A rapid serologic test and immunoblotting for the detection of Helicobacter pylori infection in children

Diagnostic Validity of a Serological Test with the Current Infection Marker in Thai Adults before and after Helicobacter pylori Eradication Therapy

Helicobacter pylori infection poses significant health risks, such as gastric adenocarcinoma, necessitating accurate diagnosis and effective treatment in primary care. This study evaluated the diagnostic efficacy of the serological current infection marker (CIM) test in identifying current H. pylori infection. The CIM test samples from 159 participants undergoing gastroscopy were collected, and H. pylori-positive outpatients received triple therapy based on histology or rapid urease test results. Following treatment, 45 patients underwent a 13C-urea breath test and the CIM test for eradication assessment. For pre-eradication, the CIM test demonstrated 89.6% sensitivity, 95.7% specificity, 93.8% positive predictive value, 92.6% negative predictive value, and 93.1% accuracy. Following post-eradication, the CIM test exhibited sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 71.4%, 92.1%, 62.5%, 94.6%, and 88.9%, respectively, using the 13C-urea breath test as the reference standard. The CIM test showcased commendable diagnostic performance, emphasizing its efficacy in both pre- and post-eradication scenarios. Notably, the accuracy, non-invasiveness, user-friendliness, and cost-effectiveness of the CIM test advocate for its recommendation as a preferred diagnostic tool in primary care settings for H. pylori infection detection.

Seroreactivity to Helicobacter pylori antigens as a risk indicator of gastric cancer

BACKGROUND

Multiple etiologic factors are suspected to cause gastric cancer, the most important of which is infection with virulent types of Helicobacter pylori.

MATERIALS AND METHODS

We have compared 102 gastric cancer patients with 122 non-ulcer, non-cancer dyspeptic patients. Gastric specimens were evaluated for H. pylori infection by tissue-based detection methods. Patient sera underwent antigen-specific ELISA and western blotting using a Helicoblot 2.1 kit and antibody responses to various H. pylori antigens were assessed.

RESULTS

The absolute majority (97-100%) of both groups were H. pylori seropositive. Multivariate regression analysis demonstrated serum antibodies to the low molecular weight 35kDa protein to be protective and reduce the risk of gastric cancer by 60% (OR:0.4; 95%CI:0.1-0.9). Conversely, seroreactivity to the 89kDa (VacA) protein was significantly higher in gastric cancer patients (OR:2.7; 95%CI:1.0-7.1). There was a highly significant association (p<0.001) between seroreactivity to the 116kDa (CagA) and 89kDa (VacA) proteins, and double positive subjects were found at nearly five fold (OR:4.9; 95%CI:1.0-24.4) enhanced risk of gastric cancer as compared to double negative subjects.

CONCLUSIONS

Seroreactivity to H. pylori low (35kDa) and high (116kDa/89kDa) molecular weight antigens were respectively revealed as protective and risk indicators for gastric cancer.

Gold nanoparticles in biomedical applications: recent advances and perspectives

Gold nanoparticles (GNPs) with controlled geometrical, optical, and surface chemical properties are the subject of intensive studies and applications in biology and medicine. To date, the ever increasing diversity of published examples has included genomics and biosensorics, immunoassays and clinical chemistry, photothermolysis of cancer cells and tumors, targeted delivery of drugs and antigens, and optical bioimaging of cells and tissues with state-of-the-art nanophotonic detection systems. This critical review is focused on the application of GNP conjugates to biomedical diagnostics and analytics, photothermal and photodynamic therapies, and delivery of target molecules. Distinct from other published reviews, we present a summary of the immunological properties of GNPs. For each of the above topics, the basic principles, recent advances, and current challenges are discussed (508 references).

Helicobacter pylori diagnostic tests in children: review of the literature from 1999 to 2009

The array of tests that can be used for diagnosis of Helicobacter pylori infection is large, and it can be confusing to define which test to use particularly in children where results may not be comparable to those obtained in adult patients. Using PubMed, we reviewed the English literature from January 1999 to May 2009 to identify articles that determined sensitivity and specificity of H. pylori invasive and non-invasive diagnostic tests in children. We excluded articles that presented a review of the literature, abstracts, case reports, or series where children's results could not be separated from adult populations. Of the tissue based methods, rapid urease tests have better sensitivity than histology to detect presence of H. pylori; however, histology can detect the pathology associated with disease including gastritis, intestinal metaplasia, and other conditions that could be the cause of the child's symptoms. Culture of gastric tissues or stool has 100% specificity but sensitivity is low. Of the serologic tests, immunoblot has the best sensitivity. The urea breath tests have >75% sensitivity for detection of H. pylori before and after treatment. Immunoassays in stool using monoclonal antibodies have >95% sensitivity for detection of H. pylori before and after treatment. PCR testing can be performed in tissue and stool samples and can detect genes associated to antibiotic resistance. In summary, the current commercial non-invasive tests have adequate sensitivity and specificity for detecting the presence of H. pylori; however, endoscopy with histopathology is the only method that can detect H. pylori and lesions associated with the infection.

Absence of platelet recovery following Helicobacter pylori eradication in childhood chronic idiopathic thrombocytopenic purpura: a multi-center randomized controlled trial

OBJECTIVE

To investigate the effect of Helicobacter pylori eradication on platelet recovery in childhood chronic idiopathic thrombocytopenic purpura (ITP).

PATIENTS AND METHODS

A multi-center randomized controlled trial was conducted. Patients aged 4-18 years, diagnosed with chronic ITP, defined by platelet count below 100 x 10(9)/L lasting more than 6 months without identified causes, were enrolled and underwent (13)C-urea breath test for diagnosis of H. pylori infection. Patients who received prednisolone more than 0.5 mg/kg per day or received other platelet-enhancing therapy were excluded. Patients with H. pylori infection were randomized into two groups: treatment and control groups. Treatment group received a standard protocol for H. pylori eradication and repeated (13)C-UBT at 4-6 weeks to confirm successful therapy while the control group received no specific treatment. Monthly platelet count was monitored for 6 months in both groups. Primary outcome was platelet recovery, defined by platelet count over 100 x 10(9)/L for at least 3 months.

RESULTS

Of the 55 ITP children, 16 (29.1%) had H. pylori infection. There were no differences in age, sex, duration of disease, platelet count, and the dose of prednisolone between the treatment group (n = 7) and control group (n = 9). One patient in control group was withdrawn due to massive gastrointestinal bleeding requiring a high dose prednisolone. At 6 months, platelet recovery was demonstrated in one patient in the treatment group as well as one in the control group.

CONCLUSION

No beneficial effect of H. pylori eradication on platelet recovery in childhood chronic ITP was identified.

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.

Non-invasive diagnosis of H pylori infection: Evaluation of serological tests with and without current infection marker CIM

AIM: To evaluate the performance of commercially available immunochromatographic (ICT) and immunoblot tests covering the current infection marker CIM and conventional ELISA for the diagnosis of H pylori infection in adult dyspeptic patients.

METHODS: Consecutive non-treated dyspeptic patients undergoing diagnostic endoscopy were tested for H pylori infection by culture, rapid urease test, and histology of gastric biopsy specimens. Serum from 61 H pylori infected and 21 non-infected patients were tested for anti-H pylori IgG antibodies by commercial ELISA (AccuBind^TM ELISA, Monobind, USA), ICT (Assure^®H pylori Rapid Test, Genelabs Diagnostics, Singapore), and immunoblot (Helico Blot 2.1, Genelabs Diagnostics, Singapore) assays. ICT and immunoblot kits cover CIM among other parameters and their performance with and without CIM was evaluated separately.

RESULTS: Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of ELISA were 96.7%, 42.8%, 83.1%, 81.8%, and 82.9%, of ICT were 90.1%, 80.9%, 93.2%, 73.9%, and 87.8%, of ICT with CIM were 88.5%, 90.4%, 96.4%, 73.0%, and 89.0%, of immunoblot were 98.3%, 80.9%, 93.7%, 94.4%, and 93.9%, and of immunoblot with CIM were 98.3%, 90.4%, 96.7%, 95.0%, and 96.3%, respectively.

CONCLUSION: Immunoblot with CIM had the best performance. ICT with CIM was found to be more specific and accurate than the conventional ELISA and may be useful for non-invasive diagnosis of H pylori infection.

An evaluation of a serologic test with a current infection marker of Helicobacter pylori before and after eradication therapy in Chinese

BACKGROUND AND AIMS

Development of an accurate and less cumbersome noninvasive method to detect current Helicobacter pylori infection is essential in clinic. The aim of this study was to evaluate the performance of the CIM test, also known as the Assure H. pylori Rapid Test (Genelabs Diagnostics Pty. Ltd., Singapore), for the diagnosis of current H. pylori infection before and after eradication therapy in Chinese population.

METHODS

A total of 452 eligible people were recruited for this study in Jiangsu Province, China. Each individual underwent a 13C urea breath test (13C-UBT). For the evaluation of CIM test after eradication, 115 H. pylori-positive outpatients were treated with 1-week triple therapy. One month after the end of therapy, the patients underwent 13C-UBT again, and the CIM-test was performed 1, 3, and 6 months after the end of therapy. Its performance (sensitivity, specificity, positive and negative predictive values, and accuracy) were determined using the 13C-UBT as a gold standard for H. pylori diagnosis.

RESULTS

H. pylori was detected in 221 (65.6%) of the 337 people by 13C-UBT. The sensitivity, specificity, positive and negative predictive values, and accuracy of the CIM test were 93.2%, 90.5%, 94.9%, 87.5%, and 92.3%, respectively, using 13C-UBT as a gold standard. One month after eradication therapy, the sensitivity, specificity of CIM test were only 50% and 66.7%, 66.7% and 84.6% 3-month after eradication therapy and the sensitivity, specificity increased to 85.7% and 96.9%, respectively, when CIM test was used 6 months after the end of anti-H. pylori therapy.

CONCLUSIONS

The CIM test is a simple, rapid, accurate, cheap, and near-people test. It may be satisfactory for detecting H. pylori infection in cases without eradication therapy, but it could not differentiate the past or current infection correctly within 6 months after anti-H. pylori therapy.

Diagnosis of Helicobacter pylori infection

A growing interest in non-invasive tests for the detection of Helicobacter pylori has been observed recently, reflecting a large number of studies published this year. New tests have been validated, and the old ones have been used in different clinical situations or for different purposes. Stool antigen tests have been extensively evaluated in pre- and post-treatment settings both in adults and children, and the urea breath test has been studied as a predictor of bacterial load, severity of gastric inflammation, and response to eradication treatment. Several studies have also explored the usefulness of some serologic markers as indicators of the gastric mucosa status. With regard to invasive tests, molecular methods are being used more and more, but the breakthrough this year was the direct in vivo observation of H. pylori during endoscopy.