A 13C-urea breath test in children with helicobacter pylori infection: assessment of eradication therapy and follow-up after treatment

Purpose. Our aim was to evaluate the usefulness of the ¹³C-urea breath test (UBT) for the diagnosis of Helicobacter pylori infection, for assessment of the efficacy of eradication therapy, and for post-treatment follow-up in children. Methods. Seventy-two patients who underwent endoscopy for symptoms related to the upper gastrointestinal tract were examined by rapid urease test, histology, and culture. The patients were also studied with serology and UBT. Results. Forty-seven of the 72 patients were diagnosed with H. pylori infection, based on the results of biopsy-based tests and serology. As an initial diagnostic test to detect H. pylori infection, the sensitivity of the UBT was 95%, which was comparable with that of histology (94%), rapid urease test (96%), and serology (91%) and was greater than that of culture (79%). The specificity of the UBT was 100%, which was comparable with that of the other four tests. The efficacy of eradication therapy was assessed by biopsy-based tests and the UBT in 24 H. pylori-positive patients. For this purpose, the sensitivities of UBT and histology were 100%, while the sensitivities of culture and the rapid urease test were 88%. The specificity was 100% for all of these tests. Eleven patients were assessed by biopsy-based tests and UBT after more than 6 months of post-treatment follow-up. There were no discordances between the results of the UBT and those of the biopsy-based tests in any of the patients. Conclusions. The UBT may be useful for detecting H. pylori infection in children with upper gastrointestinal tract symptoms, for assessment of the efficacy of eradication therapy, and for the follow-up evaluation of patients after the therapy. Received: November 24, 2000 / Accepted: March 30, 2001     

Accuracy of a monoclonal antibody-based stool antigen test in the diagnosis of Helicobacter pylori infection

Background: Recent availability of tests for Helicobacter pylori antigens in stool samples has provided potentially useful tools for epidemiological studies and clinical settings. The aim of this study was to evaluate a monoclonal antibody-based H. pylori antigen stool test in the primary diagnosis of H. pylori infection, and to study the test performance after patients were treated with lanzoprazole, and after eradication therapy. Methods: The study included 122 dyspeptic patients. At gastroscopy, biopsy specimens were obtained for culture and histology. Stool antigen and [[Formula: See Text]C]-urea breath tests were performed concurrently. Positive culture alone or a positive [[Formula: See Text]C]-urea breath test in combination with positive histology defined the reference standard. Forty-three Hp +ve patients were treated with lanzoprazole for 2 to 4 weeks, and stool antigen tests were performed on days 1 and 7 post-treatment. After eradication therapy, 32 patients were re-examined for H. pylori infection. Results: Prevalence of H. pylori was 44.3%. Sensitivity and specificity for the stool antigen test in the primary diagnosis of H. pylori infection were 98% and 94%, with positive and negative likelihood ratios of 16.7 and 0.02, respectively. All patients had positive stool tests immediately after lanzoprazole treatment, whereas 2 patients had negative stool tests after 7 days. Triple therapy rendered all patients stool test negative. Conclusions: The monoclonal antibody-based stool antigen test is an accurate tool in the primary diagnosis of H. pylori infection and after eradication therapy. Lanzoprazole treatment does not influence the clinical performance of the test.     

Comparison of a monoclonal with a polyclonal antibody-based enzyme immunoassay stool test in diagnosing Helicobacter pylori infection after eradication therapy

Background  Recently, a novel Helicobacter pylori stool antigen test (Testmate pylori antigen EIA) using monoclonal antibodies against H. pylori catalase has been developed commercially. This study assessed the diagnostic usefulness of the stool antigen test compared with a polyclonal enzyme immunoassay (HpSA test) after H. pylori eradication. Methods  A total of 150 patients with H. pylori infection were treated by triple therapy with PPI and amoxicillin with either clarithromycin or metronidazole. H. pylori stool antigen was tested 4 and 8 weeks after eradication. The outcome of H. pylori eradication was assessed by urea breath test (UBT) 8 weeks after the end of therapy. Discordant results were followed by endoscopic examination. Results  Of 150 patients enrolled, H. pylori status was negative in 122 cases and positive in 28 cases, assessed by the ¹³C-UBT. On the other hand, the monoclonal stool antigen test results were negative in 126 cases and positive in 24. The polyclonal stool test results were negative in 126 cases and positive in 22. The overall sensitivity and specificity of the monoclonal stool antigen test were 91.6% (95% CI 85.9–97.3%) and 98.4% (95% CI 97.3–99.5%). The overall sensitivity and specificity of the polyclonal stool antigen test were 87.0% (95% CI 86.9–94.0%) and 97.5% (95% CI 96.1–98.9%). Conclusion  The new stool antigen test using monoclonal antibody is useful for the diagnosis of H. pylori eradication 4 weeks after the end of treatment.     

Evaluation of a rapid stoolantigen test for the diagnosis of Helicobacter pylori infection in Chinese patients

OBJECTIVE: To evaluate the accuracy of a rapid assay that wasdeveloped to detect Helicobacter pylori antigen in the stool,using the principle of immunochromatography, in the Chinese population. METHODS: Eligible patients without prior treatment of H.pylori were recruited. An in‐house rapid urease test (RUT) andhistology were used as the gold standard. The results of the rapidstool antigen test were compared with the gold standard. RESULTS: Valid rapid stool antigen test results for interpretationwere obtained from 94 consecutive patients (mean age: 52.5, range:22?82 years). Sensitivity, specificity, positive predictivevalue, negative predictive value and accuracy were, respectively, 77.5%,87.0%, 81.6%, 83.9% and 83.0%.The test was easy to perform and results were available within 15 min. CONCLUSION: The rapid stool antigen test using immunochromatography accuratelydiagnoses H. pylori infection in Chinese patients.     

Clinical significance of oral urease in diagnosis of Helicobacter pylori infection by [13C]urea breath test

This study was performed to evaluate the effect of oral flora on [¹³C]urea breath test in detecting H. pylori infection and find an optimal method and timing for sample collection. Forty-five volunteers were included in this study. The [¹³C]urea breath test was performed using mouthwash, endoscopic administration, and conventional methods. According to the receiver-operating characteristic curves, the earliest optimal time for discriminating H. pylori-positive and H. pylori-negative patients was at 25 min with the mouthwash method with 78% sensitivity and 82% specificity, at 2 min with the endoscopic administration method with 100% sensitivity and 100% specificity, and at 6 min with the conventional method with 100% sensitivity and 95% specificity. The study shows a significant effect of oral urease on the results of the [¹³C]urea breath test. The timing of sampling collection can be shortened to 6 min with the conventional method or to 2 min through endoscopic administration.     

Helicobacter pylori stool antigen (HpSA) test--a simple, accurate and non-invasive test for detection of Helicobacter pylori infection

BACKGROUND/AIMS: To access the reliability of a newly developed test, the Helicobacter pylori (H. pylori) stool antigen (HpSA) test was used for detection of H. pylori infection. METHODOLOGY: Stool specimens were collected from 33 consecutive patients (19 males and 14 females, age range: 16-73 years, mean: 49 years) who received upper gastrointestinal endoscopic examination for gastrointestinal symptoms. The H. pylori status was evaluated based on six different tests: culture, histology, biopsy urease test, 13C-urea breath test (13C-UBT), serology, and HpSA test. A commercial kit using an enzyme-linked immunosorbent assay examined HpSA in the stool. H. pylori status was defined as positive when the culture was positive or concordance of three of the other four tests (histology, biopsy urease test, 13C-UBT, and serology) was positive. RESULTS: Twenty patients were diagnosed as H. pylori-positive. The HpSA test was positive in 19 patients and negative in 14 patients. The sensitivity and specificity were 95.0% and 100%, respectively. The overall accuracy rate was 96.3%. CONCLUSIONS: The HpSA test is a new, simple, non-invasive method for accurate diagnosis of H. pylori infection.     

Studies of 13C-urea breath test for diagnosis of Helicobacter pylori infection in Japan

In recent years Helicobacter pylori infection has been implicated in the etiology of a variety of upper gastrointestinal diseases. The aim of this multi-center trial was to search for the cut-off value of the simple ¹³C-urea breath test (¹³C-UBT) for diagnosis of H. pylori infection, and to examine the sensitivity and specificity of ¹³C-UBT for culture, the rapid urease test (CLO test), histology, and serological tests. Two hundred and forty-eight patients participated in this study after giving their informed consent. Endoscopic biopsy specimens were taken from gastric antrum and corpus for culture (190 patients), CLO test (222 patients), and histology (98 patients). A serological test was carried out for all patients. H. pylori infection was established when culture was positive or more than two of the tests, histology, CLO test, and serological test, were positive, and non-infection status was established when the all tests more than two tests were negative. After baseline breath samples were taken, the patients (who had fasted) were given 100 mg of ¹³C-urea in 100 ml water while sitting; they washed out the mouth with water. They were then placed in the left lateral decubitus position for 5 min, and additional breath samples were taken 10, 20, 30, 45, and 60 min after urea administration, with patients in the sitting position. One hundred and sixty-five of the 248 patients were infected, 48 were not infected, and H. pylori infection status was not evaluated in 35 by endoscopic and serological tests. Breath samples at 20 min were employed to determine the cut-off value. Using the receiver operating characteristic (ROC) curve, we determined the cut-off value for a positive UBT at 2.5 Δ‰. The sensitivities of UBT for culture, CLO test, histology, and serological test were 98.4%, 98.6%, 100.0%, and 92.5%, and the specificities were 78.8%, 82.5%, 83.3%, and 87.3%, respectively. The cut-off value of 13C-UBT for the diagnosis of H. pylori infection was 2.5 Δ‰; this test is a simple and non-invasive method for the diagnosis of this infection and has high sensitivity and specificity. Received Nov. 18, 1996; accepted June 20, 1997     

Comparison between a new 13C-urea breath test, using a film-coated tablet, and the conventional 13C-urea breath test for the detection of Helicobacter pylori infection

Background In Japan, urea breath-testing includes mouth rinsing with water immediately after the ingestion of ¹³C-urea solution, to prevent false-positive results that are caused by oral bacteria with urease activity. Our objective was to evaluate the diagnostic performance of a urea breath test using a film-coated ¹³C-urea tablet and omitting mouth rinsing.Methods The study was a multicenter trial comparing the solution- and tablet-based urea breath tests (UBTs). Helicobacter pylori status was determined by histology, culture, and rapid urease testing.Results Of the 255 subjects who completed the study, evaluation of the tablet-based UBT was possible in 254, and comparison of the tablet-based UBT and the solution-based UBT was possible in 250 patients. When the assessment achieved by a combination of biopsy-based methods was used as a reference standard, the sensitivity, specificity, and accuracy of the tablet-based method were determined to be 97.7%, 98.4%, and 98.0%, respectively. When the results of the solution-based UBT were used as a reference standard, the sensitivity, specificity, and accuracy of the tablet-based UBT were determined to be 96.9%, 97.6%, and 97.2%, respectively.Conclusions The ¹³C-urea tablet-based method proved to be a simple and accurate test for the diagnosis of H. Pylori infection. Mouth rinsing was not required.     

Helicobacter Pylori and Precancerous Gastric Lesions

Background: To determine the relationship between Helicobacter pylori (H. pylori) infection and the precancerous gastric lesions: atrophic gastritis (AG) and intestinal metaplasia (IM) and dysplasia. Methods: A total of 347 dyspeptic patients, including 141 H. pylori‐positive patients and 206 H. pylori‐negative patients, were studied alongside age‐ and sex‐matched controls. The patients underwent gastroscopy and endoscopic biopsy for detection of H. pylori, and histological examinations. Helicobacter pylori was detected by a urease test (CLO; Delta West; Bentley, Australia), by histology (H&E stain, Giemsa) and by serology (BioSig; BioMeditech, NJ, USA). Atrophic gastritis, IM and dysplasia were detected by histological examination (Giemsa, H&E stain). Results: There is a higher rate of atrophic gastritis in H. pylori‐positive than in H. pylori‐negative patients (46 vs 13.5%, odds ratio (OR) = 5.4; P < 0.01). Gastritis in H. pylori‐positive patients also has a higher rate of activity than in H. pylori‐negative patients. The rate of IM is higher in H. pylori‐positive patients than in H. pylori‐negative patients (35 vs 11%; OR = 4.3; P < 0.01). Metaplasia is more often diffuse in H. pylori‐positive than in H. pylori‐negative patients. Dysplasia is more common in H. pylori‐positive than in H. pylori‐negative patients (12 and 3.8%; OR = 3.3; P < 0.01). Conclusions: This study supports the suggestion of a relationship between H. pylori infection and precancerous gastric lesions. Wherever H. pylori is present, the precancerous lesions are more common and more severe.     

Evaluation of a new immunochromatographic test for Helicobacter pylori IgG antibodies in elderly symptomatic patients

Aim: To determine the diagnostic value of a new serum and whole blood serological IgG antibody test, FlexPack HP, for the diagnosis of Helicobacter pylori in elderly symptomatic patients. Methods: 94 consecutive symptomatic patients who underwent upper endoscopy were studied (mean age, 62.6 years). On endoscopy, the presence of H. pylori infection was examined by biopsies from gastric antrum and body for rapid urease test and histologic examination. Blood was drawn prior to endoscopy and both blood and serum were immediately analyzed for human IgG antibodies to H. pylori by a new commercially available qualitative immunochromatographic method, FlexPack HP. This test incorporates high-molecular weight cell-associated proteins (HM-CAP), which are highly specific for H. pylori IgG antibodies. Results: Overall agreement for FlexPack HP whole blood vs FlexPack HP serum was 100%, and agreement with biopsy results was 71%. The gold standard (detection of H. pylori by histology or urease test) identified H. pylori in 61 patients (65%). Complete agreement was observed between the gold standard test and the serology kit in 72% (68/94) of sera (51 positive and 17 negative). Disagreement was found in sera of 26 patients; 16 sera were negative by the gold standard and positive by FlexPack HP and 10 patients were found negative by serology. The sensitivity of FlexPack HP was 84% and the specificity 52% when compared with the gold standard. Conclusions: FlexPack HP serum and whole blood test is a simple and reliable method for the detection of H. pylori antibodies, with 100% agreement between the serum and blood results. In the elderly symptomatic patients the sensitivity of FlexPack HP was similar to that of other serologic tests, but the specificity was relatively low, limiting its use in this population. (Received Jan. 7, 1998; accepted Aug. 28, 1998)     

Influence of urease activity in the intestinal tract on the results of 13C-urea breath test

Background and Aim: A late rise in ¹³CO2 excretion in the ¹³C‐urea breath test (UBT) should be found when the substrate passes rapidly through the stomach and makes contact with the colonic bacteria. The aim of this study was to evaluate the influence of intestinal urease activity on the results of the UBT. Method: A total of 143 subjects who were diagnosed as Helicobacter pylori negative by serology, histology and rapid urease test were recruited. At the end of endoscopy, the tip of the endoscope was placed to the second part of the duodenum and 20 mL of water containing 100 mg of ¹³C‐urea was sprayed into the duodenum. Breath samples were taken at baseline and at 5, 10, 20, 30 and 60 min after administration. Results: Of 143 subjects, breath Δ¹³CO2 values higher than 2.5‰ were detected in six (4.2%), four (2.8%) and five (3.5%) subjects at 20, 30 and 60 min, respectively. There was no subject with high Δ¹³CO2 values at 5 and 10 min. Only one subject had an immediate rise at 60 min. Conclusion: Variability derived from urease activity in the intestinal tract appears to be minimal up to 60 min after ingestion of the test urea.     

Accuracy of Seven Different Tests for the Diagnosis of Helicobacter pylori Infection and the Impact of H2-Receptor Antagonists on Test Results

Background: In this study we compared the accuracy of seven diagnostic tests in diagnosing Helicobacter pylori infection. Methods: Over 1 year 351 consecutive dyspeptic patients were tested for H. pylori infection by means of antral biopsy specimens for the rapid urease test (RUT), culture, microscopy (acridine stain), and the laboratory urease test (LUT) and, in addition, with ¹⁴C urea breath test (UBT), IgG serology, and IgA serology (Orion Diagnostica Pyloriset New EIA-G and New EIA-A). The criterion for H. pylori infection was a minimum of three positive tests. Before being tested, 38% of the patients had used an H₂-receptor antagonist (H₂RA). Results: Two-hundred and twenty-four patients (64%) were H. pylori-positive. The sensitivity and specificity of the tests were as follows (percentages): RUT, 85, 99; culture, 93, 100; microscopy, 81, 98; LUT, 80, 100; UBT, 95, 95; IgG serology, 99, 91; and IgA serology, 88, 91. The accuracy of the RUT and LUT was reduced in patients receiving HRA therapy (P = 0.04 and 0.01, respectively). Conclusions: Culture, UBT, and IgG serology were all superior to the other four tests in diagnosing H. pylori infection. Invasive urease-based tests were less accurate in patients receiving HRAs.     

CAN DENTAL TREATMENT BE THE INFECTION ROUTE OF H. PYLORI TRANSMISSION IN ADULTS? THREE CASES OF ACUTE GASTRIC MUCOSAL LESIONS AFTER DENTAL TREATMENT

Acute gastric mucosal lesions (AGML) comprise a typical clinical entity in patients with acute gastritis, which is characterized by severe erosion, hemorrhage, and ulceration. It is thought that most Helicobacter pylori (H. pylori) infections are established during childhood through human‐to‐human contact. Initial H. pylori infection in an adult is rare, and the transmission route is unknown. The first patient was a 27‐year‐old woman whose chief complaint was epigastric pain. She underwent dental treatment for 30 min and developed sudden epigastric pain 6 h after the treatment. Endoscopic examination revealed multiple hemorrhagic erosions in the antrum. Rapid urease test and histology for H. pylori were positive, but serum anti‐H. pylori IgG antibody was negative at the onset. Serology and urea breath test were positive for H. pylori 2 months after the dental treatment. The second and third patients were diagnosed as having AGML 2 and 4 days after dental treatment, respectively. Culture for H. pylori was positive and serology was negative at the onset, but serology showed seroconversion 2 months after the dental treatment in both patients. These findings indicate that dental treatment is a possible route for H. pylori infection in patients with AGML.     

Helicobacter pylori

Helicobacter pylori is associated with various gastroduodenal diseases such as peptic ulcer, functional dyspepsia, MALT lymphoma and distal gastric cancer. Diagnosis of H. pylori can be established by non-invasive (^13Curea breath test, stool antigen test, serology) and invasive (histology, rapid urease test, culture) tests. In adults, culture and susceptibility testing should or must be performed after failing of first-line therapy in case of a control endoscopy and before third-line therapy, respectively. Peptic ulcer and gastric MALT lymphoma represent obligatory indications for eradication therapy. Other potential indications are functional dyspepsia, prevention of gastric cancer in individuals being at risk, and before starting treatment with traditional non-steroid antiphlogistics. First-line therapy is performed with a 7-days combination of proton pump inhibitor with clarithromycin and amoxicillin or metronidazole. In second-line therapy levofloxacin and rifabutin are good rescue antibiotics.     

Usefulness of the Immunological Rapid Urease Test for Detection of Helicobacter pylori in Patients Who are Reluctant to Undergo Endoscopic Biopsies

Cardiovascular diseases and liver cirrhosis are in the list of Helicobacter pylori-related extragastric diseases. Patients with cirrhosis and cardiovascular diseases under the control of aspirin have increased risk of gastrointestinal bleeding. The immunological rapid urease test (IRUT) provides a rapid and safe diagnostic test for H. pylori using gastric mucus collected at endoscopy. We investigated its usefulness in 93 patients with these extragastric diseases including 46 with H. pylori infection assessed by urea breath test and serology. Twenty H. pylori-infected patients received eradication therapy and the IRUT was assessed to evaluate the efficacy of bacterial eradication. The sensitivity, specificity, and positive and negative predictive values for IRUT were 96%, 90%, 90%, and 96%, respectively. The results of IRUT completely agreed with those of urea breath test following anti-H. pylori therapy. The IRUT has acceptable diagnostic performance in such cohorts reluctant to undergo endoscopic biopsies due to the risk of bleeding.     

Endoscopic 13C‐urea breath test

Background : Several modifications of the ¹³C‐urea breath test (UBT) for the diagnosis of Helicobacter pylori infection have been published. A new modification of UBT is described with the aim of avoiding the influence of urease activities from the commensal organisms other than H. pylori upon ¹³CO₂ excretion in the breath. Methods : The new modified UBT was performed in 295 consecutive patients undergoing esophagogastroscopy. After the collection of a baseline breath sample, an endoscopy was carried out. A baseline gastric gas sample was collected through a biopsy channel, and 20 mL of sterile water containing 100 mg of ¹³C‐urea was sprayed onto the gastric mucosa. The scope was drawn after spraying the ¹³C‐urea solution and collecting a gastric gas sample. Breath samples were collected 5, 10, 20 and 30 min after the spraying of ¹³C‐urea. Results : The mean ± SD value of gastric gas samples for excess δ ¹³ CO₂ in H. pylori‐positive patients was 1036.7 ± 1309.0‰, and 6.0 ± 23.3‰ in H. pylori‐negative patients. The cut‐off point as determined by receiver operator characteristic (ROC) curves for the gastric gas samples was 10‰. The sensitivity and specificity for this new method were 95.4% and 92.5%, respectively. Conclusion : The method of endoscopically collecting ¹³CO₂ gas in the stomach, which is not affected by the metabolism or by the absorption of ¹³C, provides an accurate and sensitive means for the detection of H. pylori.     

Comparison between the <Superscript>13</Superscript>C-urea breath test and stool antigen test for the diagnosis of childhood <Emphasis Type="Italic">Helicobacter pylori</Emphasis> infection

Background As noninvasive tests for Helicobacter pylori infection, the ¹³C-urea breath test (UBT) and stool antigen test have been widely used. In children, however, there are few studies reporting which test shows superior performance. The purpose of this study was to compare the ¹³C-UBT and stool antigen test for their accuracy in diagnosing H. pylori infection in children.Methods A total of 123 Japanese children, ages 2 to 17 years (mean, 12 years) who underwent gastric biopsies for H. pylori infection were studied. The diagnoses included gastritis (n = 55), gastric ulcer (n = 5), duodenal ulcer (n = 20), iron-deficiency anemia (n = 7), and other conditions (n = 36). The cutoff value of the ¹³C-UBT was defined to be 3.5. The stool antigen test was performed using the HpSA enzyme-linked immunosorbent assay (ELISA) (Premier Platinum HpSA). In 16 patients who received eradication therapy, the ¹³C-UBT and HpSA were repeated 2 months after treatment.Results Based on biopsy tests, 60 children were infected with H. pylori and 63 children were not. For the ¹³C-UBT, the sensitivity, specificity, and accuracy were 95.0% (95% confidence interval [CI], 86.1%–99.0%), 98.4% (95% CI, 91.5%–100%), and 96.4% (95% CI, 93.6%–99.9%), respectively. For the HpSA, the sensitivity, specificity, and accuracy were 98.3% (95% CI, 90.8%–100%), 98.4% (95% CI, 91.2%–100%), and 98.3% (95% CI, 96.0%–100%), respectively. There were no significant differences between the performance of these two tests. In the assessment of H. pylori eradication, the results of ¹³C-UBT and HpSA agreed with those of biopsy tests.Conclusions The ¹³C-UBT and the HpSA are equally accurate for the diagnosis of active H. pylori infection in Japanese children.Kazuie Iinuma, for the Japanese Pediatric Helicobacter study Group     

Comparison of two new rapid serology tests for diagnois of Helicobacter pylori infection in Chinese patients

Background. Rapid serology test is a simple and convenient way for diagnosing Helicobacter pylori infection. However, performances of these tests are usually less satisfactory than expected, particularly in developing countries.Aim. To evaluate the performances of two newly developed rapid serology tests for Helicobacter pylori infection.Patients. Consecutive Chinese dyspeptic patients undergoing upper gastrointestinal endoscopy.Methods. Gastric biopsies were obtained from antrum and corpus for rapid urease test and histological examination. Diagnosis of Helicobacter pylori infection was based on two or more positive results in rapid urease test, histology and [¹³C] urea breath test. Patients' sera were tested against two rapid serology tests: ASSURE Hp Rapid Test (Genelabs Diagnostics, Singapore) and SureStep (Applied Biotech, San Diego, CA, USA).Results. A total of 148 patients were evaluated and Helicobacter pylori infection was diagnosed in 78 (53%) patients by gold standard. The sensitivities of ASSURE Hp and SureStep were, respectively, 94% and 71 % (p=0.0003). Specificities of the two test kits were both 90%. The overall accuracy of ASSURE Hp was significantly higher than SureStep (92% versus 80%, P=0.004).Conclusion: Both rapid serology tests appear to be specific in diagnosing Helicobacter pylori infection in the Chinese populations. However, the ASSURE Hp test is more sensitive and accurate than the SureStep test.     

A better method for confirming <Emphasis Type="Italic">Helicobacter pylori</Emphasis> infection in Mongolian gerbils

Background. Our aim was to evaluate the accuracy of the stool antigen test and the optimal time point for detecting Helicobacter pylori infection in a Mongolian gerbil model. Methods. We inoculated 8-week-old Mongolian gerbils with H. pylori (Vac A (+)/CagA(+)). The gerbil-infected model was developed as follows: H. pylori was put into broth (about 10⁹ CFU/ml), and 50 gerbils were then fed with 1 ml intragastrically twice within a 3-day interval. Another ten gerbils were fed broth only. Twenty-six weeks after the inoculation, the gerbils were killed. The gastric mucosa was sampled for a series of examinations including culture, histology, rapid urease test, and polymerase chain reaction. Stool samples for a stool antigen test, H. pylori-specific stool antigen assay (HpSA), were collected during weeks 4, 6, 8, 12, and 26 after inoculation. Of the 50 gerbils inoculated with H. pylori, the inoculation was successful in 88%. Severe active gastritis, ulceration, and intestinal metaplasia were obvious. Results. The HpSA test results were sensitivity, 88.6%; specificity, 100%; positive predictive value (PPV), 100%; negative predictive value (NPV), 54.5%, and accuracy, 90%. The HpSA test began to be more sensitive and accurate (P < 0.05) beginning during week 6 after inoculation. We also found that H. pylori could be detected earlier and more easily in the group with high H. pylori density. Conclusions. HpSA seems to be suitable for confirming colonization of gerbils with H. pylori. The optimal testing time point is around 6 weeks after inoculation. This test is a good choice for long-term observation of H. pylori infection in Mongolian gerbils.     

Comparison of stool immunoassay with standard methods for detection of Helicobacter pylori infection in patients with upper-gastrointestinal bleeding of peptic origin

OBJECTIVE: To assess the accuracy of the determination of Helicobacter pylori infection by a stool immunoassay in patients with upper-gastrointestinal bleeding (UGB) of peptic origin, in comparison with the routine histological study, serology, rapid urease and 13C-breath tests. METHODS: Sixty-eight patients with endoscopically proven UGB of peptic origin were included. The presence of H. pylori was considered when observed on histology or, if negative, by the positive indications of two of the remaining tests (serology, rapid urease,13C-breath test). The accuracy of stool immunoassay was estimated according to results obtained with other diagnostic methods. RESULTS: Lesions causing gastrointestinal bleeding were 49 duodenal ulcers, 11 gastric ulcers, six pyloric channel ulcers, 13 acute lesions of the gastric mucosa, and 16 erosive duodenitis. H. pylori infection was present in 59 (86.76%) patients. Forty-one patients had received nonsteroidal anti-inflammatory drugs. The sensitivity and specificity of the diagnostic methods were 47.5% and 100% for the rapid urease test, 93% and 87.5% for the breath test, 86.4% and 77.7% for serology, 89.4% and 100% for histology, and 96.6% and 33.3% for the stool test. CONCLUSIONS: The detection of H. pylori antigen in stools in patients with UGB of peptic origin has a good sensitivity (96.6%) but a low specificity (33.3%) for the diagnosis of H. pylori infection, which probably makes this test an inadequate tool in this setting if utilized alone.