONCLUSIONS

The association between the Helicobacter pylori and Graves' disease suggests a possible role of this bacterium in the onset and/or the maintenance of the disease.

Selection and characterization of DNA aptamers with binding selectivity to Campylobacter jejuni using whole-cell SELEX

The need for pre-analytical sample processing prior to the application of rapid molecular-based detection of pathogens in food and environmental samples is well established. Although immunocapture has been applied in this regard, alternative ligands such as nucleic acid aptamers have advantages over antibodies such as low cost, ease of production and modification, and comparable stability. To identify DNA aptamers demonstrating binding specificity to Campylobacter jejuni cells, a whole-cell Systemic Evolution of Ligands by EXponential enrichment (SELEX) method was applied to a combinatorial library of FAM-labeled single-stranded DNA molecules. FAM-labeled aptamer sequences with high binding affinity to C. jejuni A9a as determined by flow cytometric analysis were identified. Aptamer ONS-23, which showed particularly high binding affinity in preliminary studies, was chosen for further characterization. This aptamer displayed a dissociation constant (K(d) value) of 292.8 +/- 53.1 nM with 47.27 +/- 5.58% cells fluorescent (bound) in a 1.48-microM aptamer solution. Binding assays to assess the specificity of aptamer ONS-23 showed high binding affinity (25-36%) for all other C. jejuni strains screened (inclusivity) and low apparent binding affinity (1-5%) with non-C. jejuni strains (exclusivity). Whole-cell SELEX is a promising technique to design aptamer-based molecular probes for microbial pathogens without tedious isolation and purification of complex markers or targets.

Helicobacter species in the human colon

OBJECTIVE

To determine the prevalence, frequency and colonization patterns of Helicobacter species throughout the colon.

METHOD

Patients having initial colonoscopy for nonspecific gastrointestinal disturbance had colonic biopsies taken from up to four sites during colonoscopy and examined for evidence of the Helicobacteraceae family using a group-specific PCR. Serum was also collected and examined for IgG reactivity to Helicobacter pylori.

RESULTS

100 patients had colonoscopy of whom 35 were found to have DNA evidence of Helicobacter species throughout the colon, with 22 having H. pylori. Fifteen patients had a demonstrable serum IgG response to H. pylori that was not always associated with molecular evidence of H. pylori DNA in colon biopsies and vice versa. No specific association with colon disease was found in patients with H. pylori infection.

CONCLUSION

We found evidence of Helicobacter infection in a significant number of patients presenting for colonoscopy but no specific association between the presence of these bacteria and colon disease. Our finding of disparity between molecular and serological techniques to detect Helicobacter species suggests that future studies should not rely on serology alone to detect these bacteria in the human colon.

Helicobacter pylori infection and gastric cancer risk: evaluation of 15 H. pylori proteins determined by novel multiplex serology

Infection with Helicobacter pylori is a major cause of gastric cancer (GC). The association likely has been underestimated in the past due to disease-related clearance of the infection. On the other hand, only a minority of the infected individuals develop GC, and better risk stratification is therefore highly desirable. We aimed to assess the association of GC with antibodies to 15 individual H. pylori proteins, determined by novel multiplex serology, to identify potentially relevant risk markers. This analysis was based on 123 GC cases aged 50 to 74 years and 492 age-matched and sex-matched controls from Saarland, Germany. Eight of the antibodies were significantly associated with noncardia GC and seven of them were significantly related to GC at any site. More pronounced associations were observed for noncardia GC; adjusted odds ratios (95% confidence intervals) ranged from 1.60 (1.01-2.54) for HyuA to 5.63 (3.20-9.91) for cytotoxin-associated antigen A (CagA). A dose-response relationship was found between the number of seropositivities and GC (P < 0.001). The seropositivities of CagA and GroEL were found to be independent predictors of GC, which were strongly related to GC risk in a dose-response manner (P < 0.001). In conclusion, GroEL was identified as a new independent risk marker that may contribute to enhanced quantification of H. pylori-related GC risk.

Usefulness of serum IgG4 in the diagnosis and follow up of autoimmune pancreatitis: A systematic literature review and meta-analysis

High circulating serum immunoglobulin G4 (IgG4) levels have been proposed as a marker of autoimmune pancreatitis (AIP). The aim of the present study was to review the data existing in the English literature on the usefulness of the IgG4 serum levels in the diagnosis and follow up of patients with AIP. A total of 159 patients with AIP and 1099 controls were described in seven selected papers reporting the usefulness of serum IgG4 in diagnosing AIP. In total, 304 controls had pancreatic cancer, 96 had autoimmune diseases, and the remaining 699 had other conditions. The summary receiver-operating characteristic curve analysis was carried out by means of Meta-DiSc open-access software. Serum IgG4 showed good accuracy in distinguishing between AIP and the overall controls, pancreatic cancer and other autoimmune diseases (area under the curve [+/- SE]: 0.920 +/- 0.073, 0.914 +/- 0.191, and 0.949 +/- 0.024, respectively). The studies analyzed showed significantly heterogeneous specificity values in each of the three analyses performed. The analysis of the four studies comparing AIP and pancreatic cancers also showed significantly heterogeneous values of sensitivities and odds ratios. Regarding the usefulness of IgG4 as a marker of efficacy of steroid treatment, a decrease in the serum concentrations of IgG4 was found in the four available studies. The serum IgG4 subclass is a good marker of AIP, and its determination should be included in the diagnostic workup of this disease. However, the heterogeneity of the studies published until now means that more studies are necessary in order to better evaluate the true accuracy of IgG4 in discriminating AIP versus other autoimmune diseases.

Isocitrate dehydrogenase of Helicobacter pylori potentially induces humoral immune response in subjects with peptic ulcer disease and gastritis

Background

H. pylori causes gastritis and peptic ulcers and is a risk factor for the development of gastric carcinoma. Many of the proteins such as urease, porins, flagellins and toxins such as lipo-polysaccharides have been identified as potential virulence factors which induce proinflammatory reaction. We report immunogenic potentials of isocitrate dehydrogenase (ICD), an important house keeping protein of H. pylori.

Methodology/Principal Findings

Amino acid sequences of H. pylori ICD were subjected to in silico analysis for regions with predictably high antigenic indexes. Also, computational modelling of the H. pylori ICD as juxtaposed to the E. coli ICD was carried out to determine levels of structure similarity and the availability of surface exposed motifs, if any. The icd gene was cloned, expressed and purified to a very high homogeneity. Humoral response directed against H. pylori ICD was detected through an enzyme linked immunosorbent assay (ELISA) in 82 human subjects comprising of 58 patients with H. pylori associated gastritis or ulcer disease and 24 asymptomatic healthy controls. The H. pylori ICD elicited potentially high humoral immune response and revealed high antibody titers in sera corresponding to endoscopically-confirmed gastritis and ulcer disease subjects. However, urea-breath-test negative healthy control samples and asymptomatic control samples did not reveal any detectable immune responses. The ELISA for proinflammatory cytokine IL-8 did not exhibit any significant proinflammatory activity of ICD.

Conclusions/Significance

ICD of H. pylori is an immunogen which interacts with the host immune system subsequent to a possible autolytic-release and thereby significantly elicits humoral responses in individuals with invasive H. pylori infection. However, ICD could not significantly stimulate IL8 induction in a cultured macrophage cell line (THP1) and therefore, may not be a notable proinflammatory agent.

Is there anything to the reported association between Helicobacter pylori infection and autoimmune thyroiditis?

Higher serological prevalence rates of Helicobacter pylori (Hp) infection have been reported in patients with autoimmune thyroiditis (AT), and it has been suggested that monoclonal antibodies against Cag-A positive Hp strains can cross-react with follicular cells of the thyroid gland. We studied the prevalence of AT and thyroid functional status in patients who underwent gastroscopy for dyspeptic symptoms. Patients were tested for TSH, free thyroid hormones, and antithyroglobulin and antithyroperoxidase antibodies (ATPO). Hp positivity was determined using urea breath test (UBT). Serum samples from 302 patients (59.9% women) were evaluated. One hundred ninety-one subjects (63.2%) were Hp-negative, and 111 of 302 (36.8%) were Hp-positive. Forty-three of 191 Hp-negative patients (22.5%; 95% CI, 17.1-29.0%) had an increase of either antibody, compared to 30 of 111 (27.0%; 95% CI, 19.6-36.0%) Hp-positive patients (P = 0.40). Similar results were obtained using positivity for both antibodies (7.3 vs. 7.2%; P = 1) or for ATPO (18.8 vs. 21.6%; P = 0.54). The prevalences of hypothyroidism (4.7 vs. 5.5%) or hyperthyroidism (5.8 vs. 5.5%) were also similar (P = 0.95). Hormonal levels were not different in the two groups (P > 0.22 in all cases). The previously reported association between AT and Hp infection was not observed in our study. Infection by Hp does not appear to increase the risk of AT in individuals with dyspeptic symptoms, and screening for this condition in patients with a positive UBT is not indicated.

Influence of daily low-dose 14-membered-ring macrolide therapy on Helicobacter pylori infection in patients with chronic inflammatory disease of the airway

Our aim was to evaluate the effects of eradication and the incidence of secondary resistance by long-term low-dose daily 14-membered-ring macrolide therapy on Helicobacter pylori ( H. pylori) infection in patients with chronic lower respiratory tract inflammatory disease. In a retrospective analysis, we studied the seroprevalence of H. pylori IgG in 90 patients with inflammation of the lower respiratory tract (68 had been treated with macrolide and 22 served as controls). Then, in a prospective analysis, we evaluated the eradication effect of macrolide therapy by the decline of IgG values and the (13)C-urea breath test. Only long-term macrolide use significantly affected the seroprevalence of H. pylori IgG. However, macrolide therapy did not reduce the H. pylori IgG values in 24 patients and did not eradicate H. pylori in (13)C-urea breath tests. Chemosensitivity testing was performed on three H. pylori strains obtained by gastric biopsy from patients in whom the disease could not be eradicated. Only one strain demonstrated a resistant character. Daily long-term low-dose 14-membered-ring macrolide therapy for patients with lower respiratory inflammatory disease may not be sufficient to eradicate H. pylori, but some strains do not acquire a resistant nature.

IgG antibodies against microorganisms and atopic disease in Danish adults: the Copenhagen Allergy Study

BACKGROUND

Seropositivity to food-borne and orofecal microorganisms (hepatitis A virus, Helicobacter pylori, and Toxoplasma gondii ), which are considered to be markers of poor hygiene, has been reported to be associated with a lower prevalence of atopy. In contrast, colonization of the gut with Clostridium difficile, a potential intestinal bacterial pathogen, in early childhood may be associated with a higher prevalence of atopy.

OBJECTIVE

The objective of this study was to investigate the association between atopy and exposure to 2 groups of food-borne and orofecal microorganisms: (1) markers of a poor hygiene and (2) intestinal bacterial pathogens.

METHODS

A cross-sectional population-based study of 15- to 69-year-olds living in Copenhagen, Denmark, was carried out in 1990 to 1991. Atopy was defined as a positive test result for specific IgE to at least 1 of 6 inhalant allergens. Exposure to microorganisms was assessed as IgG seropositivity to microorganisms.

RESULTS

Seropositivity to 2 or 3 markers of poor hygiene (hepatitis A virus, H pylori, and T gondii ) was associated with a lower prevalence of atopy (adjusted odds ratio, 0.5; 95% CI, 0.3 to 0.8). In contrast, seropositivity to 2 or 3 intestinal bacterial pathogens (C difficile, Campylobacter jejuni, and Yersinia enterocolitica ) was associated with a higher prevalence of atopy (adjusted odds ratio, 1.7; 95% CI, 1.2 to 2.6).

CONCLUSION

Exposure to markers of poor hygiene was associated with a lower prevalence of atopy, whereas exposure to intestinal bacterial pathogens was associated with a higher prevalence of atopy. These findings raise the hypothesis that different groups of food-borne and orofecal microorganisms may have different effects on the risk of atopy.

Detection of specific Helicobacter pylori DNA and antigens in stool samples in dyspeptic patients and healthy subjects

In this study stool samples from dyspeptic patients and healthy subjects were used for detection of specific Helicobacter pylori antigens and DNA by immunoenzymatic test (PPHpSA) and semi-nested PCR (ureA-PCR), respectively. The H. pylori status was estimated by invasive endoscopy-based rapid urease test and histology or noninvasive urea breath test (UBT), and by serology (ELISA, Western blot). The coincidence of H. pylori-negative invasive tests or UBT and negative antigen or DNA stool tests was very high (mean 95%). The PPHpSA results were found positive for 56% and ureA-PCR for 26% of individuals with H. pylori infection confirmed by invasive tests or UBT. The detection of specific H. pylori antigens and especially DNA in feces is not sufficient as a one-step diagnosis of H. pylori infection.

Ecological and immunopathological implications of oral bacteria in Helicobacter pylori-infected disease

Increasing evidence has linked colonization by Helicobacter pylori with the development of gastritis and peptic ulcer disease. H. pylori resides primarily in the gastric mucosa without invading the gastric epithelium, causing persistent mild gastric inflammation. There are many reports examining the relationship between colonization by microorganisms in the stomach and oral cavity. We found that some oral bacteria are able to trap H. pylori cells, but oral bacteria inhibit H. pylori growth in vitro. In cases where H. pylori was detected in oral cavity samples, including oral cancer surface samples, we suggested that this species had colonized the stomach and were present in the oral cavity only as a transient organism. We demonstrated that periodontopathic Campylobacter rectus strains posses proteinaceous antigens, including heat shock proteins that share antigenicity with antigens of H. pylori strains. These cross-reactive antigens between H. pylori and C. rectus may be related to the induction of immunopathological responses in periodontal tissues and the stomach. We concluded that H. pylori could not survive in the human oral cavity; however, there would be an interrelationship between periodontal disease due to C rectus and stomach diseases due to H. pylori.

[Evaluation of enzyme-linked immunosorbent assay for the diagnosis of Helicobacter pylori infection in children and adolescents]

BACKGROUND

Helicobacter pylori infection is recognized as the most frequent cause of chronic gastritis in adults and children. The diagnosis is accomplished with invasive methods in fragments of endoscopic gastric biopsies and non-invasive methods. The enzyme-linked immunosorbent assay constitutes a simple, fast exam and of low cost with high sensibility in adult patients.

AIM

The purpose of this study was to evaluate the ELISA method for the infection diagnosis for Helicobacter pylori in children and adolescents using the Cobas Core II kit (Roche). Helicobacter pylori was positive when the rapid urease test and the histology were both positive or when the culture was positive and Helicobacter pylori negative when all the tests were negative.

PATIENTS/METHODS

Eleven hundred patients were studied, their age ranged from 3 months and 16 years, (mean = 8y 7m +/-; 4.0; median = 9y 5m). Helicobacter pylori infection was diagnosed in 47.7% (53/111).

RESULT

Sensitivity was 83.0% and 86.0%; specificity was 70.6% and 71.0%, using the cutoff of 7 U/mL and 5 U/mL, respectively. When only the positive culture was used as gold standard and the cutoff of 5 U/mL, the sensitivity was 93.3%. In patients older than 10 years, the sensibility was 90.6% and 96.8%; specificity was 71.0% and 61.9%, with the cutoff of 7 U/mL and 5 U/mL, respectively.

CONCLUSION

ELISA method had good sensitivity in children older than 10 years, using the cutoff 5 U/mL, but the specificity was low.

Novel antigens of Helicobacter pylori correspond to ulcer-related antibody pattern of sera from infected patients

Recently, we reported that the patterns of antibodies to Helicobacter pylori protein antigens in serum may be useful for screening patients at high risk for ulcers (P. Aucher et al., J. Clin. Microbiol. 36:931-936, 1998). Here we report the identification, by a combination of electrophoretic, immunochemical, and protein sequencing methods, of five antigens that correspond to this antibody pattern: groEL, catalase A, flagellin A, beta-ketoacyl-acyl carrier protein synthase I (beta-ketoacyl-ACP S), and peptidyl prolyl cis-trans isomerase (PPiase). Beta-Ketoacyl-ACP S and PPiase are reported for the first time as antigens of diagnostic interest in infections by H. pylori. The antigenicity of the five antigens, together with those of CagA and VacA, was tested in an immunoblot assay with water-soluble protein extracts from two H. pylori pathogenic strains (HP 141 and ATCC 43579) and panels of sera from H. pylori-positive patients with gastroduodenal ulcers (GDU), nonulcer dyspepsia (NUD), as well as sera from H. pylori-negative healthy volunteers. For catalase A, groEL, and flagellin A antigens, no overall statistically important values were found making it possible to discriminate between patients with GDU and NUD. For both H. pylori strains, the mean performance indices (MPI) presenting percentages of correctly classified patients with GDU and NUD showed that the most significant antibody patterns were as follows: anti-VacA + anti-beta-ketoacyl-ACP S (MPI = 76.1), anti-VacA + anti-PPiase (MPI = 71.8), and anti-CagA + anti-VacA + anti-beta-ketoacyl-ACP S (MPI = 70.5). Antibody patterns detected with these antigen profiles may therefore be useful in developing a diagnostic test designed to predict the clinical severity of the H. pylori infection within the adult population of France.

Shared antigenicity between Helicobacter pylori and periodontopathic Campylobacter rectus strains

Periodontopathic Campylobacter rectus strains possess 41- and 68-kDa proteinaceous antigens which share antigenicity with antigens of Helicobacter pylori strains. H. pylori strains have a 54-kDa antigen which reacts with C. rectus strains. We found that the salivary IgA levels against H. pylori were correlated with those against C. rectus. These cross-reactive antigens of C. rectus may affect the serological diagnosis of H. pylori infections, especially when saliva is used. It is possible that these cross-reacting antigens may relate to the induction of immunopathological responses against both microorganisms.

The accuracy of serologic diagnosis of Helicobacter pylori infection in school-aged children of mixed ethnicity

The present study evaluated two non-invasive diagnostic methods for H. pylori infection in children, i.e. an in-house ELISA using sonicated Campylobacter jejuni antigen for absorption of cross-reacting antibodies and an immunoblot kit (Helico Blot 2.0, Genelabs, Singapore). 13C -Urea breath test (13C-UBT) was used as reference

METHOD

Sera and questionnaires were collected from 695/858 (81%) Swedish school children with mixed ethnic backgrounds within a cross-sectional, community-based study. Of 133 children with an ELISA OD value of > or = 0.1, all were screened with immunoblot and 107 made a 13C-UBT. The negative controls were 34/37 children from three school classes with an ELISA OD value of < 0.1 and volunteering for a 13C-UBT. An adjusted cut-off level for the ELISA of OD value 0.22 resulted in a sensitivity of 97.8%, a specificity of 95.8% and a concordance index of 97.2%. The Helico Blot 2.0 had a sensitivity of 97.8%, a specificity of 93.8% and a concordance index of 96.5%. The best concordance was seen for the 26.5 kDa (98.6%), 30 kDa (95.7%) and 19.5 kDa (91.5%) antigens. The corresponding concordance index for CagA was 78%, for VacA 73.8% and for the 35kDa antigen 68.8%. A significant difference in the distribution of the 19.5 and 26.5 kDa bands but not of CagA/VacA was noted by ethnic background. With an adjusted cut-off level for the enzyme-linked immunosorbent assay (ELISA), both non-invasive methods were found to have an adequate performance in a pediatric population. The differences in antibody response patterns by ethnic background represent a caveat in the interpretation of serological studies.

Differences in genotypes of Helicobacter pylori from different human populations

DNA motifs at several informative loci in more than 500 strains of Helicobacter pylori from five continents were studied by PCR and sequencing to gain insights into the evolution of this gastric pathogen. Five types of deletion, insertion, and substitution motifs were found at the right end of the H. pylori cag pathogenicity island. Of the three most common motifs, type I predominated in Spaniards, native Peruvians, and Guatemalan Ladinos (mixed Amerindian-European ancestry) and also in native Africans and U.S. residents; type II predominated among Japanese and Chinese; and type III predominated in Indians from Calcutta. Sequences in the cagA gene and in vacAm1 type alleles of the vacuolating cytotoxin gene (vacA) of strains from native Peruvians were also more like those from Spaniards than those from Asians. These indications of relatedness of Latin American and Spanish strains, despite the closer genetic relatedness of Amerindian and Asian people themselves, lead us to suggest that H. pylori may have been brought to the New World by European conquerors and colonists about 500 years ago. This thinking, in turn, suggests that H. pylori infection might have become widespread in people quite recently in human evolution.

Seroprevalence of Helicobacter pylori infection in cystic fibrosis and its cross-reactivity with anti-pseudomonas antibodies

BACKGROUND

The prevalence of Helicobacter pylori infection and its role in gastroduodenal disease in cystic fibrosis (CF) are controversial. Additionally, serologic determination of infection in this population may be inaccurate because of cross-reactivity with other bacterial species. The seroprevalence of H. pylori in a cohort of patients with CF and its cross-reactivity with Pseudomonas antibodies were investigated.

METHODS

A research enzyme-linked immunosorbent assay (ELISA), and three commercial serologic assays (PyloriStat; BioWhittaker, Walkersville, MD, U.S.A.; Flexsure; SmithKline Diagnostics, Inc., San Jose, CA, U.S.A.; and HM-CAP; EPI, Stony Brook, NY, U.S.A.) at three independent laboratories determined the seroprevalence of anti-H. pylori IgG antibodies in 70 patients with CF. Cross-reactivity between solid-phase H. pylori antigens and Pseudomonas antibodies was ascertained by a competitive inhibition assay, preadsorbing sera of patients with CF with whole cell proteins from different Pseudomonas species, and serum reanalysis by each assay. Western blot analysis before and after adsorption was performed to identify potential cross-reactive antigens.

RESULTS

The research ELISA, Flexsure, Pyloristat, and HM-CAP initially showed H. pylori seropositivity of 47%, 28%, 24%, and 37%, respectively. Postadsorption seropositivity declined to 8%, 0%, 0%, and 15%, respectively. All patients with research ELISA true-positive results were confirmed endoscopically to have H. pylori infection. Western blot analysis showed a 31-kDa H. pylori protein with antigenic epitopes common to both bacterial species.

CONCLUSIONS

Cross-reactivity between solid-phase H. pylori antigens and anti-Pseudomonas antibodies occurs in patients with CF. A high index of suspicion should be assumed in evaluating results of serologic H. pylori tests in this population. Preadsorption of CF sera with Pseudomonas proteins should be used in serologic testing.

Immunogens of interest for the diagnosis of Campylobacter jejuni infections

In order to identify the C. jejuni immunogens of interest for the diagnosis of Campylobacter infections, we analyzed the humoral response of 153 patients by using complement fixation (CF) and western blot assays. A first group of 79 sera was from C. jejuni infected patients suffering from enteritis (n=16), Guillain-Barré syndrome (GBS) (n=40) and arthritis (n=23). A second group of 49 sera was from healthy blood donors and a third group consisted of 25 sera from children under 4 years old. Using the CF test, 88.6% of the C. jejuni infected patients were seropositive versus 28.5% of the healthy blood donors and none of the children. The Western blot assay allowed detection of antibodies directed against seven selected antigens ranging from 14 to 67 kDa. Three of these antigens with a molecular size of 29, 37 and 43 kDa were detected by 86.0%, 84.8% and 91.1% of the C. jejuni infected patients, respectively. These three antigens seem to be good candidates for the development of assays suitable for direct and indirect diagnosis of Campylobacter infections.

Immunoblotting and serology for diagnosis of Helicobacter pylori infection in children

BACKGROUND

The easiest way to identify the presence of current or past Helicobacter pylori infection is to test for antibodies. The aim of this study was to compare an enzyme-linked immunosorbent assay (ELISA) technique based on the detection of IgG antibodies directed against a global antigenic preparation with immunoblotting based on the analysis of IgG antibody reactivity to separate proteins.

METHODS

Sera were collected from 80 children (mean age, 9.9 +/- 4.3 years). The reference tests were microbiologic and histologic examination of gastric biopsies obtained at upper endoscopy.

RESULTS

The immunoblotting was more sensitive (100%) and specific (88%) than ELISA (96 and 79%, respectively) in the evaluation of H. pylori infection in children. Its positive predictive value was 92%, and its negative predictive value was 100%. The best performance index of immunoreactive bands to detect antibodies was obtained with the 26-kDa (88.7%), 30-kDa (77.5%) and 19.5-kDa (70%) antigens. Antibodies by immunoblot technique against the CagA antigen were present in 43.1% of children.

CONCLUSION

Immunoblotting is highly sensitive and more specific than ELISA in children and provides additional information about the full serologic profile. Immunoblotting may therefore be a useful complement to serology, particularly in cases with doubtful ELISA results.

Serological discrimination of dogs infected with gastric Helicobacter spp. and uninfected dogs

Characterization of the humoral immune responses of people to Helicobacter pylori infection has facilitated the investigation of the host response to bacterial virulence factors and the development of sensitive and specific diagnostic tests. Dogs are commonly infected with gastric Helicobacter spp., but the presence of multiple Helicobacter spp. and possible coinfection in individual dogs have complicated serological evaluation. Evaluation of the antigenic homology of Helicobacter spp. revealed that the major protein bands of Helicobacter felis and Helicobacter bizzozeronii, two Helicobacter spp. that infect dogs, were very similar to UreA (29 to 31 kDa), UreB (63 to 66 kDa), and HSP (58 to 60 kDa) of H. pylori, and sera from infected and uninfected dogs bound in a similar way to each antigen. Immunoblotting and an enzyme-linked immunosorbent assay (ELISA) with H. felis ATCC 49179 antigen were performed with 101 serum samples (from 78 infected dogs and 23 uninfected dogs). Samples from uninfected dogs (median = 8) had fewer bands on immunoblotting than samples from infected dogs (median = 16) (P < 0.05). Combinations of the presence of any two of the low-molecular-mass bands (19, 25, 30, 32, and 37 kDa) or the high-molecular-mass bands (86 and 94 kDa) were found almost solely in samples from infected dogs (P < 0.0001). Kinetic ELISA results were significantly higher for samples from infected dogs (median = 0. 0802 optical density unit [OD]/min) than for samples from uninfected dogs (median = 0.01428 OD/min). The combination of ELISA and immunoblotting results gave a specificity of 95.6% and a sensitivity of 79.8%. No correlation between ELISA results, colonization density, degree of inflammation, and presence of lymphoid follicles was observed. The results indicate substantial antigenic homology between H. felis, H. pylori, and H. bizzozeronii. The combination of ELISA and immunoblotting was a highly specific and moderately sensitive indicator of infection. The degree of seropositivity assessed by ELISA was not related to bacterial colonization density, the degree of gastric inflammation, or the presence of lymphoid follicles.

Blood tests in the management of Helicobacter pylori infection. Italian Helicobacter pylori Study Group

There are three main types of blood test available for the management of Helicobacter pylori infection: those that detect an antibody response; tests of the pathophysiological state of the stomach; and those that indicate an active infection. Enzyme linked immunosorbent assay (ELISA) based kits are the most numerous of the commercially available tests. Originally the kits used crude antigen preparations but many of the newer kits use a more purified antigen preparation giving increased specificity but a lower sensitivity. The sensitivity, specificity, and predictive values of the tests can also be affected by the population under test and coexistent disease in the patients. Near patient test kits are based on either latex agglutination or immunochromatography. Generally, they have low sensitivities compared with laboratory tests. Commercial western blotting kits have also been developed and are used to detect the presence of specific virulence markers. The exact role of serology in the management of Helicobacter infection has still to be defined, although there is evidence that, used as a screening procedure, it can reduce endoscopy cost and workload. Gastrin and pepsinogen blood concentrations may provide valuable information on the pathophysiological state of the stomach--for example, the presence of inflammation or gastric atrophy. A combination of serology and serum concentrations of gastrin and pepsinogen may be used effectively to detect serious gastroduodenal disease in patients.

Antibodies against Helicobacter pylori in feces and saliva before and after eradication therapy

OBJECTIVE: To determine specific antibody levels against Helicobacter pylori antigens in stool and saliva specimens from H. pylori-infected subjects and seronegative controls. METHODS: Antibody levels against a total membrane preparation (MP) and purified flagellin from H. pylori were measured by enzyme-linked immunosorbent assays (ELISAs) in fecal extracts (FEs) and sera from 21 H. pylori-infected and 17 non-infected adult Swedish volunteers; specific antibody levels in saliva (IgG and IgA titers) were also measured in the majority of them. Follow-up specimens after successful eradication of H. pylori were collected after 5--7 weeks (all specimens) and 5 months (FEs and sera). RESULTS: Geometric mean specific IgA antibody levels, adjusted to total IgA concentration, in FEs were significantly higher (p<0.05) in the H. pylori-infected than in the control group against MPs (p<0.05) and flagelin (p<0.05). The total IgA concentrations in FEs from infected and seronegative controls were comparable and the IgA was mainly of the secretory type. Saliva specimens from H. pylori-infected subjects had higher ELISA IgA than IgG titers against MP. Anti-MP antibodies of both isotypes were higher in the infected than in the non-infected group (p<0.05 for both isotypes). The total IgA levels were also significantly (p<0.05) higher in saliva from the H. pylori-infected subjects than in saliva from the controls (geometric mean 292 mg/L and 173 mg/L, respectively). Eradication therapy resulted in a more rapid decline in antibody levels in FEs than in corresponding sera or saliva specimens. CONCLUSIONS: Specific antibodies against H. pylori MP were detected in FEs as well as in saliva from most of the infected volunteers, the mean antibody levels being significantly higher in specimens from the H. pylori-infected subjects than from seronegative controls. The results suggest that analyses of antibody levels in FEs may be used for follow-up of patients early (5--7 weeks) after onset of successful eradication therapy.

An analysis of seven different methods to diagnose Helicobacter pylori infections

BACKGROUND

It has been debated which diagnostic test should be preferred for the diagnosis of Helicobacter pylori in patients with gastroduodenal diseases.

METHODS

The H. pylori infection was diagnosed prospectively in 97 untreated patients. H. pylori was diagnosed by means of tests based on five different principles: 1) culture, 2) microscopy (HLO), 3) urease activity (urea breath test (UBT) and urease test on biopsy specimens (CLO test)), 4) DNA detection (polymerase chain reaction (PCR)), and 5) IgG antibody detection (enzyme-linked immunosorbent assay (EIA) and Western blotting (WB)).

RESULTS

This study showed that two positive tests out of five tests, based on different principles, were most reliable for predicting the H. pylori infection. Most tests had specificities and predictive values for a negative result greater than 90%. The most important difference between the tests was the sensitivity and the predictive value for a positive result (PPV). WB, HLO, UBT, and PCR had sensitivities and PPV greater than 75%.

CONCLUSIONS

The non-invasive tests UBT and WB are reliable, both alone and in combination, and they are recommended for the pre-endoscopic diagnosis of H. pylori. WB is recommended as a confirmative test for antibody detection by EIA. When patients have an upper endoscopy, we recommend taking biopsy specimens for culture and histology because of the additional information obtained about susceptibility, virulence determinants, and morphology, including the degree of inflammation.

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.

Detection of serum antibodies to CagA and VacA and of serum neutralizing activity for vacuolating cytotoxin in patients with Helicobacter pylori-induced gastritis

Thirty patients with dyspepsia, with histological diagnosis of gastritis, and with endoscopic diagnosis of peptic ulcer disease (PUD) (n = 13) or nonulcer dyspepsia (NUD) (n = 17) were admitted to the study. Helicobacter pylori vacuolating cytotoxin-producing strains (Tox+) were isolated from 14 (46.7%) patients, whereas non-cytotoxin-producing (Tox-) H. pylori strains were isolated from the remaining patients. Of 30 patients studied, 20 (66.7%) had serum cytotoxin neutralizing activity in vitro. Fourteen patients with Tox+ H. pylori strains showed serum cytotoxin neutralizing activity and serum immunoglobulin G (IgG) and IgA antibodies reactive with both 87-kDa H. pylori vacuolating cytotoxin (VacA) and 128-kDa cytotoxin-associated gene product (CagA) by immunoblotting using native enriched preparations of VacA and CagA proteins from H. pylori culture supernatants as the antigens. A 94-kDa antigen cross-reacting with the 87-kDa VacA protein could be demonstrated in culture supernatant with immune sera from humans and animals. All patients (n = 10) lacking serum neutralizing activity were also negative for IgG or IgA against VacA antigen, whereas 6 of the 10 patients showed IgG serum antibody responses against CagA antigen. The prevalence of antibodies to VacA and CagA antigens was significantly (P < 0.001) higher in patients with gastritis (20 and 26 patients for VacA and CagA, respectively, of 30 patients) than in H. pylori culture-negative controls (0 of 27 for both VacA and CagA) and in randomly selected blood donors (17 and 21 for VacA and CagA, respectively, of 120 subjects). All patients with PUD had antibodies to CagA, whereas 13 of 17 (76.5%) patients with NUD had anti-CagA antibodies. Serum IgG antibodies to VacA were present in 9 (69.2%) patients with PUD of 13 patients and in 11 (64.7%) patients with NUD of 17 patients. Anti-CagA antibodies seemed to correlate better with PUD than anti-VacA antibodies.

Helicobacter pylori acquisition in infancy after decline of maternal passive immunity

We evaluated the natural history of Helicobacter pylori infection and the host immune response in 80 infants, and determined seroprevalence of H. pylori infection in their Taiwanese mothers. Decline in passively transferred maternal anti-H. pylori IgG antibodies and subsequent H. pylori infection was assessed in infants over 14 mo. A sensitive and specific, 96-well microtiter ELISA for the detection of H. pylori IgG antibodies was used to evaluate maternal serum (single specimen) and their infants (birth, 1, 2, 3, 6, 12, and 14 mo). Sera were also evaluated by ELISA for the presence of anti-H. pylori IgM antibodies in the infants. Maternal H. pylori IgG seroprevalence was 62.5% [50/80; 95% confidence intervals (CI), 51-73%]. All infants born to the 50 seropositive mothers passively acquired maternal H. pylori IgG. Transplacentally transferred maternal anti-H. pylori IgG lasted until about the 3rd mo of life, and disappeared in nearly all the infants by 6 mo of age. Seven and one-half percent of infants (6/80; 95% CI, 3-16%) acquired H. pylori infection; two were born to H. pylori-negative mothers. Among the six IgG seropositive infants, an IgM response specific for H. pylori antigens was detected and appeared to precede the rise in IgG in five. We conclude that maternal passive transfer of IgG antibodies occurs in the infant and disappears by 6 mo of age. H. pylori infection is acquired in infancy in this population; IgM antibodies against H. pylori are detectable, seem short-lived, and appear to precede IgG antibody development.

Serological indicators of Helicobacter pylori infection in adult dyspeptic patients and healthy blood donors

The levels of IgM, IgG and IgA antibodies reacting with two Helicobacter pylori antigens (glycine acid extract (GE) and a recombinant CagA protein) were determined in the sera from adult dyspeptic patients, positive (H.p.(+)) or negative (H.p.(-)) for H. pylori urease/culture, and from healthy blood donors. All sera were also examined against GE by Western blot (Immunoblot) technique. Similar levels of anti-GE IgG were detected in the sera from all H.p.(+) and almost all H.p.(-) patients and from over 40% of the healthy volunteers. In contrast, higher levels of anti-GE IgA were found in the sera from patients than that from healthy subjects, although such antibodies were not detected in the sera from 30% of the H.p.(+) patients. In general, our results suggest that a combination of ELISA and immunoblot may be more sensitive in the detection of H. pylori infection in dyspeptic patients than the examination of biopsy specimens by culturing or histology.

Evaluation of three commercial enzyme immunoassays compared with the 13C urea breath test for detection of Helicobacter pylori infection

The diagnostic significance of the serological detection of antibodies to Helicobacter pylori has been established by numerous investigators. Reports of the clinical reliabilities of commercial enzyme immunoassay (EIA) kits available for this purpose vary as a result of the different H. pylori antigen sources and reference methods used. The 13C urea breath test (UBT) has been shown to be an extremely accurate and reliable method of detecting H. pylori infection. We used the 13C urea breath test as the confirmatory method for H. pylori status to evaluate three commercially available EIA kits designed to detect immunoglobulin G antibodies to H. pylori. These kits were the HM-CAP EIA kit (Enteric Products, Inc.), the PYLORI STAT EIA kit (BioWhittaker, Inc.), and the G.A.P. kit (Bio-Rad Laboratories/Biomerica, Inc.). The evaluations were performed in a double-blind manner with samples from 473 clinically characterized patients. This group included patients with symptomatic gastrointestinal disorders as well as nonsymptomatic volunteers. The sensitivities of the kits were as follows: HM-CAP, 98.4%; PYLORI STAT, 99.2%; and G.A.P., 100%. The specificities were as follows: HM-CAP, 96.4%; PYLORI STAT, 90.1%; and G.A.P., 26.0%. Although the HM-CAP and PYLORI STAT kits performed comparably, the G.A.P. test yielded significantly more false-positive results and an unacceptably high number of indeterminate results.

Isolation and preliminary evaluation of a low-molecular-mass antigen preparation for improved detection of Helicobacter pylori immunoglobulin G antibodies

Previously, immunoglobulin G (IgG) antibodies to five antigens with a relative molecular mass of between 15 and 30 kDa from Helicobacter pylori were found to be significantly more frequent in H. pylori-infected patients than in noninfected patients. In this study, these specific low-molecular-mass (LMW) antigens were separated by ultrafiltration of whole-cell sonicates. The LMW antigen preparation was evaluated by enzyme-linked immunosorbent assay with serum samples from 76 children with abdominal symptoms and 151 adults with dyspeptic symptoms. H. pylori was cultured or seen in 40 (53%) children and 83 (55%) adults. Increased antibody levels to H. pylori were found in serum from 35 (46%) children and 88 (58%) adults. Values for sensitivity, specificity, and predictive value of positive and negative results of the test were higher with LMW antigens than with the heat-stable antigen previously described. The low specificity and predictive value of a positive result were due to seropositive results for 21 persons with a negative culture for H. pylori and negative microscopy results for Helicobacter-like organisms in biopsies from gastric mucosa. Histologically, chronic gastritis was demonstrated in 43% of these persons, and 19% had peptic ulcer, indicating that they have or have had H. pylori infection. Specific antibodies to H. pylori were confirmed in all 21 patients by the Western immunoblot technique. Use of the LMW antigen improved the IgG antibody detection in patients with H. pylori infection, even though the results reflect the difficulties in establishing a true gold standard for diagnosis of H. pylori infection.