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.     

Long‐term infection with Helicobacter pylori in Mongolian gerbils

Objective: To investigate pathological changes occurring in the stomach of the Mongolian gerbil during long‐term Helicobacter pylori infection. Methods: Four‐week‐old male Mongolian gerbils were used, which were free from specific pathogens. Eighty Mongolian gerbils were inoculated orally with a suspension of H. pylori NCTC 11637 (0.5 mL, 2 × 10¹⁰ CFU/L) in a Brucella broth. To act as controls, a further 30 gerbils were fed with a Brucella broth only. Infected gerbils were killed 10, 25, 45, 55 and 65 weeks after infection. Control gerbils were killed at 10, 45 and 65 weeks. The stomach of each gerbil was removed and opened. Stomach samples for histological examination were fixed in neutral buffered formalin, embedded in paraffin, sectioned and stained with hematoxylin and eosin for analyzing histological changes, Giemsa stain for detecting H. pylori and Alcian blue (AB)/periodic acid?Schiff stain for examining intestinal metaplasia. Results: The Mongolian gerbil model for studying long‐term H. pylori infection was successfully established. Helicobacter pylori induced a progression from normal gastric mucosa to chronic gastritis, glandular atrophy, intestinal metaplasia and dysplasia, although no adenocarcinomas were found in the experimental animals. Conclusions: Helicobacter pylori NCTC 11637 is able to easily colonize the glandular stomach mucosa of the Mongolian gerbil. This model is stable, and the histological changes observed in the stomach are similar to those that occur in humans with H. pylori infection.     

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     

Utility and limitations of a method for detecting Helicobacter pylori-specific antigens in the stool

Background: Recently, a method for detecting Helicobacter pylori-specific antigens in the stool (HpSA) has been proposed to be useful clinically. The aim of this study was to determine the accuracy of HpSA for the diagnosis of H. pylori infection, including early assessment after eradication treatment, and the potential for quantitative evaluation of H. pylori in the stomach. Methods: The subjects were 85 patients with gastroduodenal disorders who underwent endoscopic examination. Of these, 36 were treated for eradication of H. pylori infection and reassessed 4–8 weeks after treatment. HpSA was tested by enzyme immunoassay. For the definitive diagnosis of H. pylori infection, biopsy specimens were taken endoscopically and examined by quantitative culture, rapid urease test, and immunohistostaining. In addition, serum antibody against H. pylori was tested before the eradication treatment and a ¹³C-urea breath test was conducted after treatment. The results of these reference tests were compared with those obtained by HpSA. Results: The sensitivity and specificity of HpSA were 90.4% and 100% before eradication treatment and 57.1% and 100% after the treatment. There was a positive correlation between the optical density of HpSA and the number of H. pylori bacilli evaluated by quantitative culture. Conclusions: The HpSA test is considered to be an accurate method for the diagnosis of H. pylori infection, with high specificity. However, there may be problems of false negativity if HpSA is used for the early assessment of treatment efficacy. Furthermore, HpSA is suggested to have potential for the quantitative evaluation of H. pylori status in the stomach. Received: March 29, 2002 / Accepted: August 30, 2002 Reprint requests to: Y. Noda, Present address: Department of Internal Medicine, Toyama Prefectural Central Hospital, 2-2-78 Nishinagae, Toyama 930-8550, Japan     

Evaluation of combined antibiotic-omeprazole therapies in Helicobacter pylori-infected Mongolian gerbils

Mongolian gerbils are a laboratory host for gastric colonization with Helicobacter pylori, showing gastritis followed by typical gastric ulcer after infection with H. pylori. In such gerbils, we evaluated combined therapies of amoxicillin (AMPC) and clarithromycin (CAM) as antibiotics, and omeprazole (OPZ) as a H⁺/K⁺ adenosine triphosphatase (ATPase) inhibitor. The gerbils were orally inoculated with 2 × 10⁸ bacilli of ^{H. pylori} ATCC 43504. Four weeks after inoculation, the infected gerbils were orally treated singly with OPZ, AMPC, and CAM, and their insufficient efficacy on bacterial clearance was confirmed by a polymerase chain reaction technique, and by a culture method. In contrast, combined therapy of OPZ plus either AMPC or CAM showed significant bacterial clearance, demonstrating the efficacy of this combined therapy in the gerbil model. Mongolian gerbils are suggested to be useful for the pharmacological evaluation of anti-H. pylori compounds. Received Mar. 11, 1997; accepted June 27, 1997     

Development of poorly differentiated adenocarcinoma and carcinoid due to long-term Helicobacter pylori colonization in Mongolian gerbils

A Mongolian gerbil model was used to clarify whether long-term colonization by Helicobacter pylori is an important risk factor for the development of gastric cancer. Fifty-nine gerbils (3 controls and 56 gerbils inoculated with H. pylori) were killed at various times (average, 23 months) more than 12 months after H. pylori inoculation. In the H. pylori-inoculated group, poorly differentiated adenocarcinoma was observed in the pylorus of 1 gerbil, and carcinoid was observed in the fundus of the stomach in 18 gerbils. No lesions were found in the stomachs of the 3 control gerbils. The results imply that long-term colonization by H. pylori is an important risk factor for the development of gastric adenocarcinoma and carcinoid. Received: September 9, 1998 / Accepted: March 26, 1999     

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.     

Paradoxical Role of Helicobacter pylori Infection: Protective Effect Against Ethanol-Induced Gastric Mucosal Injury in Mongolian Gerbils

We investigated the effect of ethanol (a representative necrotizing agent) on gastritis induced by Helicobacter pylori infection in Mongolian gerbils. Seventy-eight gerbils were used. Four and 12 weeks after H. pylori inoculation, 30% ethanol was administered into the stomach. The stomachs were removed after 30 min, the intramucosal prostaglandin (PG) E₂ concentration was measured, and histopathology was recorded. H. pylori infection caused chronic active gastritis, gastric erosion, hypersecretion of mucin from gland mucus cells, and a rise in the activity of intramucosal PGE₂. After ethanol administration, gastric erosion was significantly less in animals infected with H. pylori than in uninfected animals. In conclusion, in the early stage of H. pylori infection, accentuation of intramucosal PGE₂ and hypersecretion of mucin from gland mucus cells have a protective effect against gastric mucosal injury induced by necrotizing agents.     

Accuracy of Stool Antigen Test in Posteradication Assessment of Helicobacter pylori Infection

Our aim was to evaluate the accuracy of HpSA test in the diagnosis of Helicobacter pylori infection after the end of eradication therapy. In all 106 H. pylori-positive patients (55 men and 51 women, mean age 51 years, range 19–82) were treated with a course of eradicating regimen. [¹³C]Urea breath test (UBT) and HpSA were performed four weeks after stopping the treatment. The diagnostic accuracy of HpSA was evaluated in comparison with the results of [¹³C]UBT. In 90 patients (85%) H. pylori was eradicated according to [¹³C]urea breath test. After eradication, sensitivity of HpSA was 87.5%, specificity 95.5%, positive predictive value 77.8%, negative predictive value 97.7%, and diagnostic accuracy 94.3%. HpSA is a valuable test in the posteradication assessment of H. pylori infection.     

Attenuated Apoptosis in H. pylori-Colonized Gastric Mucosa of Mongolian Gerbils in Comparison with Mice

Although gastric cancer formation with H. pylori in Mongolian gerbils was recently reported, the same inoculation procedure did not result in cancer formation in other animals such as mice. Disturbed regulation of apoptosis and cell proliferation are known to link the multistep process of carcinogenesis. The present study is designed to examine the level of gastric epithelial cell apoptosis in Mongolian gerbils colonized with the H. pylori (Sydney strain: SS1) in comparison with that in mice. Mice (C57BL/6) and Mongolian gerbils were orally inoculated with SS1 and the stomachs were examined 9 and 18 months later. MPO activity increased persistently in gerbils, but increased transiently in mice. While the levels of DNA fragmentation, caspase-3 activity, and the number of TUNEL-positive cells increased significantly in mice, such parameters were attenuated in gerbils. On the other hand, the number of PCNA-positive cells increased after SS1 inoculation only in Mongolian gerbils, suggesting the enhancement of cell turnover in H. pylori-colonized gerbils. In conclusion, the SS1-induced increase in gastric mucosal apoptosis observed in mice was attenuated significantly in Mongolian gerbils, suggesting the causative role for the higher incidence of gastric carcinogenesis in this animal.     

[14C]Urea Breath Test Is Not Sensitive for Detection of Acute Helicobacter pylori Infection in Rhesus Monkeys (Macaca mulatta)

The urea breath test is sensitive and specific for detection of chronic infection with H. pylori. We sought to determine the sensitivity of the [¹⁴C]urea breath test for detection of acute H. pylori infection using experimentally infected rhesus monkeys. Eighteen monkeys were inoculated with H. pylori. Serial [¹⁴C]urea breath tests and cultures of gastric biopsies were performed before and up to 10 weeks after inoculation. Cultures from all 18 monkeys were positive for H. pylori at each time point. The sensitivity of the [¹⁴C]urea breath test increased systematically from 43% at two weeks after inoculation up to 93% at 10 weeks after inoculation. Quantitative cultures of H. pylori showed a tendency to decline over time following inoculation. We conclude that the [¹⁴C]urea breath test is not sensitive for detection of acute H. pylori infection in rhesus monkeys until 10 weeks after inoculation. While this may reflect a gradual increase in bacterial load that was not detected by limited sampling, our data are not consistent with this hypothesis.     

Role of Cholecystokinin in Relaxation of the Proximal Stomach

Background: Helicobacter pylori is a human gastric carcinogen. Sterigmatocystin (ST), a fungus toxin, is a risk factor of gastric cancer. Cytotoxin-vacuolation toxin A (VacA) present in supernatants of H. pylori suspensions can cause gastritis and ulcer. The aim of this study was to examine the effects of H. pylori, ST and VacA in Mongolian gerbils. Methods: Male Mongolian gerbils (n = 196) were treated with H. pylori supernatants (10 ml/1000 mg) mixed with diet or inoculated intragastrically with H. pylori alone or with ST (100 or 1000 ppb), and then killed 27 months later. Gastric tissue sections were stained with haematoxylin and eosin (H&;E), periodic acid-Schiff (PAS), Alcian blue (AB, pH 2.5) and with immunostaining for PCNA and p53 expression. Results: In H. pylori-infected gerbils, the normal mucosa was replaced by hyperplastic epithelium. Severe gastritis, cystic dilatation of gastric glands, hyperplastic polyps and intestinal metaplasia were observed. In H. pylori + ST (1000 ppb) gerbils, intestinal metaplasia was significantly more frequent than in H. pylori alone animals. No pathological changes were observed in the H. pylori supernatant group. Osseous metaplasia was observed in the H. pylori + ST (100 ppb) group. Serum gastrin levels of the H. pylori + ST (1000 ppb) group were significantly higher than those of the other groups. PCNA labelling index and p53 index of infected gerbils were significantly higher than those of uninfected groups. Conclusion: H. pylori causes gastritis, ulcer and intestinal metaplasia. ST enhances the development of intestinal metaplasia and increases gastrin levels in H. pylori-infected Mongolian gerbils.     

Rebamipide prevents delay of acetic acid-induced gastric ulcer healing caused by Helicobacter pylori infection in Mongolian gerbils

In this study, we examined the effect of rebamipide, a mucoprotective drug, on gastric ulcer healing in Mongolian gerbils infected with H. pylori. Male Mongolian gerbils were inoculated with H. pylori or vehicle alone 12 hr after the production of an acetic acid-induced gastric ulcer. On day 5, the gerbils inoculated with H. pylori were divided into three groups and fed rebamipide-containing diet (0.038%, 60 mg/kg, or 0.0038%, 6 mg/kg), or standard laboratory chow. The gerbils inoculated with the vehicle were fed standard laboratory chow throughout the experiment. The gerbils were killed on day 5, 15, or 30 after ulcer production, and removed stomachs were subjected to calculation of ulcer size, culture for H. pylori, and measurement of myeloperoxidase activity, a marker for neutrophil infiltration, in ulcerated tissue. Apoptotic and proliferating cells of gastric epithelium in ulcer margins were detected by the in situ DNA nick end-labeling method and immunohistochemical staining for 5-bromo-2'-deoxyuridine (BrdU), respectively. Rebamipide did not affect colonization levels of H. pylori. Infection with H. pylori did not affect ulcer size by day 5 but significantly delayed ulcer healing by days 15 and 30, accompanied by an increase in the number of apoptotic cells, a decrease in the number of BrdU-positive cells, and an increase in myeloperoxydase activity. Rebamipide prevented delay of ulcer healing and abolished these effects of H. pylori on cell kinetics and neutrophil infiltration. In conclusion, rebamipide may prevent the delay of acetic acid-induced gastric ulcer healing caused by H. pylori through modulating cell kinetics and inhibiting neutrophil infiltration.     

Influence of Helicobacter pylori Infection on Healing and Relapse of Acetic Acid Ulcers in Mongolian Gerbils

Both Helicobacter pylori and NSAIDs play important roles in the healing and relapse of peptic ulcers in man. We examined how H. pylori infection, indomethacin, and their combination affects the healing of gastric ulcers and whether or not such factors provoke a relapse of healed gastric ulcers in Mongolian gerbils. Gastric ulcers were induced by serosal application of an acetic acid solution. H. pylori (ATCC43504) was orally administered once into animals with active and healed ulcers. Ulcers healed within eight weeks and remained healed for the following six months. H. pylori infection significantly delayed ulcer healing four weeks following infection. Indomethacin treatment showed a tendency to delay ulcer healing. Ulcer healing in H. pylori-infected Mongolian gerbils was significantly delayed by indomethacin. H. pylori infection resulted in a relapse of healed ulcers from one to six months after infection, with a gradual increase in size. By the fourth month following a relapse, the serum gastrin level had significantly increased. H. pylori-induced ulcers in the posterior wall coexisted with relapsed ulcers in the anterior wall five and six months later. Omeprazole markedly prevented the ulcer relapse caused by H. pylori infection. It is concluded that, in Mongolian gerbils, H. pylori infection delayed the healing of preexisting gastric ulcers and resulted in the relapse of healed ulcers, yet indomethacin had little or no effect on ulcer healing or relapse.     

Duodenogastric Reflux and Helicobacter pylori Infection Synergistically Increase Gastric Mucosal Cell Proliferative Activity in Mongolian Gerbils

Background: Helicobacter pylori and duodenogastric reflux (DGR) are both recognized as aetiological factors in chronic gastritis and gastric carcinogenesis. In this study, a Mongolian gerbil (MG) model was used to investigate the histopathological changes in the gastric mucosa resulting from DGR and/or H. pylori infection. Methods: One-hundred-and-eleven 7-week-old, specific-pathogen-free, male MGs were divided into four groups: normal controls, gerbils with surgically induced DGR, and H. pylori-infected gerbils with and without DGR. Gerbils were killed 4, 12 and 26 weeks after DGR surgery, their stomachs removed and sections prepared. Sections were fixed immediately in 20% phosphate-buffered formalin and subjected to haematoxylin and eosin staining, Alcian blue at pH 2.5/periodic acid-Schiff staining, and immunostaining for smooth muscle cells, H. pylori and 5′-bromo-2′-deoxyuridine (BrdU). Results: The gastric mucosa of H. pylori-infected gerbils showed chronic active gastritis irrespective of DGR throughout the experimental period. The gastric mucosa of H. pylori-infected gerbils with DGR demonstrated higher BrdU labelling than in the other groups. Conclusions: In MGs, DGR and H. pylori infection synergistically increased gastric mucosal cell proliferative activity. DGR and H. pylori infection may be involved synergistically in gastric carcinogenesis by increasing cell proliferative activity.     

Suppressive effect of rice extract on Helicobacter pylori infection in a Mongolian gerbil model

Background Rice extract has been shown to protect gastric mucosa from stress-induced damage. In this study, the antibiotic effect and the anti-inflammatory effect of orally administered aqueous rice extract on Helicobacter pylori infection and H. pylori-induced gastritis, respectively, in Mongolian gerbils were investigated.Methods Fifty specific-pathogen-free male Mongolian gerbils, seven weeks old, were divided into four groups: uninfected, untreated animals (group A); uninfected, rice extract-treated animals (group B); H. pylori-infected, untreated animals (group C); and H. pylori-infected, rice extract-treated animals (group D). Group C and D animals were killed 12 weeks after H. pylori infection (i.e., at 19 weeks of age) and group A and B animals were also killed at age 19 weeks. The stomachs were removed for histopathological examination with hematoxylin-and-eosin staining and anti-5-bromo-2-deoxyuridine (BrdU) immunostaining, and to determine the bacterial burden. Serum anti-H. pylori antibody titers were also tested.Results In groups A and B, the gastric mucosa showed no inflammatory cell infiltration and a few BrdU-reactive cells. Group C animals developed marked chronic active gastritis in the gastric mucosa, and BrdU-labeled cells in the gastric mucosa markedly increased in number. In group D animals, a significant reduction occurred in the degree of neutrophilic polymorphonuclear cell infiltration into the gastric mucosa, in the BrdU-labeling indices of gastric epithelial cells, and in anti-H. pylori antibody titers in the serum (P < 0.01), compared with although H. pylori was not completely eradicated.Conclusions The rice extract was effective in suppressing inflammation and epithelial cell proliferation in the gastric mucosa in H. pylori-infected Mongolian gerbils. The rice extract has potential to exhibit a protective effect on H. pylori-related gastric mucosal diseases.     

Comparative evaluation of urine-based and other minimally invasive methods for the diagnosis of Helicobacter pylori infection

Background: Diagnostic methods have recently been developed for detecting anti-Helicobacter pylori antibody in urine and H. pylori antigen in stool samples. Our aim was to evaluate the usefulness of noninvasive urine-based methods for the diagnosis of H. pylori infection. Methods: The study subjects were 100 asymptomatic Japanese volunteers. We investigated the diagnostic efficacy of various noninvasive diagnostic methods; five serological tests (Immunis anti-pylori, HM-CAP, EIAgen Helicobacter pylori IgG, Helico G, and GAP-IgG), one test for antigen in stool (HpSA enzyme immunoassay [EIA]), and two tests for antibody in urine (Urinelisa and Rapirun) by using the urea breath test (UBT) as the gold standard. Results: Fifty subjects were diagnosed as positive for H. pylori infection by the UBT. The serological tests showed good sensitivity, specificity, and accuracy. The diagnostic values of the feces-based test (HpSA EIA) were lower than that of the serological tests. The sensitivities of the two urine-based methods in frozen urine samples were markedly lower than those of the other tests. However, the use of unfrozen samples markedly improved the diagnostic accuracy of these urine-based tests, which was then superior to that of the feces-based method. Conclusions: This study clearly showed that urine-based tests were useful for the diagnosis of H. pylori infection. However, the use of frozen urine samples was not appropriate for the detection of anti-H. pylori antibody. Received: November 5, 2001 / Accepted: February 22, 2002 Acknowledgments. We wish to thank Ms. Rika Tohma, Ms. Shiho Yamamoto, Ms. Yukiko Inoue, Mr. Masahiro Ishibashi, and Mr. Nobuo Sasaki for their technical supports. This work was supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education, Science, and Culture of Japan. Reprint requests to: K. Adachi     

Antibacterial action of tryptanthrin and kaempferol, isolated from the indigo plant (Polygonum tinctorium Lour.), against Helicobacter pylori-infected Mongolian gerbils

We evaluated the effect of tryptanthrin and kaempferol, both isolated from Polygonum tinctorium Lour., against Helicobacter pylori colony formation in vitro and in H. pylori-infected Mongolian gerbils. H. pylori suspension was mixed with solution of tryptanthrin and/or kaempferol and placed onto agar plates. These plates were incubated at 37°C, under 10% CO₂ for 5 days, and the H. pylori colonies were counted. For the in vivo experiment, Mongolian gerbils were inoculated with H. pylori ATCC 43504 orally. After 4 weeks, the infected gerbils were given tryptanthrin and/or kaempferol, administered orally, twice a day for 10 days. The animals were killed and the number of live H. pylori in their stomachs was determined. In vitro both tryptanthrin and kaempferol significantly decreased the numbers of H. pylori colonies a dose-dependent manner. An additive effect on colony formation was observed with the combined use. In the in vivo experiment, oral administration of tryptanthrin and/or kaempferol significantly decreased the numbers of colonies in the gerbils' stomachs. We concluded that tryptanthrin and kaempferol were effective against H. pylori in vivo. Received: December 27, 1999 / Accepted: July 28, 2000     

Discrepancy between Helicobacter pylori stool antigen assay and urea breath test in the detection of Helicobacter pylori infection

Background. The reference diagnostic methods available for detection of Helicobacter pylori infection are either invasive (histology) or expensive and highly sophisticated (Urea Breath Test). A new enzyme immunoassay, which can be easily performed in any laboratory, has been developed to detect Helicobacter pylori in stool specimens (HpSA - Meridian Diagnostics, Cincinnati, USA). Aim of the study was to compare HpSA to Urea Breath Test.Patients and methods. A total of 125 patients (52 never treated for Helicobacter pylori infection and 73 after Helicobacter pylori eradication therapy) referring to our Department, underwent both tests within two weeks.Results. Contrasting results between the two tests were found in 30% of cases: in 19% of the untreated patients and in 37% of the treated patients (p<0.001). The main discrepancy consisted in positive HpSA associated with negative Urea Breath Test. Mean HpSA value in such conditions was 0.273 optical density, while in patients with both positive tests, it was 1.192 optical density. In untreated, but not in treated patients, raising the HpSA cut off value significantly decreased the percentage of conflicting results.Conclusions. Some disagreement was detected between HpSA and Urea Breath Test results, especially in treated patients. Possible explanations for our findings are a low HpSA cut off value together with the identification of Helicobacter pylori coccoid forms by the immunoassay but not by the urease based Urea Breath Test. The higher percentage of discrepancy detected in treated patients might support this hypothesis.     

Evaluating the validity of the serologic test for detecting Helicobacter pylori infection in Mongolian gerbils

A strong correlation between Helicobacter pylori infection and gastric cancer has been reported. Mongolian gerbils are regarded as the most suitable animal model in which to study carcinogenesis associated with H. pylori. The aim of our study was to evaluate the accuracy of the serologic test for detecting H. pylori infection in Mongolian gerbils. The model was developed as follows: the H. pylori colony (vacuolating cytotoxin A (+)/cytotoxin-associated gene A (+)) was cultured from the mucosas of previously H. pylori-fed gerbils. These colonies were cultured in broth. Then,we fed the gerbils with 0.5-1 mL of broth (about 10(9) CFU/mL) (intragastric administration) twice within a 3-day period. After inoculation for 6 or 26 weeks, the gerbils were sacrificed and their gastric mucosas were sampled for a series of examinations. Blood samples for serologic testing (STAT-PAK) were collected. H. pylori infection was confirmed. Statistical analysis was performed using the Chi-square test. Differences were regarded as significant when the p value was less than 0.05. A total of 50 gerbils were inoculated with H. pylori and the success rate reached 88%. All 10 gerbils in the control group showed a negative result. Damage to the mucosas was more obvious following increasing periods of inoculation. The rates of sensitivity and specificity, as determined by the STAT-PAK test, were 90.9% and 100%, respectively. The positive and negative predictive values were 100% and 60%, respectively. The STAT-PAK test seemed to be more sensitive and accurate (p < 0.05) in high H. pylori densities. In conclusion, the STAT-PAK test (blood-sampling) showed acceptable results and was suitable for long-term observation of H. pylori infection.