Comparison of a stool antigen test and serology for the diagnosis of Helicobacter pylori infection in mass survey

An investigative study on the zoonotic potential of Helicobacter pylori

BACKGROUND

Helicobacter pylori is one of the most common bacterial infections and is widespread globally. It causes a variety of gastrointestinal disorders, though a great proportion of infections are asymptomatic. A total of 143 fresh stool samples were collected from apparently healthy farm and pet animals (43 cattle, 50 buffaloes, 50 sheep, 50 dogs, and 50 cats), in addition to 768 human stool samples. The samples were examined using stool antigen and rapid antibody tests, and further confirmation of glmM "human antigen-positive samples and animal milk samples" was conducted by polymerase chain reaction (PCR).

RESULTS

The prevalence rates of H. pylori infection in animals were 22.2% and 16% in antibody and stool antigen tests, respectively. The detection rates were 28%, 24%, 12%, 10%, and 4.7% in cats, dogs, buffaloes, sheep, and cattle, respectively. On the other hand, the prevalence rate of H. pylori infection in human stool samples was 74.8%, and a statistically significant association was observed between prevalence and several factors, such as sex, age, and locality. PCR was performed to detect the glmM gene of H. pylori, and this gene was found in 21 of 27 human antigen-positive samples and 5 of 13 animal milk samples.

CONCLUSIONS

H. pylori was detected in both human and animal samples. Furthermore, glmM was found in milk and human samples. Our findings suggest that pet and farm animals could transmit H. pylori infection to humans.

Helicobacter pylori Infection, Its Laboratory Diagnosis, and Antimicrobial Resistance: a Perspective of Clinical Relevance

Despite the recent decrease in overall prevalence of Helicobacter pylori infection, morbidity and mortality rates associated with gastric cancer remain high. The antimicrobial resistance developments and treatment failure are fueling the global burden of H. pylori-associated gastric complications. Accurate diagnosis remains the opening move for treatment and eradication of infections caused by microorganisms. Although several reports have been published on diagnostic approaches for H. pylori infection, most lack the data regarding diagnosis from a clinical perspective. Therefore, we provide an intensive, comprehensive, and updated description of the currently available diagnostic methods that can help clinicians, infection diagnosis professionals, and H. pylori researchers working on infection epidemiology to broaden their understanding and to select appropriate diagnostic methods. We also emphasize appropriate diagnostic approaches based on clinical settings (either clinical diagnosis or mass screening), patient factors (either age or other predisposing factors), and clinical factors (either upper gastrointestinal bleeding or partial gastrectomy) and appropriate methods to be considered for evaluating eradication efficacy. Furthermore, to cope with the increasing trend of antimicrobial resistance, a better understanding of its emergence and current diagnostic approaches for resistance detection remain inevitable.

Methods for detection of Helicobacter pylori from stool sample: current options and developments

Accurate detection of Helicobacter pylori infection and determination of antibiotics have significant meaning in clinical practice. The detection methods can be categorized into two types, invasive and non-invasive, but nowadays we use the urease breath test most frequently which is non-invasive. However, many developing countries cannot meet the requirements for having specialized equipment and they lack trained personnel. Also, for the children, it is difficult to make them cooperate for the test. Methods that detect Helicobacter pylori from stool sample can be a promising alternative for detection used in children and mass screening. Stool antigen tests have several advantages such as rapidity, simplicity, and cheapness, though their results may be influenced by the heterogenicity of antigens, the nature of biochemical techniques, and the amount of antigen presented in the stool. PCR-based methods can specifically detect Helicobacter pylori infection and antibiotic resistance by targeting specific gene sequence, but they also are limited by the requirements of facilities and experts, the existence of inhibitory substance, and interference from the dead bacteria. Some novel methods also deserve our attention. Here we summarized the results of researches about methods using stool sample and we hope our work can help clinicians choose the appropriate test in clinical practice.

Evaluation of antibody immunochromatography testing for diagnosis of current Helicobacter pylori infection

Background

Helicobacter pylori infection represents a major gastrointestinal complaint associated with gastritis, gastric ulcer and stomach tumors. It is present in 90 % of developing countries population. H. pylori diagnosis in these countries, where resources are limited, is accomplished with simple non-invasive tests such as stool antigen and serum antibody tests. The aim of this study was to evaluate the serum antibody test in the diagnosis of current H. pylori infection.

Subject and methods

A total of 117 patients were included in this prospective diagnosis accuracy testing study, who clinically presented with dyspepsia, heartburn, abdominal pain, diarrhea, or halitosis. A stool sample was collected from each patient and tested for H. pylori antigen using immunochromatographic method.Blood sample was also collected, half of which was EDTA-sampled and analyzed for complete blood count, while the remaining half was left to clot, the separated serum was tested for antibodies against H. pylori with immunochromatographic cassette.

Results

About 35 % of sixty six patients who were positive for stool antigen test gave a negative for serum antibodies test. Meanwhile, the non-consistent results within 51 negative stool antigen test patients was exhibited by 47 % of them. The discrepancies were not affected by age or disease duration. The calculated sensitivity, specificity, positive predictive value and negative predictive values were 50 %, 65 %, 65 % and 50 % respectively.

Conclusion

The serum antibody test is not reliable in the diagnosis of current H. pylori infection. In developing countries, with limited facilities and primary care units, stool antigen test diagnosis is useful for diagnosis.

Accurate Detection of Helicobacter pylori Antigen in Human Stool Specimens by Two Novel Immunoassays

Stool antigen tests are recommended for the diagnosis of Helicobacter pylori infection. Here, we compared two novel assays, i.e., one enzyme immunoassay (EIA) and one immunochromatography assay (ICA), with a chemiluminescence immunoassay (CLIA) that had previously been compared with rapid urease test, histology, and urea breath test. Two hundred sixty-six frozen stool samples with defined CLIA results (42 positives, 219 negatives, and 5 samples with borderline results) collected between January and May 2018 were thawed and immediately tested by EIA, ICA, and CLIA. In 248 samples with repeatedly positive/negative CLIA results, EIA and ICA were positive for 40 and 37 of 41 CLIA-positive samples and yielded negative results for 206 and 201 of 207 CLIA-negative samples, respectively. There was a high positive percent agreement (EIA, 97.6%; 95% confidence interval (95% CI), 86.3-100%; ICA, 90.2%; 95% CI, 76.9-96.7%), as well as a negative percent agreement between the assays (EIA, 99.5%; 95% CI, 97.0-100%; ICA, 97.1%; 95% CI, 93.7-98.8%). This was further supported by kappa values indicating very good agreement (CLIA vs. EIA, 0.971; CLIA vs. ICA, 0.857). In conclusion, both EIA and ICA comprise valuable assays for the detection of H. pylori antigen in stool samples.

Characteristics of Helicobacter pylori-seropositive subjects according to the stool antigen test findings: a prospective study

BACKGROUND/AIMS

In countries with a higher risk of gastric atrophic gastritis, noninvasive tests are helpful for a more reliable diagnosis of Helicobacter pylori infection. The aim of this study was to evaluate the characteristics of seropositive subjects according to their stool H. pylori antigen test, serum pepsinogen (PG) assay, and endoscopic findings.

METHODS

Consecutive subjects who visited Konkuk University Medical Center for upper gastrointestinal endoscopy for a regular check-up were included in a prospective setting if the serum anti-H. pylori immunoglobulin G assay was positive. A H. pylori antigen stool test was measured using a stool H. pylori antigen enzyme-linked immunosorbent assay kit on the same day as a serum PG assay and endoscopy.

RESULTS

Of 318 seropositive subjects, 256 (80.5%) showed positive stool test findings. Subjects with a negative stool test result showed lower serum PG I (p < 0.001) and PG II (p < 0.001) levels and higher PG I/II ratio (p < 0.001) than those with a positive stool test. Chronic atrophic gastritis was more common in the positive stool test group than the negative stool test group on endoscopic finding (p = 0.009). A higher serum PG I level (p = 0.001) and a lower serum PG I/II ratio (p = 0.001) were independent risk factors for the presence of H. pylori antigen in stool.

CONCLUSION

A high serum PG level denotes an ongoing current H. pylori infection with positive stool H. pylori antigen test findings. Seropositive subjects with increased gastric secreting ability tend to have H. pylori in their fecal material as reflected by a positive stool H. pylori antigen test finding.

Feco-prevalence and risk factors of Helicobacter pylori infection among symptomatic patients at Dessie Referral Hospital, Ethiopia

BACKGROUND

Helicobacter pylori (H. pylori) infection is the most common chronic bacterial infection in the world. It can result in various upper gastroduodenal diseases. The prevalence varies among countries, population groups within the same country and testing methods. The aim of the study was to determine feco-prevalence and risk factors of H.pylori infection among symptomatic patients in Amhara region, Northeast Ethiopia.

METHODS

A cross sectional study was conducted in a total of 342 new consecutive outpatients with upper abdominal complaints at Dessie Referral Hospital from May to July, 2016. A structured questionnaire was used to collect the socio-demographic, lifestyle and environmental data. Stool samples were used to detect H. pylori specific antigen. Blood samples were assessed for anti-H. pylori IgG and ABO blood types. SPSS version 20.0 statistical software package was used for data analysis. Chi-square test and logistic regression were used in the analysis and P-value ≤0.05 was considered as statistically significant.

RESULTS

H. pylori stool antigen and serum anti-H.pylori IgG detection rate was 30.4 and 60.5% respectively with kappa measure of agreement of 0.271. Antigen detection was significantly associated with family size (> 3) [AOR = 1.83, 95% CI: 1.10-3.05, p = 0.02], more persons (> 3) sharing the same bed room in the household [AOR = 2.91, 95% CI: 1.39-6.11, p = 0.005], alcohol consumption (> once a week) [AOR = 2.70, 95% CI: 1.49-4.89, p = 0.001] and individuals' blood type: group O [AOR = 8.93, 95%CI: 1.79-44.48, p = 0.008] and group A [AOR = 5.53, 95%CI: 1.08-28.36, p = 0.040]. Gender, age, marital status, occupation, educational level, residence, smoking as well as coffee, tea, fruits and vegetables consumption were not statistically associated with H. pylori antigen detection (p > 0.05).

CONCLUSION

The overall H. pylori stool antigen and anti-H. pylori IgG detection rate was 30.4 and 60.5%, respectively. The test agreement was not strongly convincing and needs further evaluation. Alcohol consumption, overcrowding and ABO blood group were significantly associated with H. pylori antigen detection.

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.

A screening program to test and treat for Helicobacter pylori infection: Cost-utility analysis by age, sex and ethnicity

BACKGROUND

The World Health Organization recommends all countries consider screening for H. pylori to prevent gastric cancer. We therefore aimed to estimate the cost-effectiveness of a H. pylori serology-based screening program in New Zealand, a country that includes population groups with relatively high gastric cancer rates.

METHODS

A Markov model was developed using life-tables and morbidity data from a national burden of disease study. The modelled screening program reduced the incidence of non-cardia gastric cancer attributable to H. pylori, if infection was identified by serology screening, and for the population expected to be reached by the screening program. A health system perspective was taken and detailed individual-level costing data was used.

RESULTS

For adults aged 25-69 years old, nation-wide screening for H. pylori was found to have an incremental cost of US$196 million (95% uncertainty interval [95% UI]: $182-$211 million) with health gains of 14,200 QALYs (95% UI: 5,100-26,300). Cost per QALY gained was US$16,500 ($7,600-$38,400) in the total population and 17% (6%-29%) of future gastric cancer cases could be averted with lifetime follow-up. A targeted screening program for Māori only (indigenous population), was more cost-effective at US$8,000 ($3,800-$18,500) per QALY.

CONCLUSIONS

This modeling study found that H. pylori screening was likely to be cost-effective in this high-income country, particularly for the indigenous population. While further research is needed to help clarify the precise benefits, costs and adverse effects of such screening programs, there seems a reasonable case for policy-makers to give pilot programs consideration, particularly for any population groups with relatively elevated rates of gastric cancer.

Diagnosis of Helicobacter pylori infection: Current options and developments

Accurate diagnosis of Helicobacter pylori (H. pylori) infection is a crucial part in the effective management of many gastroduodenal diseases. Several invasive and non-invasive diagnostic tests are available for the detection of H. pylori and each test has its usefulness and limitations in different clinical situations. Although none can be considered as a single gold standard in clinical practice, several techniques have been developed to give the more reliable results. Invasive tests are performed via endoscopic biopsy specimens and these tests include histology, culture, rapid urease test as well as molecular methods. Developments of endoscopic equipment also contribute to the real-time diagnosis of H. pylori during endoscopy. Urea breathing test and stool antigen test are most widely used non-invasive tests, whereas serology is useful in screening and epidemiological studies. Molecular methods have been used in variable specimens other than gastric mucosa. More than detection of H. pylori infection, several tests are introduced into the evaluation of virulence factors and antibiotic sensitivity of H. pylori, as well as screening precancerous lesions and gastric cancer. The aim of this article is to review the current options and novel developments of diagnostic tests and their applications in different clinical conditions or for specific purposes.

Diagnosis of Helicobacter pylori infection: Current options and developments

Accurate diagnosis of Helicobacter pylori (H. pylori) infection is a crucial part in the effective management of many gastroduodenal diseases. Several invasive and non-invasive diagnostic tests are available for the detection of H. pylori and each test has its usefulness and limitations in different clinical situations. Although none can be considered as a single gold standard in clinical practice, several techniques have been developed to give the more reliable results. Invasive tests are performed via endoscopic biopsy specimens and these tests include histology, culture, rapid urease test as well as molecular methods. Developments of endoscopic equipment also contribute to the real-time diagnosis of H. pylori during endoscopy. Urea breathing test and stool antigen test are most widely used non-invasive tests, whereas serology is useful in screening and epidemiological studies. Molecular methods have been used in variable specimens other than gastric mucosa. More than detection of H. pylori infection, several tests are introduced into the evaluation of virulence factors and antibiotic sensitivity of H. pylori, as well as screening precancerous lesions and gastric cancer. The aim of this article is to review the current options and novel developments of diagnostic tests and their applications in different clinical conditions or for specific purposes.

Decrease of serum level of gastrin in healthy Japanese adults by the change of Helicobacter pylori infection

BACKGROUND AND AIM

In Japan, the prevalence of Helicobacter pylori infection is decreasing and the number of patients who receive eradication therapy is increasing. Although the serum level of gastrin is affected by H. pylori infection, the normal level has been unchanged for more than 20 years. The aim of this study was to study whether the present normal range for the serum gastrin level is appropriate for Japanese at present or in the near future.

METHODS

We studied 810 adults (40-80 years old) who participated in a health survey in 2012. We measured H. pylori stool antigen, titer of serum antibody to H. pylori, and serum level of gastrin. The patient's H. pylori status was defined as positive or negative when the results of both stool antigen and serology were concordant. Subjects who were taking proton-pump inhibitor and had a previous history of gastric surgery were excluded.

RESULTS

Mean serum level of gastrin was 66.2±49.6 pg/mL in 281 H. pylori-negative subjects and 69.7±42.2 pg/mL in 115 patients who had H. pylori eradicated at least 2 years ago. The level of gastrin was 134.4±145.6 pg/mL in 224 patients with H. pylori infection and the level was significantly higher when compared with those in uninfected subjects and eradicated patients (P<0.01).

CONCLUSIONS

Because the situation of H. pylori infection has changed remarkably in Japan, a new appropriate normal range of gastrin should be established using current Japanese populations.

Stool antigen tests for the management of Helicobacter pylori infection

Stool antigen tests (SATs) are noninvasive diagnostic modules for Helicobacter pylori (H. pylori) infection. Two types of SATs exist for the diagnosis of H. pylori infection, one based on enzyme immunoassay (EIA) and another on immunochromatography (ICA). SATs do not require expensive chemical agents or specified equipment; hence, they are less expensive compared with the urea breath test. Both European and Japanese guidelines have shown that EIA-based SATs using monoclonal antibodies are useful for primary diagnosis as well as for the assessment of eradication therapy. ICA-based tests do not require particular equipment and are therefore useful in developing countries. SATs are also useful for the diagnosis of H. pylori infection in children and post gastric surgery patients. SATs performed via EIA can assess H. pylori infection in a large number of subjects, almost as well as serology. Thus, SATs would be useful or detecting current infection in such a survey to identify and eradicate H. pylori infection. The accuracy of SATs is lower when the stool samples are unformed or watery, because H. pylori-specific antigens in the stool samples are diluted. Temperature and the interval between stool sample collection and measurement also affect the results of SATs. The choice of test kit depends on the sensitivity and specificity in each region and the circumstances of each patient.

Immunodot blot assay to detect Helicobacter pylori using monoclonal antibodies against the 26 kDa protein

Development of a specific immunoassay to detect Helicobacter pylori infection in stool samples requires monoclonal antibody against the specific antigen. The aims of this study were to establish monoclonal antibodies against the 26 kDa protein of H. pylori and develop an immunodot blot for their application to recognize H. pylori infection using stool samples. Mice were immunized intraperitoneally with homogenized gel containing the 26 kDa band of cell surface proteins of H. pylori in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The monoclonal antibodies were produced using the hybridoma technique. Reactivity of monoclonal antibodies was tested with the purified 26 kDa antigen and cell surface proteins from cultured H. pylori by ELISA. Furthermore reactivity of monoclonal antibodies was tested on negative and positive stool samples for H. pylori and suspensions of several major bacteria in stool by immunodot blot assay. Five stable hybridoma monoclones were obtained. The concordant reactivity of the monoclonal antibodies with H. pylori present in the stool samples, which had been tested previously using an ACON ELISA kit for H. pylori stool antigen testing, and unreactivity with several different major fecal bacteria in immunodot blotting indicates high specificity of the immunodot blot based on the reaction of produced monoclonal antibodies with the H. pylori antigen in stools. The findings indicate that the novel immunodot blot developed based on new monoclonal antibodies for stool antigens would be useful as a noninvasive method of diagnosing H. pylori infection.

Performance of a one-step fecal sample-based test for diagnosis of Helicobacter pylori infection in primary care and mass screening settings

BACKGROUND/PURPOSE

An alternative screening test is needed to efficiently eradicate Helicobacter pylori from a population with prevalent upper gastrointestinal lesions. We evaluated the performance of a new one-step fecal test for H. pylori for diagnosis of H. pylori infection in Taiwan.

METHODS

We developed a fecal test to detect H. pylori based on the immunochronomatographic assay and a mixture of monoclonal antibodies. We first recruited symptomatic patients from the primary care setting to evaluate fecal test performance using a reference standard consisting of (13)C urea breath test, rapid urease test, and histology. We also compared the performance of the fecal test with that of others. Next, we recruited asymptomatic participants from the mass screening setting to evaluate population attendance for the fecal test and compared its performance with that of (13)C urea breath test.

RESULTS

In the primary care setting, 117 patients were recruited; H. pylori infection was confirmed in 58 (49.6%). Fecal test sensitivity, specificity, positive and negative predictive values, and accuracy were 88.0% [95% confidence interval (CI): 79.6-96.4%], 100%, 100%, 89.4% (95% CI, 82.0-96.8%), and 94% (95% CI, 89.7-98.3%), respectively. Fecal test specificity and positive predictive value were significantly higher than those of the serological test, whereas the sensitivity and negative predictive value were lower than those of the (13)C urea breath test (p < 0.05). In the mass screening setting, 2720 of 3520 invited individuals participated (77.3%; 95% CI, 76-78.7%); 649 (23.9%) showed positive results. Concordance rate and kappa statistic between the fecal test and (13)C urea breath test were 91.7% (563/614; 95% CI, 89.9-94.1%) and 0.78 (95% CI, 0.73-0.84), respectively.

CONCLUSION

Given the acceptable sensitivity, excellent specificity, and high participation rate to screening, the one-step H. pylori stool antigen test is feasible for wide application in the community.

Characterization and usefulness of stool antigen tests using a monoclonal antibody to Helicobacter pylori catalase

BACKGROUND AND AIM

Two types of stool antigen tests have been used in the management of Helicobacter pylori infection. Testmate Pylori Antigen enzyme immunoassay (TPAg EIA) is a direct sandwich enzyme immunoassay (EIA) while Testmate Rapid Pylori Antigen (Rapid TPAg) is performed using immunochromatography. The aim of this study was to study the characterization and usefulness of these tests.

METHODS

Accuracy of both tests was studied using 111 fecal samples obtained from H. pylori-positive or -negative patients. Cross-reactivity was examined with four other Helicobacter spp. and five fecal bacteria in humans. To estimate the sensitivity of both kits, we tested H. pylori clinical strains. We also examined the diagnostic performances of both tests after the storage for 12 months.

RESULTS

The accuracy of both Testmate kits was 100% in fecal samples from 111 patients. No cross-reactivity was observed in both Testmate kits in five fecal bacteria and four other Helicobacter spp. TPAg EIA and Rapid TPAg showed positive results in 1342 of 1344, and 483 of 485 clinical strains, respectively. Diagnostic performances was maintained for 12 months when TPAg EIA was stored at 4°C and Rapid TPAg at 30°C.

CONCLUSIONS

We examined the details of high accuracy of TPAg EIA and Rapid TPAg. The diagnostic performance of both kits was maintained after storage for up to 1 year. The two types of tests would be useful in the management of H. pylori infection.

Upper gastrointestinal bleedings in patients with hereditary coagulation disorders in Northwest of Iran: prevalence of Helicobacter pylori infection

OBJECTIVE

Upper gastrointestinal (UGI) bleeding is one of the most life-threatening complications, in up to 25% of persons with hemophilia (PWH). Recurrent bleeding is common and can be caused by the Helicobacter pylori infection. Our aim was to evaluate the role of H. pylori infection in UGI bleeding in PWH.

MATERIAL AND METHODS

Ninety patients with hereditary bleeding disorders, 30 patients with (group A), and 60 patients without (group B) a history of UGI bleeding episodes were included. The prevalence of H. pylori infection was investigated by stool antigen test, and serum serologic tests including immunoglobulin G and anti-CagA.

RESULTS

Among 90 patients (81 men, nine women, mean age 31.30 ± 10.72 years), 66 patients with hemophilia A, 10 patients with hemophilia B, six patients with Von Willebrand disease, five patients with platelet function disorders, and three patients with other factor deficiencies were evaluated. About 46.7% of patients in group A, and 23.3% of patients in group B were anti-CagA-positive (P=0.02), whereas 76.7% of patients in group A and 51.7% of patients in group B had H. pylori immunoglobulin G antibodies (P=0.02). H. pylori antigen in stool was positive in 76.7% in group A and 55% in group B (P=0.03). No statistically significant difference was found between type and severity of diseases and risk of UGI.

CONCLUSION

H. pylori infection should be considered as an important cause of UGI bleeding in PWH. We would recommend stool antigen test as a new and noninvasive screening test for diagnosis of H. pylori infection in all patients with hereditary hemorrhagic disorders.

The prevalence and incidence of Helicobacter pylori-associated peptic ulcer disease and upper gastrointestinal bleeding throughout the world

Due to heightened awareness regarding testing for and eradication of infection, the prevalence and incidence of H pylori infection (and by extension the prevalence and incidence of peptic ulcer disease) appear to have declined in recent years. However, antimicrobial resistance is mounting and traditional clarithromycin- or metronidazole-containing triple therapies may no longer be highly effective at eradicating the infection. Combined bismuth- and metronidazole-containing quadruple therapy or sequential 4-drug therapy may be better choices for first-line treatment against this unique pathogen that is ideally suited to survive in the human stomach.

Performance of the immunochemical fecal occult blood test in predicting lesions in the lower gastrointestinal tract

BACKGROUND

Previous studies have suggested that the immunochemical fecal occult blood test has superior specificity for detecting bleeding in the lower gastrointestinal tract even if bleeding occurs in the upper tract. We conducted a large population-based study involving asymptomatic adults in Taiwan, a population with prevalent upper gastrointestinal lesions, to confirm this claim.

METHODS

We conducted a prospective cohort study involving asymptomatic people aged 18 years or more in Taiwan recruited to undergo an immunochemical fecal occult blood test, colonoscopy and esophagogastroduodenoscopy between August 2007 and July 2009. We compared the prevalence of lesions in the lower and upper gastrointestinal tracts between patients with positive and negative fecal test results. We also identified risk factors associated with a false-positive fecal test result.

RESULTS

Of the 2796 participants, 397 (14.2%) had a positive fecal test result. The sensitivity of the test for predicting lesions in the lower gastrointestinal tract was 24.3%, the specificity 89.0%, the positive predictive value 41.3%, the negative predictive value 78.7%, the positive likelihood ratio 2.22, the negative likelihood ratio 0.85 and the accuracy 73.4%. The prevalence of lesions in the lower gastrointestinal tract was higher among those with a positive fecal test result than among those with a negative result (41.3% v. 21.3%, p < 0.001). The prevalence of lesions in the upper gastrointestinal tract did not differ significantly between the two groups (20.7% v. 17.5%, p = 0.12). Almost all of the participants found to have colon cancer (27/28, 96.4%) had a positive fecal test result; in contrast, none of the three found to have esophageal or gastric cancer had a positive fecal test result (p < 0.001). Among those with a negative finding on colonoscopy, the risk factors associated with a false-positive fecal test result were use of antiplatelet drugs (adjusted odds ratio [OR] 2.46, 95% confidence interval [CI] 1.21-4.98) and a low hemoglobin concentration (adjusted OR 2.65, 95% CI 1.62-4.33).

INTERPRETATION

The immunochemical fecal occult blood test was specific for predicting lesions in the lower gastrointestinal tract. However, the test did not adequately predict lesions in the upper gastrointestinal tract.

Clinical study of the relationship between Helicobacter pylori and chronic urticaria and prurigo chronica multiformis: effectiveness of eradication therapy for Helicobacter pylori

Eighty two patients with chronic urticaria and 17 patients with prurigo chronica multiformis were referred to our department from October 2004 to February 2007 and were tested for Helicobacter pylori antigen using the polyclonal H. pylori stool antigen test (enzyme-linked immunosorbent assay method). H. pylori antigen was detected in 25 (30.5%) of the 82 patients with chronic urticaria and in 10 (58.8%) of the 17 patients with prurigo chronica multiformis. Those findings were not significantly higher than the positive rate for H. pylori stool antigen in healthy age-matched controls. In patients positive for H. pylori antigen, seven of the 25 with chronic urticaria had complications of gastritis (six patients) or gastric ulcers (one patient). Three of the 10 patients with prurigo chronica multiformis had complications of gastritis (two patients) or gastric ulcers (one patient). We examined the therapeutic efficacy of antibacterial treatment for the 17 patients with chronic urticaria and the eight patients with prurigo chronica multiformis who were positive for H. pylori antigen and accepted the treatment based on informed consent. We evaluated the effectiveness of treatment by scoring the skin conditions and by using the Skindex-16, a measure of quality of life. The eradication therapy for H. pylori was more effective for treating prurigo chronica multiformis and the skin symptoms started to improve within 3-14 days after the therapy. However, that therapy was not always effective for treating chronic urticaria. We suggest that H. pylori may be an important pathogenetic factor, especially for prurigo chronica multiformis, and that eradication therapy should be considered to treat intractable cases.

Epidemiology of Helicobacter pylori infection and public health implications

This article summarizes the published literature concerning the epidemiology and public health implications of Helicobacter pylori infection published from April 2009 through March 2010. Prevalence of infection varied between 7 and 87% and was lower in European studies. All retrieved studies examining transmission of infection concluded that spread is from person-to-person. One study collecting stool and vomitus samples from patients with acute gastroenteritis detected H. pylori DNA in 88% of vomitus and 74% of stool samples. Proposed risk factors for infection included male gender, increasing age, shorter height, tobacco use, lower socioeconomic status, obesity, and lower educational status of the parents in studies conducted among children. Decision analysis models suggest preventing acquisition of H. pylori, via vaccination in childhood, could be cost-effective and may reduce incidence of gastric cancer by over 40%. As yet, no country has adopted public health measures to treat infected individuals or prevent infection in populations at risk.

Validation of a rapid stool antigen test for diagnosis of Helicobacter pylori infection

The aim of this study was to validate the rapid lateral flow Helicobacter pylori stool antigen test (One step H. pylori antigen test, ACON laboratories, San Diego, USA; Prime diagnostics, São Paulo), using 13C-Urea Breath Test as the gold standard for H. pylori infection diagnosis. A total of 98 consecutive patients, asymptomatic or dyspeptic, entered the study. Sixty-nine were women, with a mean age of 45.76 ± 14.59 years (14 to 79 years). In the H. pylori-positive group, the rapid stool antigen test detected H. pylori antigen in 44 of the 50 positive patients (sensitivity 88%; 95% CI: 75.7-95.5%), and six false-negative; and in the H. pylori-negative group 42 presented negative results (specificity 87.5%; 95% CI: 74.7-95.3%), and six false-positive, showing a substantial agreement (Kappa Index = 0.75; p < 0.0001; 95% CI: 0.6-0.9). Forty four of fifty patients that had positive stool antigen were H. pylori-positive, the PPV of the stool antigen test was 88% (95% CI: 75.7-95.5%), and 42 patients with negative stool antigen test were H. pylori-negative, the NPV of the stool antigen test was 87.5% (95% CI: 74.7-95.3%). We conclude that the lateral flow stool antigen test can be used as an alternative to breath test for H. pylori infection diagnosis especially in developing countries.

Helicobacter pylori: diagnosis and treatment

PURPOSE OF REVIEW

Multiple diagnostic methods and treatment strategies have been developed to detect and treat the Helicobacter pylori infection. Many of them have stood the test of time; others lost their value with the introduction of new test and treatment modalities. This review focuses on the current diagnostic methods and their clinical implications, as well as on established and novel treatment strategies.

RECENT FINDINGS

The increasing antimicrobial resistance has resulted in a decline of the success rate of recommended eradication regimens. The current guidelines recommend as first-line treatment clarithromycin, amoxicillin or metronidazole, and proton pump inhibitor twice daily, but recent studies have demonstrated an increasing eradication failure with these regimens. Several treatment modifications have been adopted regarding duration and combination of substances.

SUMMARY

The currently recommended first-line treatments are effective and well tolerated. In areas with high antimicrobial resistance rates, new antibiotic combinations and modifications in the sequence of drug administration are proposed as alternative treatment options to standard triple therapy. Future treatment strategies have to focus on regional antimicrobial resistance adopted treatment selection and the development of new antibiotics.

Epidemiology of Helicobacter pylori infection in asymptomatic children: a prospective population-based study from the Czech Republic. Application of a monoclonal-based antigen-in-stool enzyme immunoassay

BACKGROUND

Acquisition of Helicobacter pylori occurs mainly in childhood and is significantly influenced by geographical variations. The aim of this study is to evaluate the prevalence of H. pylori infection in a population-based sample of asymptomatic children in the Czech Republic. Furthermore, this study aims to identify potential risk factors associated with this infection.

MATERIALS AND METHODS

A prospective, cross-sectional, population-based study was undertaken in 1545 asymptomatic Czech children (aged 0-15 years; male 49.3%). Active H. pylori infection was diagnosed by monoclonal antibody-based antigen-in-stool enzyme immunoassay. Socio-demographic details of each subject were analyzed using a self-administered standardized questionnaire. Multiple regression analysis was performed.

RESULTS

Overall, 7.1% of asymptomatic children were diagnosed with H. pylori infection. Of the infected children, 5.8% lived in the general population. A positive association was found with increasing age, although not with gender. Independent risk factors associated with H. pylori infection in our pediatric population were: the number of children in a household (odds ratio [OR] 4.26; confidence interval [CI] 1.91-9.80); lack of formal education of fathers (OR 0.23; CI 0.18-0.64) and institutionalized children (OR 6.33; CI 2.25-26.50).

CONCLUSIONS

This study of a large cohort of children demonstrated that, independent of gender, H. pylori infection in the Czech Republic is among the lowest reported in Europe. Socioeconomically disadvantaged children, unfortunately, are still at risk of harboring this potentially preventable infection in this low-prevalence region.