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

Non-invasive diagnostic tests for Helicobacter pylori infection

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Accuracy of the serum intestinal fatty-acid-binding protein for diagnosis of acute intestinal ischemia: a meta-analysis

Numerous studies have investigated the utility of serum intestinal fatty-acid binding protein (I-FABP) in differentiating acute intestinal ischemia from acute abdomen. However, the results remain controversial. The aim of this meta-analysis is to determine the overall accuracy of serum I-FABP in the diagnosis of acute intestinal ischemia. Publications addressing the accuracy of serum I-FABP in the diagnosis of ischemic bowel diseases were selected from databases. The values of true-positive (TP), true-negative (TN), false-positive (FP), and false-negative (FN) were extracted or calculated for each study. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were calculated. The overall diagnostic performance was assessed using a summary receiver operating characteristic curve (SROC) and area under curve (AUC). Nine studies that collectively included 1246 patients met the eligible criteria. The pooled sensitivity, specificity, DOR, PLR, and NLR were 0.80 (95% CI: 0.72–0.86), 0.85 (95% CI: 0.73–0.93), 24 (95% CI: 9–65), 5.5 (95% CI: 2.8–10.8) and 0.23 (95% CI: 0.15–0.35), respectively. The AUC was 0.86 (95% CI: 0.83–0.89). The meta-analysis carried out in this report suggests that the I-FABP may be a useful diagnostic tool to confirm acute intestinal ischemia in acute abdomen, but better-designed trials are still required to confirm our findings.

Non-Invasive Diagnosis of Helicobacter pylori: Evaluation of Two Enzyme Immunoassays, Testing Serum IgG and IgA Response in the Anand District of Central Gujarat,India

CONTEXT

Validation of an accurate and less cumbersome noninvasive method to detect current Helicobacter pylori infection is a requisite for any laboratory.

OBJECTIVES

The purpose of this study is to corroborate the usefulness of two commercially available kits NovaTec ELISA-A and ELISA-G, in the detection of ongoing H.pylori infection.

MATERIALS AND METHODS

Two hundred and twenty eight consecutive serum samples of symptomatic patients who attended the endoscopy unit of "Deep" surgical hospital, Anand, which were collected during the period from 27th February 2008 to 31st august 2011, were studied. The sera were processed and tested for the detection of the H.pylori IgG and IgA antibody by using a solid phase; capture micro well ELISA, procured from Nova Tec immunodiagnostica GmbH Germany.

RESULTS

IgG ELISA showed 100% sensitivity and Negative predictive value (NPV), while IgA ELISA was better in terms of specificity (61.4%) and accuracy (63%) as compared to IgG ELISA. We found 7% (16/228) of IgA positive cases with IgG negative response. IgG response was more common in reflux esophagitis patients (OR 1.451, 95%CI-0.850-2.477) and then in gastritis (OR 0.962, 95%CI-0.570-1.621) and duodenitis(OR-0.806, 95%CI-0.112-5.827), while IgA positive response was more common in duodenitis patients (OR-1.383, 95%CI-0.191-9.995) and reflux esophagitis patients (OR 1.289, 95% CI-0.756-2.197) and least in duodenal ulcer patients (OR 0.670, 95%CI-0.222-2.029).

CONCLUSION

IgG update is reliable and accurate test and can be expedient as a screening test and thus serve as an alternative to endoscopy. For the purpose of excluding infection with H.pylori, the performance of IgG is moderate (low specificity) but can be improved by conjunctional IgA testing which will offer some additional diagnostic value.

Assessment of Helicobacter pylori eradication in patients on NSAID treatment

Background

In this post-hoc analysis of a randomized, double blind, placebo controlled trial, we measured the sensitivity and specificity of Helicobacter pylori IgG-antibody titer changes, hematoxylin and eosin (H&E) stains, immunohistochemical (IHC) stains and culture results in NSAID using patients, following H. pylori eradication therapy or placebo.

Methods

347 NSAID using patients who were H. pylori positive on serological testing for H. pylori IgG-antibodies were randomized for H. pylori eradication therapy or placebo. Three months after randomization, gastric mucosal biopsies were taken for H. pylori culture and histological examination. At 3 and 12 months, blood samples were taken for repeated serological testing. The gold standard for H. pylori infection was based on a positive culture or both a positive histological examination and a positive serological test. Sensitivity, specificity and receiver operating curves (ROC) were calculated.

Results

H. pylori eradication therapy was successful in 91% of patients. Culture provided an overall sensitivity of 82%, and 73% after eradication, with a specificity of 100%. Histological examination with either H&E or IHC stains provided sensitivities and specificities between 93% and 100%. Adding IHC to H&E stains did not improve these results. The ROC curve for percent change in H. pylori IgG-antibody titers had good diagnostic power in identifying H. pylori negative patients, with an area under the ROC curve of 0.70 (95 % CI 0.59 to 0.79, P = 0.085) at 3 months and 0.83 (95% CI 0.76 to 0.89, P < 0.0001) at 12 months. A cut-off point of at least 21% decrease in H. pylori IgG-antibody titers at 3 months and 58% at 12 months provided a sensitivity of 64% and 87% and a specificity of 81% and 74% respectively, for successful eradication of H. pylori.

Conclusions

In NSAID using patients, following H. pylori eradication therapy or placebo, histological examination of gastric mucosal tissue biopsies provided good sensitivity and specificity ratios for evaluating success of H. pylori eradication therapy. A percentual H. pylori IgG-antibody titer change has better sensitivity and specificity than an absolute titer change or a predefined H. pylori IgG-antibody titer cut-off point for evaluating success of H. pylori eradication therapy.

Correlation of serology with morphological changes in gastric biopsy in Helicobacter pylori infection and evaluation of immunohistochemistry for H. pylori identification

BACKGROUND/AIM

Helicobacter pylori is implicated in various gastroduodenal diseases and many tests are available for its detection. The present study attempted to document the morphological changes in the gastric mucosa induced by H. pylori colonization and correlate them with the severity of the infection. The study also compared various diagnostic tests and evaluated the different staining methods used for H. pylori detection, especially immunohistochemical identification.

PATIENTS AND METHODS

One hundred and two patients with dyspepsia were included. Enzyme-linked immunosorbent assay (ELISA) for H. pylori-specific immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin M (IgM) was used. Rapid urease test was performed on endoscopic biopsy and it was stained with hematoxylin and eosin (H and E), modified Giemsa, and immunohistochemical stains.

RESULTS

A significant correlation was found between the density of H. pylori and severity of gastritis. A significant correlation was observed between serology (especially when used in combination, IgG and IgA) and status of H. pylori. Immunohistochemical staining enhanced the diagnostic yield of H. pylori detection.

CONCLUSIONS

Immunohistochemistry (IHC) should be used judiciously, whereas simple and economical tests like modified Giemsa should be used routinely for the detection of H. pylori. Combined ELISA (IgG and IgA) should be preferred over single ELISA. Simultaneous morphological and serological detection of H. pylori is preferable as H. pylori may not be detected on morphology alone due to its patchy distribution in the stomach.

Efficacy of serology driven "test and treat strategy" for eradication of H. pylori in patients with rheumatic disease in the Netherlands

The treatment of choice of H. pylori infections is a 7-day triple-therapy with a proton pump inhibitor (PPI) plus amoxicillin and either clarithromycin or metronidazole, depending on local antibiotic resistance rates. The data on efficacy of eradication therapy in a group of rheumatology patients on long-term NSAID therapy are reported here. This study was part of a nationwide, multicenter RCT that took place in 2000-2002 in the Netherlands. Patients who tested positive for H. pylori IgG antibodies were included and randomly assigned to either eradication PPI-triple therapy or placebo. After completion, follow-up at 3 months was done by endoscopy and biopsies were sent for culture and histology. In the eradication group 13% (20/152, 95% CI 9-20%) and in the placebo group 79% (123/155, 95% CI 72-85%) of the patients were H. pylori positive by histology or culture. H. pylori was successfully eradicated in 91% of the patients who were fully compliant to therapy, compared to 50% of those who were not (difference of 41%; 95% CI 18-63%). Resistance percentages found in isolates of the placebo group were: 4% to clarithromycin, 19% to metronidazole, 1% to amoxicillin and 2% to tetracycline.

Helicobacter pylori eradication in patients on long-term treatment with NSAIDs reduces the severity of gastritis: a randomized controlled trial

BACKGROUND

Maintenance use of nonsteroidal anti-inflammatory drugs (NSAIDs) is often complicated by gastropathy. In non-NSAID users, eradication of Helicobacter pylori is associated with decreased mucosal inflammation, and may halt the progression to atrophy and intestinal metaplasia, but the continuous use of NSAIDs may interfere with these processes.

GOAL

To investigate the effect of H. pylori eradication on gastric mucosal histology during long-term NSAID use, with and without gastroprotective therapy.

STUDY

Patients were eligible for inclusion if they were on long-term NSAIDs and were H. pylori-positive on serologic testing. Patients were randomly assigned to either eradication or placebo. Gastritis was assessed according to the updated Sydney classification for activity, chronic inflammation, gastric glandular atrophy, intestinal metaplasia, and H. pylori density.

RESULTS

Biopsy specimens were available for histology of 305 patients. Of these, 48% were on chronic gastroprotective medication. Significant less active gastritis, inflammation, and H. pylori density was found in the eradication group compared with the placebo group in both corpus and antrum (P<0.001). In the corpus, less atrophy was found in the eradication group compared with the placebo group.

CONCLUSIONS

H. pylori eradication in patients on long-term NSAID therapy leads to healing of gastritis despite ongoing NSAID therapy.

Accuracy of Helicobacter pylori serology in two peptic ulcer populations and in healthy controls

AIM: To estimate the test characteristics of Helicobacter pylori (H pylori) serology and of C14-urea breath test (C14-UBT) in two different peptic ulcer populations and in community controls. Second, the aim was to explore the association between the level of H pylori IgG antibodies and severity of inflammation as to active peptic ulceration in the same populations.

METHODS: Vagotomized (n = 83), medically treated peptic ulcer patients (n = 73) and one reference group of community controls (n = 88) were gastroscoped. H pylori status was determined by histology, bacterial growth, C14-UBT and serology. Based on the updated Sydney System, cumulative scores from biopsies from the prepyloruos, incisura angularis, corpus and fundus were calculated.

RESULTS: The prevalence of H pylori infection varied from 70% to 79%. The C14-UBT had high accuracy compared to the serology test. The sensitivity of the serology test was good, but the specificity was low (41%-71%). The association between H pylori IgG antibodies and scores of gastric mucosal inflammation and current or previous peptic ulcer were weak.

CONCLUSION: The accuracy of C14-UBT to diagnose H pylori infection was good, and the clinical utility of a negative H pylori serology test was substantial, while the gain in clinical information of a positive test was meagre. Positive H pylori titres could not distinguish between subjects with or those without active peptic ulceration.

Eradication of Helicobacter pylori does not reduce the incidence of gastroduodenal ulcers in patients on long-term NSAID treatment: double-blind, randomized, placebo-controlled trial

BACKGROUND

Helicobacter pylori and nonsteroidal antiinflammatory drugs (NSAIDs) are the major causes of gastroduodenal ulcers. Studies on the benefit of eradication of H. pylori in NSAID users yielded conflicting results.

OBJECTIVE

To investigate whether H. pylori eradication in patients on long-term NSAIDs reduces the incidence of gastroduodenal ulcers.

METHODS

Patients on long-term NSAID treatment and who are H. pylori positive on serologic testing, were randomly assigned to either H. pylori eradication (omeprazole, amoxicillin, and clarithromycin) or placebo. Primary endpoint was the presence of endoscopic gastric or duodenal ulcers 3 months after randomization.

RESULTS

One hundred sixty-five (48%) of a total of 347 patients were on gastroprotective medication. At endoscopy, gastroduodenal ulcers were diagnosed in 6 (4%) and 8 (5%) patients in the eradication and placebo group, respectively (p = .65). During follow-up of 12 months, no symptomatic ulcers or ulcer complications developed. No significant differences were found in the development of gastroduodenal erosions, dyspepsia, or in quality of life.

CONCLUSION

H. pylori eradication therapy in patients on long-term NSAID treatment had no beneficial effect on the occurrence of ulcers, erosions, or dyspepsia. Ulcer rates in both study arms are remarkably low, in both patients with and without gastroprotective therapy.

Serum anti-Helicobacter pylori IgA and IgG antibodies in asymptomatic children in Serbia

The aim of this study was to determine the seroprevalence of Helicobacter pylori and the distribution of anti-H.pylori IgA and IgG antibodies in asymptomatic children aged between 7 and 18 y. We studied the serum samples of 283 children using the commercial ELISA test for the detection of anti-H. pylori IgA and IgG antibodies. The overall prevalence of anti-H. pylori antibodies was 36.4%. The seroprevalence was 35%, 28.3%, 37.5%, and 42.2% for the ages of 7, 10, 14 and 18 y, respectively. Serum IgG antibodies alone were detected in 88.3%, IgA alone in 4.9%, and both IgA and IgG antibodies were detected in 6.8% of samples. The mean levels of IgG antibodies to H. pylori increased with age. We concluded that the prevalence of H. pylori antibodies in Serbian children was high (36.4%), ranging from 35% to 42.2%. The detection of IgG antibodies is useful for the determination of seroprevalence in asymptomatic children.

Evaluation of commercial immunoassays for detection of antibody against Helicobacter pylori in Thai dyspeptic patients

The performance of five immunoassays for detection of immunoglobulin G antibody against Helicobacter pylori in 191 dyspeptic patients was evaluated. The sensitivities, specificities, accuracies, positive predictive values, and negative predictive values ranged from 86.32 to 97.89%, 57.95 to 72.22%, 77.02 to 83.76%, 71.54 to 77.42%, and 83.33 to 96.23%, respectively. The immunoglobulin A test kit also gave a high sensitivity and negative predictive value (95.79 and 91.40%, respectively), while the specificity was relatively low (51.14%).

[Seroconversion and seroreversion rate of Helicobacter pylori infection in women attended at hospital for delivery]

BACKGROUND AND OBJECTIVE

Helicobacter pylori infections are acquired primarily during childhood. Nevertheless, infections also develop in the adult population and it is not clear how the cumulative effect of these infections occurs throughout life. With the aim to contribute to the current data on the evolution of H. pylori infection in the adult population of Spain, the incidence and prevalence rates in a population of women who went to the hospital for delivery were studied.

SUBJECTS AND METHOD

The study considered the sero-conversion and sero-reversion of H. pylori antibodies in 1441 women from Gipuzkoa (Basque Country, Spain), between 15 and 41 years-old (mean 28.5 [3.4]). These women delivered after September 1989 and had a second childbirth 2 to 8 years later. A serum sample was obtained at the time of each childbirth. Results were determined by enzymoimmunoanalysis (Pyloriset EIA-G New, Finland).

RESULTS

H pylori antibodies were detected in the first serum specimen of 648 women (45.0% prevalence). Twenty-four out of the 793 women who were initially seronegative underwent a seroconversion in successive years, and an annual infection rate of 0.77% (95% CI 0.49-1.14) was estimated. Twenty-six women, who were initially seropositive, yielded negative result in the second serum specimen, which led to an annual sero-reversion rate of 1.03% (95% CI 0.67-1.50).

CONCLUSIONS

These results suggest that in our environment, infections by H. pylori occur with a moderate frequency in adults. The fact that the sero-reversion rate is similar to or higher than the sero-conversion one suggests that the prevalence of H. pylori infection in the adult population is currently decreasing.

Tumour Necrosis Factor Alpha Antibody Affects Gastrin Release in Crohn Disease

BACKGROUND

Gastrin plays an important role in the regulation of gastric acid secretion in humans. Tumour necrosis factor alpha (TNF-α) stimulates gastrin release from antral G cells in vitro. The aim was to determine whether gastrin release decreases in patients with Crohn disease treated with monoclonal antibody to TNF-α.

METHODS

Twenty-five consecutive patients with Crohn disease (10 M, 15 F; 18 with fistulas) were treated with a single intravenous infusion of the monoclonal antibody to TNF-α, infliximab, at a dose of 5 mg/kg. Basal and bombesin stimulated gastrin was measured after an overnight fast immediately before and 2 weeks after infliximab. Helicobacter pylori status was determined by serology.

RESULTS

Twenty-two patients were H. pylori-negative. Basal plasma gastrin was 21 (16-26) pmol/L before and 19 (15-25) pmol/L after infliximab (NS). Bombesin stimulated gastrin decreased from 49 (40-62) pmol/L before to 36 (33-59) pmol/L (P &lt; 0.005) 2 weeks after infliximab.

CONCLUSION

Gastrin release in response to bombesin decreases in patients with Crohn disease treated with infliximab.

Helicobacter pylori infection as a risk factor for gastrointestinal symptoms in patients using aspirin to prevent ischaemic heart disease

BACKGROUND

Aspirin use in the secondary prevention of ischaemic heart disease may provoke gastrointestinal discomfort.

OBJECTIVE

To register gastrointestinal symptoms and complications in patients with cardiovascular disease using aspirin and to relate these symptoms to infection with H. pylori.

METHODS

Blood samples were obtained from 398 consecutive patients in the Coronary-Care Unit, University Hospital Nijmegen and analysed for serum antibody levels to H. pylori infection. Questionnaires were sent 2 weeks after discharge to assess gastrointestinal symptoms.

RESULTS

Questionnaires were returned by 314 patients (79%). A total of 183 out of 314 patients (46%) reported gastrointestinal symptoms. Of 238 patients using 80-100 mg aspirin daily, 145 (61%) recorded gastrointestinal symptoms. Besides aspirin, the use of calcium antagonists was correlated with gastrointestinal symptoms. Of the 128 patients using calcium antagonists, 84 (66%) reported gastrointestinal symptoms. The prevalence of gastrointestinal symptoms in H. pylori-positive and -negative patients using aspirin was 48% and 52%, respectively.

CONCLUSIONS

Two weeks after discharge almost 50% of the patients with cardiovascular disease experienced gastrointestinal symptoms, especially patients using aspirin or calcium antagonists. Patients seropositive for H. pylori and using aspirin or calcium antagonists did not have more gastrointestinal discomfort compared to non-infected patients.

Long-term follow-up and serologic assessment after triple therapy with omeprazole or lansoprazole of Helicobacter-associated duodenal ulcer

We assessed both the effectiveness of two Helicobacter pylori (Hp) eradication triple therapies and the usefulness of serology in the follow-up. Fifty patients with active or scarred duodenal ulcer were randomized to lansoprazole or omeprazole for 1 to 4 weeks, with clarithromycin 250 mg twice a day and tinidazole 500 mg twice a day for the first week. Endoscopies were scheduled before treatment, after 8 weeks, and after I year. H. pylori status was determined before therapy by rapid urease test and histology and during the follow-up by histology and culture. Serology was determined at baseline and at 6 and 12 months. The regimens were equally effective in inducing ulcer healing (95.8% vs. 87.5%) and eradicating Hp with no recurrences at 12 months. Among 44 patients eradicated, a significant reduction of immunoglobulin G (IgG) titer occurred at 6 (p < 0.0001) and 12 months (p < 0.0001). If a titer reduction of more than 30% was taken as an indicator for Hp eradication, the specificity of enzyme-linked immunosorbent assay was 75% at 6 and 95.4% at 12 months with a 100% sensitivity. Either lansoprazole or omeprazole combined with antibiotics are effective in eradicating Hp. Serology is useful for monitoring Hp eradication provided that an appropriate percent reduction in IgG titer is used after more then 6 months after therapy.

Laboratory tests for the evaluation of Helicobacter pylori infections

Helicobacter pylori is a highly motile bacterium with multiple unipolar flagella, and it produces the urease enzyme. The flagella and urease are the virulence factors of H. pylori. H. pylori often establishes a chronic infection in the stomach that may lead to gastric and duodenal ulcers, gastric cancers, gastric lymphomas, and other gastrointestinal diseases. There are several different invasive and noninvasive clinical laboratory tests for H. pylori. Laboratory testing is not indicated in asymptomatic patients and should be considered only if treatment of H. pylori infection is planned. Invasive tests for H. pylori, such as tissue histology, culture, and rapid urease tests, are used if an endoscopy is performed on the patient. The noninvasive tests for H. pylori, such as enzyme antibody and urea breath tests, are recommended in patients whose symptoms do not warrant endoscopy. The urea breath test is very useful and is recommended to evaluate effectiveness in the eradication and treatment of H. pylori infections. Nucleic acid tests can complement other diagnostic procedures, and are useful in evaluating fixed biopsy tissue, environmental samples, gastric juices, oral secretions, and stool samples.

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

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

Exploring novel vaccines against Helicobacter pylori: protective and therapeutic immunization

Infection of human stomach by Helicobacter pylori, a gram negative spiral bacterium first isolated in 1983 from a patient with chronic active gastritis (1), causes nearly all duodenal ulcers and most gastric ulcers and is associated with an increased risk of gastric adenocarcinoma (2). Current therapies for gastric infections include combination triple or quadruple therapy of antimicrobial and/or antiulcer agents for eradication of H. pylori infection (3). Development of the resistant strains and ecological niche (habitant) of the bacteria may cause relapse after the termination of the therapy. However, if effective, the high cost, difficulty of patient compliance and risk of selection for resistant strains make these therapeutic regimens impractical on a large scale, though effective on the laboratory trial stages. Studies of the pathogenesis of H. pylori have led to the identification of bacterial antigens and adherin proteins as candidates for inclusion as novel vaccines against these diseases (4-7). Both prophylactic and therapeutic vaccination have been demonstrated in animal models of H. pylori infection (8-10).

New immunological assays for the diagnosis of Helicobacter pylori infection

There are several types of immunological tests available for the diagnosis and management of Helicobacter pylori infection. Most commercially available serological kits use the enzyme linked immunosorbent assay (ELISA) test format. Originally the kits used crude antigen preparations although many of the newer kits use a more purified antigen preparation, with often increased specificity but lower sensitivity. Near patient test kits are based either on latex agglutination or immunochromatography. Generally they have low sensitivities compared with laboratory tests. Western blotting, ELISA, and recombinant immunoblot assays (RIBA) have also been developed into commercially available kits and can be used to indicate the presence of specific virulence markers. An antigen detection kit has been developed for the detection of Helicobacter pylori in faeces. Immunological reagents have also been combined with other diagnostic modalities to develop immunohistochemical stains and DNA immunoassays. Helicobacter pylori is now recognised as the cause of gastritis and most cases of peptic ulcer disease (PUD); its long term carriage increases the risk of gastric adenocarcinoma sixfold and it is designated as a class I carcinogen. H pylori has also been implicated as a cause of gastric mucosa associated lymphoid tissue lymphomas. Its relation to non-ulcer dyspepsia remains controversial. Additionally, long term carriage of the organism may be associated with short stature in young girls and, in the general population, as a possible risk factor for the development of vasospastic disorders and possibly skin immunopathology such as urticaria. With the recognition of H pylori as an important human pathogen, it has become one of the growing number of organisms to have its complete genome sequence mapped. Serology is an important method of determining colonisation status and can be used for diagnosis, as a screening procedure, or to follow the efficacy of eradication regimens. Most serological assays are in the ELISA format although some are based on the latex agglutination reaction. These latter are used principally as near patient assays. Most assays detect IgG in serum although some detect serum IgA. More recently developed assays detect IgA in saliva and the production of affinity purified antibodies has led to the development of an antigen detection assay for faecal specimens. Serological reagents have also been used in immunocytochemistry and to speed up the detection of amplified products of the polymerase chain reaction (PCR)-DNA immunoassays.

Endoscopic findings, Helicobacter pylori status, and dyspeptic complaints in vagotomized or medically treated peptic ulcer patients and healthy community controls

BACKGROUND

The recommendation that Helicobacter pylori be eradicated in surgically treated peptic ulcer patients, regardless of complaints and ongoing ulceration, is controversial. To explore possible endoscopic changes associated with vagotomy and long-term acid suppression, the objectives of this study were to compare the endoscopic findings in the upper gastrointestinal mucosa in relation to H. pylori infection and dyspeptic symptoms in peptic ulcer patients treated surgically or medically.

METHODS

Eighty-three randomly selected previously vagotomized peptic ulcer patients, 73 medically treated peptic ulcer patients, and a reference group of 88 healthy community controls underwent an endoscopic investigation. H. pylori infection was determined by culture growth augmented by histology. The endoscopist was blinded for the symptoms and the medical history of all subjects.

RESULTS

H. pylori infection was found in 79% of the vagotomized patients, 75% of the medically treated patients, and 70% of the controls. No malignant lesions were found. Active peptic ulceration was the only endoscopic finding associated with abdominal complaints or H. pylori infection. More than half of subjects with normal endoscopy had H. pylori infection.

CONCLUSIONS

No differences in endoscopic findings between the surgically and medically treated peptic ulcer patients could be found. The findings do not lend any support to H. pylori infection per se as an indication for eradication therapy in previously vagotomized peptic ulcer patients.

Evaluation of three commercial enzyme-linked immunosorbent assay kits for diagnosis of Helicobacter pylori in Chinese patients

Most of the commercial serological assays for H. pylori are developed and validated in western countries. We evaluated the accuracy of three popular commercial ELISA tests for H. pylori in the Chinese population. Eighty dyspeptic patients were recruited and diagnosis of H. pylori infection was based on biopsy urease test, histology and urea breath test. Thirty-six patients (45%) were positive for H. pylori infection by two or more positive reference tests. Anti-H. pylori IgG antibody was detected by three commercial ELISA tests: GAP IgG (Bio-Rad), HM-CAP (Enteric Products) and Pyloriset EIA-G (Orion). The respective sensitivity, specificity, positive and negative predictive values of the three tests were: GAP IgG (50%, 97.4%, 93.8%, 71.7%), HM-CAP (72.7%, 68.4%, 66.7%, 74.3%) and Pyloriset EIA-G (75%, 86.4%, 81.8%, 80.9%). Despite the high accuracy reported in the West, the performance of these commercial serological tests was unsatisfactory when used in Chinese patients.

Validation and value of an enzyme-linked immunosorbent assay for Helicobacter pylori in primary care

BACKGROUND

Helicobacter pylori infection is related to gastric ulcer and carcinoma. In this study we validated the Pyloriset EIA-G New (a quantitative enzyme-linked immunosorbent assay) in a general practice population. The implications of eradication in case of a positive result were assessed.

METHODS

One hundred and fifteen subsequent patients, enrolled in a randomized clinical trial evaluating the optimal strategy for treatment of dyspeptic patients in primary care, were included. Using biopsy as gold standard, we calculated the sensitivity and specificity of the test.

RESULTS

The sensitivity and specificity of the test were 91% (95% confidence interval (CI) = 86% to 97%) and 78% (95% CI = 75% to 82%), respectively. Eradication of H. pylori would be indicated in 8 of 57 positive patients, since these actually had a peptic ulcer. In the other 49 patients eradication therapy would be unnecessary.

CONCLUSION

The Pyloriset EIA-G New is a reliable test in primary care. However, a serologic test-and-treat strategy in all dyspeptic patients cannot be recommended.

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.

Short-term follow-up by serology of patients given antibiotic treatment for Helicobacter pylori infection

Helicobacter pylori serology and in particular enzyme-linked immunosorbent assays for the measurement of immunoglobulin G (IgG) antibody titers form an accurate means of diagnosing H. pylori infection in patients before treatment. H. pylori serology is of limited value in monitoring treatment because of the slow decline in antibody titers. In the present study we aimed to measure the most suitable moment after antibiotic treatment at which serology should be used to monitor treatment. Sixty-four patients who had nonulcer dyspepsia and H. pylori infection and who underwent upper gastrointestinal endoscopy because of persistent dyspeptic symptoms were included in the study. H. pylori cure was confirmed by histology and culture 5 weeks after the completion of the antibiotic treatment. Serological examination was performed before therapy and at 5 weeks, 10 weeks, and 1 year after the completion of antibiotic treatment. Diagnostic performance was assessed by receiver-operating characteristic analysis. The areas under the receiver-operating characteristic curves of the H. pylori antibody titers at 5 weeks, 10 weeks, and 1 year after the completion of treatment were 0.53 (95% confidence interval [CI], 0.36 to 0.69), 0.60 (95% CI, 0.43 to 0.76), and 0.78 (95% CI, 0.63 to 0.93), respectively. The areas under the receiver-operating characteristic curves of the changes in H. pylori IgG antibody titers at 5 weeks, 10 weeks, and 1 year after the completion of treatment in comparison with the pretreatment titers were 0.85 (95% CI, 0.72 to 0.97), 0.96 (95% CI, 0.89 to 1.0), and 1.0 (95% CI, not estimable), respectively. We conclude that serology forms a useful means of monitoring treatment in patients with nonulcer dyspepsia and H. pylori infection as early as 10 weeks and maybe even sooner after the completion of treatment for the infection.

Use of immunoblot assay to define serum antibody patterns associated with Helicobacter pylori infection and with H. pylori-related ulcers

Serology has been used worldwide to detect Helicobacter pylori infection. Using an immunoblot assay with an antigen from strain ATCC 43579, we sought to determine the antibodies which were good markers of colonization and the antibody patterns associated with ulcers or atrophy. Out of 98 dyspeptic patients, 41 were colonized by H. pylori, based on a positive culture or on positive results of both a urease test and direct examination. These 41 patients were seropositive by an enzyme immunoassay, and 12 of them had ulcers and 29 had evidence of atrophy. Fifty-seven of the 98 patients were noncolonized. Twenty-five of the 57 had evidence of gastric atrophy, and 10 were seropositive; 5 of these 10 had ulcers. By Western blot analysis, 12 antibodies were significantly more frequent in sera from colonized patients, and they produced immunoreactive bands at 125, 87, 74, 66, 54, 48, 46, 42, 35, 30, 16 and 14 kDa. The presence of at least one band at 54, 35, or 42 kDa was the best marker of infection (sensitivity, 95%; specificity, 82%). In the group of colonized patients, none of the antibody patterns were correlated to gastric atrophy. Conversely, the presence of a band at 125, 87, or 35 kDa was statistically associated with the presence of an ulcer. The simultaneous presence of bands at 87 and 35 kDa predicted the risk of ulcers with 83% sensitivity and 69% specificity. By using CagA-positive and VacA-positive strains and CagA-negative and VacA-negative isogenic mutants, the antigens corresponding to the bands at 125 and 87 kDa were shown to be CagA and VacA, respectively. On the other hand, the 35-kDa antigen is a novel uncharacterized component of H. pylori. These results may help to optimize the composition of antigenic preparations for serologic detection of H. pylori colonization. Immunoblot assay would be useful for screening patients at high risk of ulcers.

Evaluation and comparison of two immunodiagnostic assays for Helicobacter pylori antibodies with culture results

Several commercially available serological kits have been used as an alternative to endoscopy for the diagnosis of Helicobacter pylori infection. We evaluated the performance of two such kits, Serion H. pylori immunotab kit (Serion, Wurzberg, West Germany) and Pyloragen H. pylori test kit (Hypcor Biomedical Inc., Irvine, CA). Gastric biopsy and serum samples were collected from 345 consecutive dyspeptic patients. The culture and or direct smear of the biopsy was positive for H. pylori in 228 patients (66%), whereas 117 patients (34%) were found to be H. pylori negative. We determined the serological response of the patients using the two kits, both of which are based on the principle of enzyme-linked immunosorbent assay. Comparing the serum immunoglobin G (IgG) and IgA (in a limited number of cases) responses to H. pylori status, the sensitivity, the specificity, positive predictive value, and negative predictive value were calculated. The corresponding data for the different tests were 64%, 79%, 84%, and 56% for Serion IgC, 32%, 94%, 88%, and 52% for Serion IgA, and 88%, 17%, 62%, and 46% for Pyloragen IgG, respectively. We conclude that there is a poor correlation between the presence of H. pylori infection and the antibody response, which could be explained either because of low sensitivities and specificities of the commercial kits used for the measurement of antibodies to H. pylori in the serum or because of poor immunological response in our patients to H. pylori antigens.

Peptic ulcer bleeding in the elderly: relative roles of Helicobacter pylori and non-steroidal anti-inflammatory drugs

BACKGROUND

Most ulcers are caused, one can deduce, by Helicobacter pylori or by use of non-steroidal anti-inflammatory drugs (NSAIDs). Whether both together are worse than one alone is something that is quite unknown.

AIM

To study both factors in order to see wither they interact together positively.

METHOD

A case control study of ulcer bleeding in elderly patients chosen without weeding.

RESULTS

NSAID usage increased risk substantially. So did H pylori infection (but relative risk less than three). Neither seemed to interact. Their actions were discretely intact.

CONCLUSION

H pylori effects ulcer bleeding in an adverse manner but does not make the risk of NSAIDs worse.