Influence of proton pump inhibitor treatment on Helicobacter pylori stool antigen test

Retrospective analysis of discordant results between histology and other clinical diagnostic tests on helicobacter pylori infection

BACKGROUND

A reliable test is essential for diagnosing Helicobacter pylori (H. pylori) infection, and crucial for managing H. pylori-related diseases. Serving as an excellent method for detecting H. pylori infection, histologic examination is a test that clinicians heavily rely on, especially when complemented with immunohistochemistry (IHC). Additionally, other diagnostic tests for H. pylori, such as the rapid urease test (CLO test) and stool antigen test (SA), are also highly sensitive and specific. Typically, the results of histology and other tests align with each other. However, on rare occasions, discrepancy between histopathology and other H. pylori diagnostic tests occurs.

AIM

To investigate the discordance between histology and other H. pylori tests, the underlying causes, and the impact on clinical management.

METHODS

Pathology reports of gastric biopsies were retrieved spanning August 2013 and July 2018. Reports were included in the study only if there were other H. pylori tests within seven days of the biopsy. These additional tests include CLO test, SA, and H. pylori culture. Concordance between histopathology and other tests was determined based on the consistency of results. In instances where histology results were negative while other tests were positive, the slides were retrieved for re-assessment, and the clinical chart was reviewed.

RESULTS

Of 1396 pathology reports were identified, each accompanied by one additional H. pylori test. The concordance rates in detecting H. pylori infection between biopsy and other tests did not exhibit significant differences based on the number of biopsy fragments. 117 discrepant cases were identified. Only 20 cases (9 with CLO test and 11 with SA) had negative biopsy but positive results in other tests. Four cases initially stained with Warthin-Starry turned out to be positive for H. pylori with subsequent IHC staining. Among the remaining 16 true discrepant cases, 10 patients were on proton pump inhibitors before the biopsy and/or other tests. Most patients underwent treatment, except for two who were untreated, and two patients who were lost to follow-up.

CONCLUSION

There are rare discrepant cases with negative biopsy but positive in SA or CLO test. Various factors may contribute to this inconsistency. Most patients in such cases had undergone treatment.

Evaluation of the effects of a proton pump inhibitor on Helicobacter pylori stool antigen testing

BACKGROUND

Some patients find it difficult to discontinue proton pump inhibitors (PPIs). Unlike the ¹³ C-urea breath test (UBT), the stool antigen test (SAT), particularly when domestically produced kits are used, may be less likely to yield false-negative results.

METHODS

This prospective study included a convenience series of 35 healthy Japanese subjects. Based on a statistical calculation, acceptable numbers of subjects were considered at least 21 and 11 with and without Helicobacter pylori (H. pylori) infection, respectively. The H. pylori infection was determined using the UBT or rapid urease test. SATs were performed with three novel domestically produced kits (the rapid immunochromatography tests Quick Navi™-H. pylori [Navi™] and Quick Chaser® H. pylori [Chaser®], and the bioluminescent enzyme immunoassay test BLEIA® 'EIKEN' H. pylori Antigen [BLEIA®]) before and after oral PPI administration (30 mg lansoprazole once daily for 14 days). For each kit, the sensitivities and specificities were calculated and compared before and after PPI administration. Furthermore, the cutoff index (COI) values of BLEIA® before and after PPI administration were compared in H. pylori-infected subjects.

RESULTS

H. pylori infection was detected in 68.6% (24/35) of the included subjects. The sensitivities and specificities before versus after PPI administration were as follows: 79.2% (19/24) and 100.0% (11/11) versus 75.0% (18/24) and 100.0% (11/11) for Navi™, respectively (p = 1); 87.5% (21/24) and 100.0% (11/11) versus 75.0% (18/24) and 100.0% (11/11) for Chaser®, respectively (p = .371); 100.0% (24/24) and 100.0% (11/11) versus 95.8% (23/24) and 100.0% (11/11) for BLEIA®, respectively (p = 1). The median COI values of BLEIA® before and after PPI administration were 1389.0 and 3207.25, respectively (p = .0839).

CONCLUSIONS

In stool specimens, H. pylori antigenicity is maintained even during PPI use. SAT using a bioluminescent enzyme immunoassay is particularly recommended because of its extremely high sensitivity.

Risk of Helicobacter pylori transmission by faecal microbiota transplantation via oral capsules

OBJECTIVES

The aim was to determine if Helicobacter pylori is transmitted from donors to recipients by faecal microbiota transplantation (FMT) via oral capsules.

METHODS

In a cohort of faeces donors not primarily screened for H. pylori, consecutive stool samples were retrospectively analysed by the H. pylori stool antigen test (SAT). Subsequently, we analysed recipient stool samples collected before and after receiving faeces donated by H. pylori SAT-positive donors, and we recorded recipient use of antibiotics and proton pump inhibitors. All stool samples were frozen upon collection and stored at -80°C until use.

RESULTS

Thirteen out of 40 faeces donors (33%; 95% CI, 20-48%) were H. pylori SAT-positive. Among those positive, five donors donated faeces for 28 capsule-based FMTs performed in 26 recipients with stool samples collected before and after FMT. At a median of 59 days (range, 7-84 days) after FMT, no recipients (0%; 95% CI, 0-11%) were H. pylori SAT-positive.

DISCUSSION

We found no occurrence of H. pylori transmission from healthy, asymptomatic donors to recipients by oral capsule-based FMT, although with a wide CI.

Advanced Sensing Strategies Based on Different Types of Biomarkers toward Early Diagnosis of H. pylori

Helicobacter pylori (H. pylori) is a bacterium that can colonize human gastric epithelial cells and cause H. pylori infection, closely related to many gastric diseases. Compared with conventional H. pylori detection methods, emerging diagnostic approaches (such as biosensors) have become potentially more effective alternatives due to their high sensitivity, good selectivity and noninvasiveness. This review begins with a brief overview of H. pylori infection, the processes that lead to diseases, and current diagnostic methods. Subsequently, advanced biosensors in different target-based for diagnosing H. pylori infection are focused, including the detection of H. pylori-related nucleic acid, H. pylori-related protein (such as the cytotoxin, urease), and intact H. pylori. In addition, prospects for the development of H. pylori detection methods are also discussed in the end.

Management of Helicobacter pylori infection

Helicobacter pylori infection exhibits a wide disease spectrum ranging from asymptomatic gastritis, peptic ulcer disease, to gastric cancer. H. pylori can induce dysbiosis of gastric microbiota in the pathway of carcinogenesis and successful eradication can restore gastric homeostasis. Diagnostic testing and treatment for H. pylori infection is recommended in patients with active or past history of peptic ulcer, chronic dyspepsia, chronic non-steroidal anti-inflammatory drugs (NSAID) or aspirin use, precancerous gastric lesions, gastric cancer, mucosa-associated lymphoid tissue (MALT) lymphoma, family history of gastric cancer, family history of peptic ulcers, household family member having active H. pylori infection, iron deficiency anemia, idiopathic thrombocytopenic purpura, or vitamin B12 deficiency. Recommended first-line regimens for H. pylori eradication are classified according to clarithromycin resistance. In areas of high clarithromycin resistance (≥15%), we recommend 14-day concomitant therapy or 14-day bismuth quadruple therapy (BQT) as first-line regimen. In areas of low clarithromycin resistance (<15%), we recommend 14-day triple therapy or 14-day BQT as first-line treatment. Second-line regimens are 14-day levofloxacin triple therapy or 14-day BQT if BQT is not previously used. For patients with multiple treatment failure, antimicrobial susceptibility testing (AST) should be performed. If AST is not available, we recommend using antibiotics not previously used or for which resistance is unlikely, such as amoxicillin, tetracycline, bismuth, or furazolidone. High-dose potent proton pump inhibitor or vonoprazan is recommended to achieve adequate acid suppression. Probiotics can be used as an adjuvant treatment to reduce the side effects of antibiotics and enhance eradication rate.

Evaluation of a New Monoclonal Chemiluminescent Immunoassay Stool Antigen Test for the Diagnosis of Helicobacter pylori Infection: A Spanish Multicentre Study

The stool antigen test (SAT) represents an attractive alternative for detection of Helicobacter pylori. The aim of this study was to assess the accuracy of a new SAT, the automated LIAISON® Meridian H. pylori SA based on monoclonal antibodies, compared to the defined gold standard 13C-urea breath test (UBT). This prospective multicentre study (nine Spanish centres) enrolled patients ≥18 years of age with clinical indication to perform UBT for the initial diagnosis and for confirmation of bacterial eradication. Two UBT methods were used: mass spectrometry (MS) including citric acid (CA) or infrared spectrophotometry (IRS) without CA. Overall, 307 patients (145 naïve, 162 with confirmation of eradication) were analysed. Using recommended cut-off values (negative SAT < 0.90, positive ≥ 1.10) the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 67%, 97%, 86%, 92% and 91%, respectively, obtaining an area under the receiver operating characteristic (ROC) curve (AUC) of 0.85. Twenty-eight patients, including seven false positives and 21 false negatives, presented a discordant result between SAT and UBT. Among the 21 false negatives, four of six tested with MS and 11 of 15 tested with IRS presented a borderline UBT delta value. In 25 discordant samples, PCR targeting H. pylori DNA was performed to re-assess positivity and SAT accuracy was re-analysed: sensitivity, specificity, positive predictive value, negative predictive value, accuracy and AUC were 94%, 97%, 86%, 99%, 97% and 0.96, respectively. The new LIAISON® Meridian H. pylori SA SAT showed a good accuracy for diagnosis of H. pylori infection.

Clinical Evaluation of a Novel Stool Antigen Test Using Bioluminescent Enzyme Immunoassay for Detecting Helicobacter pylori

BACKGROUND

BLEIA ™ "EIKEN" Helicobacter pylori antigen (B[EIA]) is based on the bioluminescent enzyme immunoassay (BLEIA) method that was newly developed with high sensitivity in detecting Helicobacter pylori (H. pylori) antigen in feces.

METHODS

In the project for H. pylori screening and treatment in Saga Prefecture in 2019, 141 students received the stool H. pylori antigen test as a secondary test. For 141 students, a comparative test was conducted between B (EIA) and extracorporeal diagnostic agents that were marketed in Japan as of 2019. The detection performance of H. pylori ATCC43504 standard strain and H. pylori antigen in commercial human fecal specimens were conducted.

RESULTS

The comparison of B (EIA) with Quick Chaser ^TM H. pylori (Q [IC]) revealed positive and negative concordance ratios of B (EIA) to Q (IC) of 100.0% (110/110) and 71.0% (22/31), respectively. A comparative test was conducted between B (EIA) and extracorporeal diagnostic agents that were marketed in Japan as of 2019, and B (EIA) was most sensitive on "detecting H. pylori antigen of ATCC43504 standard strain" and "detecting H. pylori antigen in commercial human fecal specimens," compared with other kits. Nine dissociated specimens that were negative for Q (IC) and positive for B (EIA) were confirmed. The measured value of B (EIA) in the dissociation samples were 1.3-87.4 cutoff index in the range that can be evaluated as negative by other fecal H. pylori antigen test kits, all the dissociation samples were H. pylori antigen-positive cases, and finally the cause of result divergence was presumed as false negative due to insufficient sensitivity of Q (IC).

CONCLUSION

B (EIA) that is based on the BLEIA method, which applies firefly luciferase luminescence, is more sensitive than stool antigen test kits that are currently marketed in Japan and is very useful in diagnosing H. pylori infection, especially in situations where noninvasive tests are preferred, such as in children.

Evolution of Diagnostic Methods for Helicobacter pylori Infections: From Traditional Tests to High Technology, Advanced Sensitivity and Discrimination Tools

Rapid diagnosis and treatment application in the early stages of H. pylori infection plays an important part in inhibiting the transmission of this infection as this bacterium is involved in various gastric pathologies such as gastritis, gastro-duodenal ulcer, and even gastric neoplasia. This review is devoted to a quick overview of conventional and advanced detection techniques successfully applied to the detection of H. pylori in the context of a compelling need to upgrade the standards of the diagnostic methods which are currently being used. Selecting the best diagnostic method implies evaluating different features, the use of one or another test depending on accessibility, laboratories equipment, and the clinical conditions of patients. This paper aims to expose the diagnosis methods for H. pylori that are currently available, highlighting their assets and limitations. The perspectives and the advantages of nanotechnology along with the concept of nano(bio)sensors and the development of lab-on-chip devices as advanced tools for H. pylori detection, differentiation, and discrimination is also presented, by emphasizing multiple advantages: simple, fast, cost-effective, portable, miniaturized, small volume of samples required, highly sensitive, and selective. It is generally accepted that the development of intelligent sensors will completely revolutionize the acquisition procedure and medical decision in the framework of smart healthcare monitoring systems.

Accuracy of H. pylori fecal antigen test using fecal immunochemical test (FIT)

BACKGROUND

Gastric and colorectal cancer (CRC) are both one of the most common cancers worldwide. In many countries fecal immunochemical tests (FIT)-based CRC screening has been implemented. We investigated if FIT can also be applied for detection of H. pylori, the main risk factor for gastric cancer.

METHODS

This prospective study included participants over 18 years of age referred for urea breath test (UBT). Patients were excluded if they had used antibiotics/bismuth in the past 4 weeks, or a proton pomp inhibitor (PPI) in the past 2 weeks. Participants underwent UBT, ELISA stool antigen test in standard feces tube (SAT), ELISA stool antigen test in FIT tube (Hp-FIT), and blood sampling, and completed a questionnaire on user friendliness. UBT results were used as reference.

RESULTS

A total of 182 patients were included (37.4% male, median age 52.4 years (IQR 22.4)). Of these, 60 (33.0%) tested H. pylori positive. SAT and Hp-FIT showed comparable overall accuracy 71.1% (95%CI 63.2-78.3) vs. 77.6% (95%CI 70.4-83.8), respectively (p = 0.97). Sensitivity of SAT was 91.8% (95%CI 80.4-97.7) versus 94.2% (95%CI 84.1-98.9) of Hp-FIT (p = 0.98). Serology scored low with an overall accuracy of 49.7% (95%CI 41.7-57.7). Hp-FIT showed the highest overall user convenience.

CONCLUSIONS

FIT can be used with high accuracy and sensitivity for diagnosis of H. pylori and is rated as the most convenient test. Non-invasive Hp-FIT test is highly promising for combined upper and lower gastrointestinal (pre-) cancerous screening. Further research should investigate the clinical implications, benefits and cost-effectiveness of such an approach.

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.

Optimizing the searching for H. pylori in clinical practice with EndoFasterⓇ

BACKGROUND/AIM

H. pylori plays a major role in gastroduodenal diseases. Since its incidence is decreasing in developed countries, gastric biopsies were negative in several patients managed in clinical practice. We tested whether EndoFaster^Ⓡ - a device allowing real-time H. pylori detection by gastric juice analysis - may optimize the need of biopsies.

METHODS

In this prospective, multicentre study, the accuracy of EndoFaster^Ⓡ for H. pylori detection was computed by using histology of gastric biopsies as a gold standard.

RESULTS

Data of 525 consecutive patients were available, including 90 (17.1%) patients with infection. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy of EndoFaster^Ⓡ were 87%, 84%, 53%, 97% and 85%, respectively. The overall accuracy of test was not affected neither by ongoing proton pump inhibitor therapy nor by previous eradication therapy. By using EndoFaster^Ⓡ in our series, biopsy sampling could have been eventually avoided in a total of 279 patients, accounting for a reduction of 42.3%, accepting the risk of only 8 false negative cases.

CONCLUSIONS

The very high NPV of EndoFaster^Ⓡ might allow to safely halve the need of taking gastric biopsies in unselected patients managed in clinical practice, avoiding an unavailing consume of health resources.

Real-time EndoFaster improves Helicobacter pylori detection in chronic active gastritis

Helicobacter pylori is the most frequent cause of chronic active gastritis (CAG), namely the first step for gastric cancer development. When infection is not detected at histology, another test is advised. EndoFaster is novel device that reveal the presence of H. pylori by determining ammonium concentration in the gastric juice during endoscopy. We evaluated whether this test may improve etiological diagnosis in CAG patients. In 595 consecutive patients who underwent upper endoscopy gastric juice was analysed with EndoFaster and standard biopsies were taken. CAG with typical bacteria was detected in 102 (17.1%) patients, and CAG without H. pylori was found in 36 (6.3%) cases. EndoFaster detected the infection in 22 (61.1%) of these patients. Neither ongoing proton pump inhibitor therapy nor previous eradication therapy affect the test accuracy. By using EndoFaster, another test to search for the infection in H. pylori-negative CAG patients may be avoided in more than 60% of cases, impacting on both patients discomfort and health resources use.

Helicobacter pylori and Upper Endoscopy in Systemic Sclerosis: A Cross-sectional Study in the Real World

BACKGROUND/AIMS

A role for Helicobacter pylori in triggering systemic sclerosis (SSc) has been proposed, but data are conflicting. In previous studies, infection has been generally searched for by using serology. We designed this study to assess H. pylori prevalence in SSc patients with histology of gastric mucosa, considered the criterion standard for infection diagnosis.

METHODS

This cross-sectional study enrolled 30 SSc patients who complained of upper gastrointestinal symptoms. All underwent upper endoscopy with gastric biopsies. Endoscopic alterations were recorded, and gastric mucosa biopsies were used for both histological examination and searching for H. pylori. The role for proton-pump inhibitor (PPI) therapy was considered. Fisher exact test was used for statistical analysis.

RESULTS

Data of 28 SSc patients were available, 14 with ongoing PPI therapy. Helicobacter pylori infection at histology was detected in 14.3% patients, and it equally occurred in patients with or without PPI therapy. Erosive esophagitis/Barrett esophagus was detected in 26.6% of cases. Among patients with PPI therapy, 30% received half dose only. The prevalence of intestinal metaplasia was low (14.3%). Endoscopic esophageal alterations were significantly more frequent in those patients showing anti-Scl70 antibody positivity.

CONCLUSIONS

This study showed that prevalence of H. pylori is very low in SSc patients, so that it seems not having a role in triggering SSc. Management of gastroesophageal diseases in SSc patients needs to be improved, and looking to the autoimmune profile may be of help. Thus, collaboration between rheumatologist and gastroenterologist is highly recommended.

Noninvasive Helicobacter pylori Diagnostic Methods in Indonesia

Although the prevalence of Helicobacter pylori infection in Indonesia is lower than that in other countries, H. pylori is still an essential pathogen associated with severe gastric mucosal damage and dyspeptic symptoms. Invasive diagnostic methods are not ideal due to the lack of endoscopic centers and high costs without full coverage by social insurance. Among the noninvasive methods, the urea breath test is widely available in Indonesia and has been suggested as the primary option to ensure the successful eradication of H. pylori. There has been no local validation for the urea breath test utilizing ¹³C or ¹⁴C. The stool antigen test is inexpensive and suitable for use in active infections before and after eradication; however, customs and habits are obstacles to delivering fresh stool on time. Only polyclonal antibodies and qualitative stool antigen test kits with low sensitivity are available. Serology is a widely validated method and has good accuracy, but it cannot distinguish between active and inactive infections. According to our observations, serology is the main choice of experts and patients, as it is simple, inexpensive and widely known. The urine test is an alternative for reducing costs and endoscopic workload, with high accuracy but low sensitivity. Further studies are necessary to prove the validity of the urine test to be used throughout Indonesia, especially in areas with a low prevalence of H. pylori infection. In conclusion, the validated urea breath test and the stool antigen test are considered noninvasive practical approaches for the detection of H. pylori infection in Indonesia, with serological and urine tests as alternatives.

Sequential Helicobacter pylori eradication therapy in Myanmar; a randomized clinical trial of efficacy and tolerability

BACKGROUND AND AIM

There is little published research to examine the best approach to the management of Helicobacter pylori in Myanmar. This study aimed to determine the relative efficacy and tolerability of sequential eradication therapy compared to Myanmar's current recommendation of a concomitant four drug regimen.

METHODS

Patients were screened for H. pylori using monoclonal Stool Antigen Testing (SAT). Those testing positive were randomized 1:1 to receive receive Myanmar's first-line regimen of 14 days of concomitant rabeprazole, clarithromycin, amoxycillin and tinidazole (140 pills, cost US$23) or 10 days of sequential rabeprazole, clarithromycin, amoxycillin and tinidazole (60 pills, cost US$10). Adherence and adverse effects were recorded, and the efficacy of the regimens assessed with repeat SAT.

RESULTS

Of the 1011 patients screened for H. pylori infection, 313 (31%) tested positive. There was no statistical difference in the cure rates of the two regimens in either intention-to-treat: 128/157 (82%; 95% confidence interval (CI): 75-87%) receiving sequential therapy versus 123/156 (79%; 95% CI: 72-85%) receiving concomitant therapy (P = 0.55) or per-protocol analysis: 125/131 (95%; 95% CI: 90-98) receiving sequential therapy versus 121/130 (93%; 95% CI: 87-96) receiving concomitant therapy (P = 0.42). Side effects of therapy were reported in 54/157 (47%) patients taking sequential therapy compared with 62/156 (53%) taking concomitant therapy, but this difference did not reach statistical significance (P = 0.33).

CONCLUSIONS

In this high-burden, resource-poor setting, less expensive sequential therapy was as effective and as well tolerated as the currently recommended concomitant four drug regimen for eradication of H. pylori.

Guidelines for the management of Helicobacter pylori infection in Japan: 2016 Revised Edition

BACKGROUND

Since "Helicobacter pylori (H. pylori) infection" was set as the indication in the Japanese Society for Helicobacter Research (JSHR) Guidelines 2009, eradication treatment for H. pylori gastritis is covered under insurance since 2013 in Japan, and the number of H. pylori eradication has rapidly increased. Under such circumstances, JSHR has made the third revision to the "Guidelines for diagnosis and treatment of H. pylori infection" for the first time in 7 years.

METHODS

The Guideline Committee held 10 meetings. Articles published between the establishment of the 2009 Guidelines and March 2016 were reviewed and classified according to the evidence level; the statements were revised on the basis of this review. After inviting public comments, the revised statements were finalized using the Delphi method.

RESULTS

There was no change in the basic policy that H. pylori infectious disease is an indication for eradication. Other diseases presumed to be associated with H. pylori infection were added as indications. Serum pepsinogen level, endoscopic examination, and X-ray examination were added to the diagnostic methods. The effects of 1-week triple therapy consisting of potassium-competitive acid blocker (P-CAB), amoxicillin, and clarithromycin have improved, and high eradication rates can also be expected with proton pump inhibitors (PPI) or P-CAB combined with amoxicillin and metronidazole. If the susceptibility test is not performed, the triple PPI or P-CAB/amoxicillin/metronidazole therapy should be chosen, because the PPI/amoxicillin/metronidazole combination demonstrated a significantly higher eradication rate than PPI/amoxicillin/clarithromycin. In the proposal for gastric cancer prevention, we divided gastric cancer prevention measures by age from adolescent to elderly, who are at an increased gastric cancer risk, and presented measures for gastric cancer prevention primarily based on H. pylori eradication.

CONCLUSION

We expect the revised guidelines to facilitate appropriate interventions for patients with H. pylori infection and accomplish its eradication and prevention of gastric cancer.

Evaluation of a Novel Stool Antigen Rapid Test Kit for Detection of Helicobacter pylori Infection

The Quick Chaser H. pylori (QCP), which is a novel antigen detection kit for Helicobacter pylori, was developed recently. The previous examination kits targeted the catalase of H. pylori; however, this new test kit, to the best of our knowledge, is the first kit to target the flagellar protein of H. pylori The present study aimed to evaluate the efficacy of QCP compared with that of the already commercially available rapid test kit Testmate Rapid Pylori Antigen (TRP). TRP and QCP were utilized in 71 participants. The positive and negative concordance ratios of QCP to TRP were 100% (57/57) and 92.9% (13/14), respectively. Sensitivity based on the rapid urease test and culture test was 92.3%. Results of the dilution sensitivity test showed that QCP was eight times more sensitive to an H. pylori standard strain and the clarithromycin (CAM)-resistant clinical isolate and four times more sensitive to a CAM-susceptible clinical isolate than TRP. For the cross-reactivity test, 27 strains that exist in human feces, such as the Helicobacter genus, Bifidobacterium genus, Lactobacillus genus, and other resident bacteria, were selected. The results obtained using QCP were all negative, and no cross-reaction was observed. In conclusion, compared with TRP, QCP can detect H. pylori using clinical specimens with high sensitivity, regardless of CAM susceptibility and tolerance. No cross-reactivity was observed with other intestinal bacteria in humans. The kit is considered extremely useful in clinical settings.

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.

Designing a novel ELISA method based on CagA, NapA recombinant antigens to increase sensitivity and specificity of Helicobacter pylori whole cell antigen detection

AIM

In this research, we designed a direct Enzyme Linked Immunoassay method to detect Helicobacter pylori antigens in stool specimens.

BACKGROUND

Helicobacter pylori infection as the worldwide problem is related to many gastrointestinal disorders such as gastritis, gastric cancer, non-ulcer disease, peptic ulcer disease and duodenal ulcer.

METHODS

We produced and purified recombinant CagA and NapA antigens in Escherichia coli and extracted their antibodies from a panel of positive sera specimens. We designed a novel enzyme linked immunoassay direct method in combination with the whole cell for the qualitative and quantitative detection of Helicobacter pylori antigens in human stool. Assay performance was evaluated by histopathology staining and urease activity.

RESULTS

The sensitivity and specificity of assay was determined as 91.7 [95% confidence interval: 89.3-95.6%] and 93.1% [95% CI: 91.2-96.4%], respectively. Novel ELISA exhibits enhanced sensitivity and specificity of Helicobacter pylori detection in comparison with another commercially available kit.

CONCLUSION

Combination of the recombinant antigens and whole cell of Helicobacter pylori in immunoassay designing is a new approach about early diagnosis, treatment and fallowing up of the Helicobacter pylori infected patients, especially in peptic cancer cases.

Diagnostic Methods of Helicobacter pylori Infection for Epidemiological Studies: Critical Importance of Indirect Test Validation

Among the methods developed to detect H. pylori infection, determining the gold standard remains debatable, especially for epidemiological studies. Due to the decreasing sensitivity of direct diagnostic tests (histopathology and/or immunohistochemistry [IHC], rapid urease test [RUT], and culture), several indirect tests, including antibody-based tests (serology and urine test), urea breath test (UBT), and stool antigen test (SAT) have been developed to diagnose H. pylori infection. Among the indirect tests, UBT and SAT became the best methods to determine active infection. While antibody-based tests, especially serology, are widely available and relatively sensitive, their specificity is low. Guidelines indicated that no single test can be considered as the gold standard for the diagnosis of H. pylori infection and that one should consider the method's advantages and disadvantages. Based on four epidemiological studies, culture and RUT present a sensitivity of 74.2–90.8% and 83.3–86.9% and a specificity of 97.7–98.8% and 95.1–97.2%, respectively, when using IHC as a gold standard. The sensitivity of serology is quite high, but that of the urine test was lower compared with that of the other methods. Thus, indirect test validation is important although some commercial kits propose universal cut-off values.

Helicobacter pylori Antibody Titer and Gastric Cancer Screening

The "ABC method" is a serum gastric cancer screening method, and the subjects were divided based on H. pylori serology and atrophic gastritis as detected by serum pepsinogen (PG): Group A [H. pylori (-) PG (-)], Group B [H. pylori (+) PG (-)], Group C [H. pylori (+) PG (+)], and Group D [H. pylori (-) PG (+)]. The risk of gastric cancer is highest in Group D, followed by Groups C, B, and A. Groups B, C, and D are advised to undergo endoscopy, and the recommended surveillance is every three years, every two years, and annually, respectively. In this report, the reported results with respect to further risk stratification by anti-H. pylori antibody titer in each subgroup are reviewed: (1) high-negative antibody titer subjects in Group A, representing posteradicated individuals with high risk for intestinal-type cancer; (2) high-positive antibody titer subjects in Group B, representing active inflammation with high risk for diffuse-type cancer; and (3) low-positive antibody titer subjects in Group C, representing advanced atrophy with increased risk for intestinal-type cancer. In these subjects, careful follow-up with intervals of surveillance of every three years in (1), every two years in (2), and annually in (3) should be considered.

Evaluation of Exalenz Bioscience's BreathID for Helicobacter pylori detection

Carbon-labeled urea breath tests, which have high sensitivity and specificity, are the preferred method used in epidemiological studies, screening dyspeptic patients and assessing eradication or recurrence of Helicobacter pylori infection. The principle of the (13)C-urea breath test relies upon the ability of the H. pylori urease to hydrolyze the orally administered (13)C-urea. The BreathID (Exalenz Bioscience Inc., Union, NJ, USA) provides a competitive solution for breath testing, including unique features such as automatic continuous breath collection and analysis. This is an unattended convenient test, with no human error as the correct part of the breath is collected and patients' assistance is not required. The test results are available in real time at the point of care and enable shortened breath testing procedures. Additionally, several studies showing expanded utility of the BreathID in pediatrics, after therapy and during proton pump inhibitors intake, further support the safety and performance of the BreathID in the diagnosis of H. pylori.

Chronic gastritis - an update

Helicobacter pylori is the main aetiologic factor for chronic gastritis worldwide. The degree of inflammation and the evolution of this form of chronic gastritis can vary largely depending on bacterial virulence factors, host susceptibility factors and environmental conditions. Autoimmune gastritis is another cause of chronic inflammation in the stomach, which can occur in all age groups. This disease presents typically with vitamin B12 deficiency and pernicious anaemia. The presence of anti-parietal cell antibodies is highly specific for the diagnosis. The role of H. pylori as a trigger for autoimmune gastritis remains uncertain. Other rare conditions for chronic gastritis are chronic inflammatory conditions such as Crohn's disease or on the background of lymphocytic or collagenous gastroenteropathies.

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.

Epidemiology and diagnosis of Helicobacter pylori infection

Medline, PubMed and the Cochrane databases were searched on epidemiology and diagnosis of Helicobacter pylori for the period of April 2011-March 2012. Several studies have shown that the prevalence of H. pylori infection is decreasing in adults and children in many countries. Various diagnostic tests are available, and most of them have high sensitivity and specificity. The Maastricht IV/Florence consensus report states that the urea breath test using (13)C urea remains the best test to diagnose H. pylori infection. Among the stool antigen tests, the ELISA monoclonal antibody test is recommended. All these tests were used, either as a single diagnostic test or in combination, to investigate H. pylori infection among different populations throughout the world. Of particular interest, current improvements in high-resolution endoscopic technologies enable increased diagnostic accuracy for the detection of H. pylori infection, but none of these techniques, at present, are specific enough for obtaining a real-time diagnosis of H. pylori infection.