Diagnosis of Helicobacter pylori infection

The Diagnostic Tests for Detection of Helicobacter pylori Infection

Helicobacter pylori causes one of the most common infections in human populations. The role of this bacterium in chronic gastritis, gastric ulcer, gastric cancer, as well as extra-digestive diseases such as ischemic heart disease and chronic obstructive pulmonary diseases, is well known. Prevention and control of these diseases can occur by early diagnosis and eradication of H. pylori infection. At present, different methods have been established to detect H. pylori infection. The biopsy-based tests, which are known as invasive methods, such as rapid urease test and histology, have the highest specificity among the others. Similarly, culture of biopsy samples is used for diagnosis of H. pylori infection. It has a high specificity value, and also allows us to perform antibiotic sensitivity testing. On the contrary, polymerase chain reaction and other molecular methods have good sensitivity and specificity, and can be used for detection of H. pylori infection, its virulence factors, and eradication success after treatment. While serological tests are more appropriate for epidemiological studies, their main weakness for clinical use is low specificity. Overall, specificity and sensitivity, cost, usefulness, and limitation of tests should be considered for selection of detection methods of H. pylori in each country.

First-line antibiotic therapy in Helicobacter pylori-negative low-grade gastric mucosa-associated lymphoid tissue lymphoma

First-line antibiotic treatment for eradicating Helicobacter pylori (HP) infection is effective in HP-positive low-grade gastric mucosa-associated lymphoid tissue lymphoma (MALToma), but its role in HP-negative cases is uncertain. In this exploratory retrospective study, we assessed the outcome and potential predictive biomarkers for 25 patients with HP-negative localized gastric MALToma who received first-line HP eradication (HPE) therapy. An HP-negative status was defined as negative results on histology, rapid urease test, 13C urea breath test, and serology. We observed an antibiotic response (complete remission [CR], number = 8; partial remission, number = 1) in 9 (36.0%) out of 25 patients. A t(11;18)(q21;q21) translocation was detected in 7 (43.8%) of 16 antibiotic-unresponsive cases, but in none of the 9 antibiotic-responsive cases (P = 0.027). Nuclear BCL10 expression was significantly higher in antibiotic-unresponsive tumors than in antibiotic-responsive tumors (14/16 [87.5%] vs. 1/9 [11.1%]; P = 0.001). Nuclear NF-κB expression was also significantly higher in antibiotic-unresponsive tumors than in antibiotic-responsive tumors (12/16 [75.0%] vs. 1/9 [11.1%]; P = 0.004). A substantial portion of patients with HP-negative gastric MALToma responded to first-line HPE. In addition to t(11;18)(q21;q21), BCL10 and NF-κB are useful immunohistochemical biomarkers to predict antibiotic-unresponsive status in this group of tumors.

Clinical significance of various diagnostic techniques and emerging antimicrobial resistance pattern of Helicobacter Pylori from Gastric Biopsy Samples

BACKGROUND

There is no single technique that can meet the criteria in identification of Helicobacter pylori. The diagnosis is important asantimicrobial resistance is frequently observed and associated with treatment failure. The present study was conducted to evaluate diagnostic tests for identification of H pylori and to assess their antimicrobial resistance pattern.

MATERIALS AND METHODS

Biopsies of gastric tissue from 200 patients with disorders of the upper gastrointestinal tract were studied for detection of H pylori by various methods like culture, H and E staining and urease test. Antimicrobial susceptibility testing was carried out by Kirby Bauer's disc diffusion method.

RESULTS

Out of 200 patients, H pylori was detected by rapid urease test, H and E staining and culture in 26.5%, 14.5% and 2.5% cases respectively. H and E was taken as the gold standard. Sensitivity of urease test was 76.6% and of culture 13.3%. Specificity of urease was 81.7% in comparison with culture which showed 99.4% specificity. Metronidazole (05) showed high level of resistance followed by amoxicillin (03) and norfloxacillin (03). Tetracycline, erythromycin, levofloxacin and cotrimoxazole showed one resistance each to H pylori.

CONCLUSION

H and E is taken as the gold standard according to CDC. Urease test is a better screening procedure than culture. H pylori resistance to metronidazole in our zone was highest. This is due to general and extensive use of metronidazole for other infectious diseases. Our study suggests need for a systematic approach to determine antibiogram of the strains before considering the drug regimens.

Value of the "Test & Treat" Strategy for Uninvestigated Dyspepsia at Low Prevalence Rates of Helicobacter pylori in the Population

BACKGROUND AND AIM

In populations with a low prevalence rate of Helicobacter pylori (H. pylori) infection from Western countries, guidelines for the management of uninvestigated dyspepsia generally recommend that the "test and treat" strategy should be avoided in favor of empiric proton-pump inhibitor therapy in younger patients (on average < 50 years of age) without alarm symptoms and signs. The prevalence of H. pylori infection has fallen from about 30% to about 10% in Sweden and other countries. We aimed to explore whether the rationale for test and treat is relevant in contemporary clinical practice.

MATERIALS AND METHODS

In settings with an infection rate in the adult population of 30% and 10%, we modeled the positive and negative predictive values for indirect (nonendoscopy) tests on current H. pylori infection with a presumed sensitivity and specificity of 95%. We then calculated the difference in false-negative and false-positive test outcome, and eradication prescription rates in the two scenarios.

RESULTS

While the positive predictive value for the test decreased from 0.89 to 0.68 when the prevalence of H. pylori fell from 30% to 10%, there were only 1% more false-negative tests and 1% less false-positive tests. The eradication prescription rate would decrease by 18% with a 10% prevalence rate.

CONCLUSION

The recommendation to stop applying "test and treat" at lower prevalence rates of H. pylori should be reconsidered. The test and treat strategy is the preferred approach for most patients who present with dyspepsia.

Antral gastritis caused by Helicobacter pylori infection in the pediatric age group is associated with increased mesenteric lymph node dimension observed by ultrasonography

BACKGROUND

To find out if transabdominal ultrasonography (US) may have a predictive role for detection of antral gastritis and Helicobacter pylori (HP) infection in the antrum of pediatric age group.

METHODS

A total of 91 (63.6%) patients and 52 (36.4%) controls were allocated into two groups as follows: Group 1 (n=91): patients with complaints and endoscopic findings consistent with gastritis and documented HP infection; Group 2 (n=52): patients with complaints and endoscopic findings consistent with gastritis in the absence of documented HP infection. These two groups were compared in terms of demographics and biggest mesenteric lymph node detected, muscularis mucosa thickness, submucosal thickness, muscularis propria thickness, and total gastric wall thickness.

RESULTS

The two groups exhibited no statistically significant difference with respect to age (P=0.747), and presenting symptoms (P=0.982). However, the mesenteric lymph node dimension was significantly increased in Group 1 (P=0.039). Median mesenteric lymph node dimension was 12.9 (±15.4) mm in Group 1, while 11.0 (±12.8) mm in Group 2. No significant difference was observed between groups in terms of muscularis mucosa thickness (P=0.243), submucosal thickness (P=0.174), muscularis propria thickness (P=0.356), and total gastric wall thickness (P=0.223).

CONCLUSIONS

Antral gastritis caused by HP infection in the pediatric age group is associated with increased mesenteric lymph node dimension observed by US.

Diagnosis of Helicobacter pylori infection by invasive and noninvasive tests

Although several invasive and noninvasive tests have been developed for the diagnosis of Helicobacter pylori infection, all of the tests have their limitations. We conducted a study to investigate and compare the suitability of rapid urease test (RUT), serology, histopathology and stool antigen tests with polymerase chain reaction (PCR) for detection of H. pylori, and correlate the diagnostic methods with PCR. Eighty nine patients (61 adults, 28 children) referred to the Firoozgar Hospital and Children Medical Center Hospital for diagnostic upper gastrointestinal endoscopy entered to the study and noninvasive tests such as immunoassay for serological antibodies against H. pylori and detection of its antigen in feces were measured. The biopsies were utilized for histological examination, RUT and PCR. The H. pylori statuses were evaluated by the positivity of ureC PCR in biopsy specimens and 53 subjects had H. pylori positive result. Histopathology showed high overall performance in adults and children with sensitivity and specificity 100% and 90%, respectively. Sensitivity, specificity, and accuracy for stool antigen test were 87.8%, 75% and 82%, respectively. Correlation of RUT, serology (IgG), histopathology and stool antigen tests with PCR were 0.82, 0.32, 0.91 and 0.63, respectively. In conclusion, the RUT and histopathology are as accurate as the PCR of biopsy and stool antigen test can consider as appropriate noninvasive test for detection of H. pylori infection.

Evaluation of diagnostic methods for the detection of Helicobacter pylori in gastric biopsy specimens of dyspeptic patients

Helicobacter pylori infects nearly 50% of the world’s population. This microorganism is accepted as the most important agent of gastritis and as a risk factor for peptic ulcer disease and gastric adenocarcinoma. Currently many diagnostic methods exist for detecting H. pylori, however they all have limitations, thus it is recommend a combination of at least two methods. The aim of this study was to evaluate diagnostic methods, such as in-house urease test, culture and Polymerase Chain Reaction (PCR), for the detection of the H. pylori in gastric biopsy specimens of 144 dyspeptic patients, using as gold standard the association between histology and rapid urease test. According to the gold standard used in this study, 48 (33.3%) patients were infected with H. pylori, while 96 (66.7%) were classified as not infected. The in-house urease test and the PCR were the most sensitive methods (100%), followed by culture (85.4%). However, the inhouse urease test and the culture were the most specific (100%), followed by PCR (75%). In conclusion, this study showed that, in comparison with the combination of histology and rapid urease test, the in-house urease test and the PCR presented 100% of sensitivity in the diagnosis of gastric infection by H. pylori, while the in-house urease test and the culture reached 100% of specificity. These finding suggest that the combination of two or more methods may improve the accuracy of the H. pylori detection.

Utility of stool sample-based tests for the diagnosis of Helicobacter pylori infection in children

OBJECTIVE

Helicobacter pylori antigen or DNA in stool are meant to detect the bacteria; however, in children the colonization of the gastric mucosa by H pylori is usually weak and fecal excretion of antigen or DNA varies considerably, challenging the utility of these tests in this age group. The aim of the present study was to carry out a systematic review and meta-analysis to evaluate the performance of stool H pylori DNA and antigen tests for the diagnosis of infection in children.

METHODS

We conducted a systematic review and meta-analysis to assess the accuracy of stool tests for diagnosis of H pylori infection in children. We searched PubMed, EMBASE, and LILACS databases. Selection criteria included participation of at least 30 children and the use of a criterion standard for H pylori diagnosis. In a comprehensive search, we identified 48 studies.

RESULTS

Regarding antigen-detection tests, enzyme-linked immunosorbent assay (ELISA) monoclonal antibodies showed the best performance, with sensitivity and specificity of 97%, positive likelihood ratio (LR+) of 29.9, and negative likelihood ratio (LR-) of 0.03. ELISA polyclonal antibodies had sensitivity of 92%, specificity of 93%, LR+ of 16.2, LR- of 0.09, and high heterogeneity (P < 0.0001). One-step monoclonal antibody tests demonstrated sensitivity of 88%, specificity of 93%, LR+ of 10.6, and LR- of 0.11. For DNA detection, polymerase chain reaction-based test showed sensitivity of 80.8%, specificity of 98%, LR+ of 17.1, and LR- of 0.18.

CONCLUSIONS

Detection of H pylori antigen in stools with ELISA monoclonal antibodies is a noninvasive efficient test for diagnosis of infection in children. One-step tests showed low accuracy and more studies are needed to obtain a useful office-based screening test. The available molecular tests are still unreliable.

Evaluation of a new antigen for diagnosis of Helicobacter pylori infection in stool of adult and children

BACKGROUND

Nowadays, there is an increasing interest in noninvasive methods to diagnose Helicobacter pylori infection. Indeed, they can profitably replace endoscopy in predicting the diagnosis. The stool antigen test for H. pylori is a noninvasive immunoassay to diagnose active infection with this bacterium in human fecal samples. The aim of this study was detection of alkyl hydroperoxide reductase protein (AhpC) antigen by immunoblotting in stool samples for diagnosis of H. pylori.

MATERIALS AND METHODS

Chromosomal DNA from H. pylori was isolated. AhpC gene was amplified by PCR, These amplicons were cloned into pTZ57R/T cloning vector then subcloned into pQE30 expression vector and overexpressed using isopropyl-beta-D-thiogalactopyranoside in E. coli M15. AhpC protein was purified by affinity chromatography. Rabbits were immunized with the purified AhpC protein for the production of antibodies. To determine the accuracy of the test for diagnosing H. pylori infection from stool, we evaluated 84 patients (6-81 years old) using Western blot analysis by rabbit anti-AhpC antibody. Positive rapid urease test on biopsy samples was considered as the gold standard.

RESULTS

AhpC gene was overexpressed, and AhpC protein was purified. Rabbit anti-AhpC antibody produced after immunization with the purified AhpC protein. By immunoblotting, we detected AhpC protein in the positive stool samples. The test showed a 83.3% sensitivity (95% CI: 69.8-92.5%) and a 91.7% specificity (95% CI: 77.5-98.2). Among the children, the sensitivity was 88.2% (95% CI: 63.6-98.5) and the specificity was 100% (95% CI: 69.2-100); in adults, the sensitivity and specificity were 80.6% (95% CI: 62.5-92.5) and 88.5% (95% CI: 69.8-97.6), respectively.

CONCLUSIONS

Using of AhpC antigen for diagnosis of H. pylori infection is a useful noninvasive method, accurate in adolescents and children, and can be used for the development of a stool antigen detection kit for H. pylori.

Unreliability of results of PCR detection of Helicobacter pylori in clinical or environmental samples

The aim of this study was to compare published Helicobacter pylori primer pairs for their ability to reliably detect H. pylori in gastric biopsy specimens and salivary samples. Detection limits of the 26 PCR primer pairs previously described for detection of H. pylori DNA in clinical samples were determined. Sensitivity and specificity were determined using primers with detection limits of <100 CFU/ml using 50 H. pylori-positive and -negative (by concordance by culture and histology) coded gastric biopsy specimens. These results were then confirmed with gastric biopsy specimens and saliva from patients with confirmed H. pylori status. Five of the twenty-six previously reported primer pairs (HP64-f/HP64-r, HP1/HP2, EHC-U/EHC-L, VAG-F/VAG-R, and ICT37/ICT38) had detection limits of <100 CFU/ml in the presence of gastric tissue. None had 100% specificity or sensitivity; all produced false-positive results. The HP64-f/HP64-r for ureA and HP1/HP2 for 16S rRNA individually had sensitivities and specificities of >90% with gastric biopsy specimens. No combinations of primer pairs improved the results. Using these five primer pairs, 54% of the positive saliva samples were determined to be false positive; both the HP64-f/HP64-r and the HP1/HP2 sets produced false positives with saliva. We conclude that clinicians should not rely on results using current PCR primers alone to decide the H. pylori status of an individual patient or as a basis for treatment decisions. The results of studies based on PCR identification of H. pylori in environmental samples should be viewed with caution. Possibly, specific primers sets can be identified based on the presence of multiple putative virulence factor genes.

Antibody-based detection tests for the diagnosis of Helicobacter pylori infection in children: a meta-analysis

Background

Numerous serologic tests are available for the diagnosis of H. pylori infection in children. Common designs of antibody-based detection tests are ELISA and Western Blot (WB). For developing countries with limited laboratory resources and access, ELISA would be the preferred method because of its simplicity, lower cost and speed. Although in adults ELISA has proven to be highly accurate in diagnosing H. pylori infection; in children, it has shown variable accuracy.

Methods/Findings

We conducted a systematic review and meta-analysis to assess the accuracy of antibody-based detection tests for the diagnosis of H. pylori infection in children. Selection criteria included participation of at least 30 children and the use of a gold standard for H. pylori diagnosis. In a comprehensive search we identified 68 studies. Subgroup analyses were carried out by technique, immunoglobulin class, and source of test (commercial and in-house). The results demonstrated: 1) WB tests showed high overall performance, sensitivity 91.3% (95% CI, 88.9–93.3), specificity 89% (95% CI, 85.7–91.9), LR+ 8.2 (95% CI, 5.1–13.3), LR− 0.06 (95% CI, 0.02–0.16), DOR 158.8 (95% CI, 57.8–435.8); 2) ELISA-IgG assays showed low sensitivity 79.2% (95% CI, 77.3–81.0) and high specificity (92.4%, 95% CI, 91.6–93.3); 3) ELISA commercial tests varied widely in performance (test for heterogeneity p<0.0001); and 4) In-house ELISA with whole-cell antigen tests showed the highest overall performance: sensitivity 94% (95% CI, 90.2–96.7), specificity 96.4% (95% CI, 94.2–97.9), LR+ 19.9 (95% CI, 7.9–49.8), LR− 0.08 (95% CI, 0.04–0.15) DOR 292.8 (95% CI, 101.8–841.7).

Conclusions/Significance

WB test and in-house ELISA with whole-cell antigen tests are the most reliable tests for the diagnosis of H. pylori infection in children. Antigens obtained from local strains of the community could partially explain the good overall accuracy of the in-house ELISA. Because of its cost and technical demands, in-house ELISA might be more suitable for use in developing countries.

Helicobacter pylori stool antigen (HpSA) tests in children before and after eradication therapy: comparison of rapid immunochromatographic assay and HpSA ELISA

The rapid immunochromatography for Helicobacter pylori (H. pylori) stool antigen (rapid HpSA) test is a recently-developed method for detection of H. pylori infection. The objective of this study was to assess the pre and post-eradication diagnostic accuracy of the rapid HpSA test compared with the conventional HpSA immunoassay (HpSA ELISA) in children. Sensitivity, specificity, positive predictive value, and negative predictive value for the rapid HpSA test were 94.6, 98.4, 94.6, and 98.4%, respectively, and those for the HpSA ELISA were 94.6, 96.1, 87.5, and 98.4%, respectively. No significant difference was observed between the sensitivity and specificity of the two HpSA tests in children (P = 1.000 and P = 0.250) or the sensitivity and specificity of the two HpSA tests pre and post-eradication therapy (P = 1.000 and P = 1.000). The rapid HpSA and HpSA ELISA are reliable methods of detection of H. pylori infection in the pediatric population before and after eradication therapy.

Evaluation of a novel monoclonal-based antigen-in-stool enzyme immunoassay (Premier Platinum HpSA PLUS) for diagnosis of Helicobacter pylori infection in Vietnamese children

BACKGROUND

Helicobacter pylori infection is difficult to diagnose in children, especially in developing countries where noninvasive methods such as urea breath test are often not available. We evaluate the sensitivity and specificity of a new monoclonal antibody-based antigen-in-stool enzyme immunoassay (Premier Platinum HpSA PLUS) for diagnosis of H. pylori infection in Vietnamese children.

MATERIALS AND METHODS

Sensitivity of the antigen-in-stool test was evaluated in 232 children, 3-15 years of age, who were positive for H. pylori infection by culture from biopsies. For evaluation of the specificity 98 children of similar age with nongastrointestinal conditions and who were negative for H. pylori infection by serologic assays were included with blood and stool samples.

RESULTS

Of the 232 culture-positive children, 224 were also positive by Premier Platinum HpSA PLUS. Of the 98 control children, 93 were H. pylori negative also in the stool test. The sensitivity of Premier Platinum HpSA PLUS was thus 96.6% (95% CI 93.3-98.5) and the specificity was 94.9% (95% CI 88.5-98.3).

CONCLUSIONS

The findings have demonstrated Premium Platinum HpSA PLUS to be a reliable method for detection of H. pylori infection also in children in our area.

Use of NSAIDs and infection with Helicobacter pylori--what does the rheumatologist need to know?

OBJECTIVES

NSAID-induced gastroduodenal lesions are a frequent and potentially serious health problem in patients with rheumatic diseases. Helicobacter pylori (H. pylori) has also been recognized as a major risk factor for the development of ulcer disease. However, the role of H. pylori in the pathogenesis of NSAID-induced gastroduodenal lesions has remained controversial, and there is currently no clear consensus on the management of NSAID users who are infected with H. pylori.

METHODS

To clarify this situation we have performed a systematic literature search to find randomized controlled trials comparing the efficacy of eradication in patients receiving NSAIDs to prevent ulcer development.

RESULTS

Seven randomized controlled trials and one meta-analysis were identified. There were three papers on NSAID-naive patients. According to this data, NSAID-naive users benefit from testing for H. pylori infection and subsequent H. pylori eradication therapy prior to the initiation of NSAID. In contrast, H. pylori eradication alone does not protect chronic NSAID users with recent ulcer complications from further gastrointestinal (GI) events. To prevent recurrent ulcer bleeding long-term acid suppressive therapy is needed.

CONCLUSIONS

In conclusion, ulcer risk reduction after H. pylori eradication therapy is clearly more marked in patients beginning NSAID therapy than in patients who were already receiving and tolerating NSAID therapy. Thus, the management of H. pylori infection and the prevention of GI complications in NSAID users need to be individualized on the basis of recently published data.

Progress in developing accurate tests for the diagnosis of Helicobacter pylori infection

Helicobacter pylori is a chronic infectious agent as defined the major pathogen causing gastritis, gastric and duodenal ulcer, gastric carcinoma and mucosa-associated lymphoid tissue lymphoma, however little is known about its role in functional dyspepsia. H. pylori is the only microorganism known to inhabit the human stomach and the gastric mucosal cells. Chronic H. pylori infection of the stomach is increasingly recognized as a major risk factor for the development of gastroduodenal disease. H. pylori can be detected by non-invasive and invasive methods, the latter requiring endoscopy.

Reversal of migraine symptoms by Helicobacter pylori eradication therapy in patients with hepatitis-B-related liver cirrhosis

Helicobacter pylori infection might be associated with vascular diseases, such as primary Raynaud phenomenon and coronary heart diseases. The possible mechanism might be due to H. pylori antigens causing intermittent vasospasm of arterioles, which also played roles in the development of liver cirrhosis. Migraine, a functional vascular disease, was observed in many patients with cirrhosis in the clinic. This study aimed to assess the effects of H. pylori eradication on migraine symptoms in patients with hepatitis-B-virus-related cirrhosis. The results clearly showed that the intensity, duration, and frequency of attacks of migraine were significantly reduced in all the patients in whom H. pylori has been eradicated. Thus, the study pushed further insight into the mechanisms of migraine pathogenesis.