13C-urea breath test and gastric mucosal colonization by Helicobacter pylori in children: quantitative relation and usefulness for diagnosis of infection

Objective. Because in children Helicobacter pylori colonization could differ as compared to that in adults, gastric metabolism of urea and the reliability of the breath test must be evaluated. The aim of this study was to quantify the relationship between breath test and colonization.
Methodology. We studied data from 50 endoscopies performed in 39 children and adolescents (20 girls, 19 boys, aged 3–18 years); 28 were infected with H. pylori. Biopsies were analyzed for histological and microbiological diagnosis of infection and for quantitative antral culture of H. pylori. A ¹³C urea breath test was performed on the same day as that of endoscopy ( n = 33) or delayed between 2 and 90 days ( n = 17).
Results. Using a cut-off value of 3 δ‰, sensitivity was 96.5%, and specificity was 91.5%. The three children showing discrepancies between breath test and biopsy results had a δ‰ value close to the cut-off. For the 26 cases with a positive culture, we noted a significant correlation (r = 0.63; p < .001) that was not affected by the delay between breath test and gastroscopy.
Conclusion. This quantitative relation between bacterial density and δ‰ permits increasing the reliability of the test by interpreting carefully those results that approach the cut-off value.     

Comparison of two different stool antigen tests for the primary diagnosis of Helicobacter pylori infection in turkish patients with dyspepsia

AIM: To assess the reliability of two different enzyme immunoassays in detecting the Helicobacter pylori status in stool specimens of Turkish patients with dyspepsia. MATERIALS AND METHODS: One hundred and fifty-one patients [74 with nonulcer dyspepsia (NUD), 64 with duodenal ulcer (DU) and 13 with gastric cancer] who were admitted to the endoscopy unit of Istanbul University, Cerrahpasa Medical Faculty for upper gastrointestinal endoscopy because of dyspepsia were enrolled in the study. Helicobacter pylori infection was confirmed in all patients by histology, rapid urease test and culture. A patient was classified as being H. pylori-positive if the culture alone or both the histology and the rapid urease test were positive and as negative only if all of these tests remained negative. Stool samples were obtained from patients to assess the reliability of a monoclonal (FemtoLab H. pylori) and a polyclonal (Premier Platinum HpSA) stool antigen test and to compare the diagnostic accuracies of these two tests. A chi2 test was used for statistical comparisons. RESULTS: Using cut-off values of 0.19 for FemtoLab H. pylori and 0.16 for Premier Platinum HpSA, the sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were 93%, 90%, 98%, 68% and 93% for the monoclonal test and 84%, 67%, 94%, 40% and 81% for the polyclonal test, respectively. The sensitivity, specificity, negative predictive value and diagnostic accuracy of the monoclonal test were significantly greater than those of the polyclonal test (chi2 = 3.98; p < .05 for sensitivity and chi2 = 15.67; p = .000 for specificity, chi2 = 15.78; p = .000 for negative predictive value and chi2 = 6.37; p = .012 for diagnostic accuracy). The bacterial load did not affect the sensitivity of either test. CONCLUSIONS: The monoclonal FemtoLab H pylori test, using a cut-off 0.19, is a very sensitive, specific and easy to perform diagnostic tool for the primary diagnosis of H. pylori infection in Turkish patients with dyspepsia.     

Novel monoclonal antibody-based Helicobacter pylori stool antigen test

BACKGROUND: A number of noninvasive tests have been developed to establish the presence of Helicobacter pylori infection. Although polyclonal antibody-based stool antigen testing has a good sensitivity and specificity, it is less accurate than urea breath testing. Recently, a monoclonal antibody-based stool antigen test demonstrated an excellent performance in diagnosing H. pylori infection in adults and in pediatric populations. AIM: To evaluate the diagnostic accuracy of a novel stool test based on monoclonal antibodies to detect H. pylori antigens in frozen human stool in the pretreatment setting. PATIENTS AND METHODS: Stool specimens were prospectively collected from 78 patients undergoing gastroscopy and stored at -20 degrees C until tested. Helicobacter pylori infection was evaluated by histology, rapid urease testing and urea breath tests ((13)C-UBT). Positivity of the three tests was considered the gold standard for H. pylori active infection. Patients with no positive test were considered negative. The gold standard was compare to the results of the monoclonal antibody stool antigen test. Frozen stool specimens were tested using a novel monoclonal-antibody-based enzyme immunoassay (HePy-Stool, Biolife-Italiana, Milan, Italy). RESULTS: The sensitivity and specificity of the monoclonal stool antigen test were 97%[95% confidence interval, (CI) 86-100] and 94% (95% CI: 81-99), respectively. Negative and positive predictive values were 97% (95% CI: 85-99), and 95% (95% CI: 83-99), respectively. The diagnostic accuracy was 96% (95% CI: 88-99). The likelihood ratio for a positive test was 17 and for a negative test was 0. CONCLUSIONS: Although the (13)C-UBT is the most accurate among the available noninvasive tests, our results show that an H. pylori stool test using monoclonal antibody might be an excellent alternative.     

Endoscopic Tests for the Diagnosis of Helicobacter pylori Infection in Children: Validation of Rapid Urease Test

Background: Rapid urease test (CLO‐test) is an inexpensive and quick method for diagnosis of Helicobacter pylori infection with controversial results in children. We evaluated the performance of CLO‐test in relation to endoscopic and histological findings in children with H. pylori infection. Materials and methods: We studied the medical records of c hildren with H. pylori infection who were diagnosed between 1989 and 2009. Noninfected children were used as controls. H. pylori infection was defined by positive culture or by two other positive tests (histology and CLO‐test, or urea breath test when a single test was positive). All children had histology together with CLO‐test. Tissue culture was performed whenever possible. Results: Five hundred thirty infected children (10.4 ± 3.0 years) and 1060 controls (7.3 ± 4.4 years) were studied. Sensitivity of CLO‐test was 83.4% (95% CI, 79.9–86.3%), of culture 84.6% (95% CI, 78.7–89.1%), of histology 93.2% (95% CI, 90.7–95.1%), and specificity 99% (95% CI, 98.2–99.4%), 100%, and 100% respectively. CLO‐test positivity was correlated with higher bacterial density (p < .001), activity (p < .001) and severity of gastritis (p < .01), older age (p < .01), and the presence of antral nodularity (p < .001). When CLO‐test was positive, the concordance with histology and culture was high (95.5 and 89.2% respectively), whereas low concordance was observed when CLO‐test was negative (17.05 and 45.83% respectively). Conclusions: CLO‐test had lower sensitivity and comparable specificity with histology. Both tests should be performed concurrently to accurately diagnose H. pylori infection in children.     

Factors that affect results of the 13C urea breath test in Japanese patients

Background. The ¹³C urea breath test (UBT) is considered to be the most accurate way of diagnosing Helicobacter pylori infection. Our objective was to investigate the accuracy of the UBT in Japanese patients and the association of UBT values with histological findings.
Materials and Methods. A total of 169 consecutive patients were studied by endoscopy with histology, by serology with IgG antibody and test serum pepsinogen (PG), and by UBT. The association between UBT values and histological findings and the PG I / II ratio were analyzed in H. pylori –positive patients.
Results. Of 169 Japanese patients, 135 were H. pylori –positive on both histology and serology analysis, 27 were H. pylori –negative on both histology and serology analysis, and 7 patients showed differing results. Using a cutoff value of 2.5‰, test sensitivity was 100%, while specificity was 96%. Among the 135 H. pylori –positive patients, a significant relation was observed between UBT value and H. pylori colonization density of the corpus and antrum, neutrophil activity of the antrum, atrophy, and intestinal metaplasia of the corpus in the H. pylori –positive patients. Also, UBT values correlated with the PG I /II ratio. In multivariate analysis, the PG I /II ratio was the most important factor related to UBT values (odds ration [OR], 4.99; 95% confidence interval, 1.60–15.55).
Conclusions. The UBT is an accurate method for detecting H. pylori infection in the Japanese population, which shows a high prevalence of atrophic gastritis. Values are affected by H. pylori infection and by the severity of atrophic gastritis.     

Pantoprazole suppresses Helicobacter pylori without affecting cure

Background. Short-term, low-dose triple regimens composed of proton-pump inhibitors (PPI) and two antibiotics are the current gold standard therapy for cure of Helicobacter pylori infection. To date, the effect of PPI pretreatment on eradication outcome is not known. The aim of this study was to evaluate the influence of pretreatment with pantoprazole on the efficacy of an ensuing triple therapy.
Methods. In this open, randomized, monocenter, parallel group comparison, 107 patients with duodenal ulcer or functional dyspepsia were assigned to receive one of the following treatment regimens: a 7-day triple therapy with pantoprazole, 40 mg bid; clarithromycin, 250 mg bid; and metronidazole, 400 mg bid, which was either preceded or followed by a 7-day therapy with pantoprazole, 40 mg (P-PCM or PCM-P). Assessment of H. pylori status was performed by a biopsy urease test and ¹³C urea breath test at the initial visit and ¹³C urea breath test at all follow-up visits.
Results. The 7-day pantoprazole pretreatment resulted in a significant decline of the δ values of the ¹³C urea breath test. H. pylori infection was cured in 47 of 52 intention-to-treat patients of the P-PCM group (90%; 95% confidence interval, 79–97%) and in 46 of 53 of the PCM-P group (87%; 95% confidence interval, 75–95%).
Conclusions. Pretreatment with pantoprazole suppresses H. pylori but does not impair the efficacy of a consecutive short-term, low-dose triple therapy.     

Detection of specific Helicobacter pylori DNA and antigens in stool samples in dyspeptic patients and healthy subjects

In this study stool samples from dyspeptic patients and healthy subjects were used for detection of specific Helicobacter pylori antigens and DNA by immunoenzymatic test (PPHpSA) and semi-nested PCR (ureA-PCR), respectively. The H. pylori status was estimated by invasive endoscopy-based rapid urease test and histology or noninvasive urea breath test (UBT), and by serology (ELISA, Western blot). The coincidence of H. pylori-negative invasive tests or UBT and negative antigen or DNA stool tests was very high (mean 95%). The PPHpSA results were found positive for 56% and ureA-PCR for 26% of individuals with H. pylori infection confirmed by invasive tests or UBT. The detection of specific H. pylori antigens and especially DNA in feces is not sufficient as a one-step diagnosis of H. pylori infection.     

13C-Urea breath test is superior in sensitivity to detect Helicobacter pylori infection than either antral histology or rapid urease test.

There is no single technique which fulfils the criterion for a reference method to detect Helicobacter pylori (Hp) infection. The aim was to compare the results of antral histology (H), rapid urease test (U) and urea breath test (UBT) from antral biopsy samples in patients having gastric or duodenal lesions during upper GI endoscopy. We used the following methods: 1) biopsy specimens for histology (Warthin-Starry staining); 2) rapid urease test; and 3) 13C-urea breath test with infrared spectrometry. The total number of patients was 166 examined by H, U, and UBT. H, U and UBT were negative (-) in 64 patients and positive (+) in 51. The true positivity and false negativity (%, number of patients in parentheses) of each method based upon the positivity of the other two tests were: H+, U+ (54): UBT+, 94.4% (51) and UBT-, 5.6% (3); H+, UBT+ (57): U+, 89.5% (51) and U-, 10.5% (6); U+, UBT+ (65): H+, 78.5% (51) and H-, 21.5% (14). If Hp infection is considered to be positive when at least two tests detect the presence of Hp, UBT shows the highest sensitivity in comparison to histology of biopsy specimens and urease test. UBT is highly recommended as a screening test for Hp infection in patients presenting upper GI endoscopic alterations.     

Factors affecting the validity of the 13C-urea breath test for in vivo determination of Helicobacter pylori infection status in a mouse model

Background. The mouse model using a human isolate of Helicobacter pylori is being widely accepted as an economical means of studying gastric infection. A noninvasive monitoring method would be useful for repeated testing to establish the time course of infection and the efficacy of treatments. In this study, we describe factors that affect interpretation of ¹³C urea breath test results for the assessment of H. pylori infection status in this model.
Materials and Methods. Female C57Bl/6 mice that underwent gavage with H. pylori or saline were breath-tested using 50 μg of ¹³C urea at intervals up to 2 months after inoculation. The generation of ¹³CO₂ (excess δ¹³CO₂) by infected mice was compared to that of uninfected controls. The effects of diet, fasting, and coprophagy on the reliability of the ¹³C urea breath test were quantitated.
Results. Both commercial and synthetic mouse diets exhibited marked in vitro urease activity. A minimum fasting time of 13 hours prior to breath testing significantly reduced this dietary contribution to excess δ¹³CO₂ values. The coprophagic tendency of the mice caused spuriously high excess δ¹³CO₂ counts in the breath of both control and H. pylori –infected mice.
Conclusions. Although the dietary contribution to spuriously high values of excess δ¹³CO₂ in mice breath-tested for H. pylori infection was reduced by fasting, the high nonspecific urease activity generated by coprophagy severely limited the reliability of the urea breath test in the assessment of H. pylori infection status.     

Helicobacter pylori infection in Turkish children: comparison of diagnostic tests, evaluation of eradication rate, and changes in symptoms after eradication

BACKGROUND: Helicobacter pylori infection is most frequently acquired in childhood. After this organism is eradicated, the rate of reinfection is low. Thus, it is very important to diagnose and treat the disease appropriately in childhood, and to be able to assess eradication with certainty. Eradication of H. pylori infection is reported to reduce or eliminate abdominal pain and dyspeptic symptoms in children. PATIENTS AND METHODS: The study involved 102 children who had already been diagnosed with symptomatic H. pylori infection based on gastric histopathological examination, urea breath test, rapid urease test, serology and culture. Each patient's symptoms and family history of gastrointestinal problems were recorded. Using histology as the gold standard for identifying H. pylori infection, we determined the diagnostic sensitivity of each of the other methods. Omeprazole or lansoprazole, amoxicillin and clarithromycin were administered as eradication treatment, and each patient was re-evaluated by urea breath test 8 weeks later. Each child was re-interviewed about symptoms after treatment. These answers and the results of drug sensitivity testing were recorded. Cases of failed eradication were re-treated with a quadruple-drug regimen of tetracycline, metronidazole, bismuth subsalicylate and omeprazole. RESULTS: The most frequent symptom was abdominal pain (89.2%). Fifty-four per cent of the subjects had a family history of dyspeptic symptoms. Sixty-six patients (64.7%) exhibited nodularity in the antral mucosa. The sensitivities of the diagnostic tests in histologically proven cases were as follows: urea breath test 100%, rapid urease test 89.2%, serology 71.9%, and culture 54.9%. Metronidazole had the highest frequency of resistance (36.4%) and the rate of clarithromycin resistance was 18.2%. The eradication rate after first-line therapy was 75.5%, and abdominal pain and dyspeptic symptoms were reduced or completely resolved in 75.7% of the successful-eradication cases. The proportion of failed-eradication cases that responded well to quadruple-drug therapy was 93.8%. CONCLUSION: Symptomatic H. pylori infection in a child should always be treated. The urea breath test is an accurate and reliable way to identify H. pylori-positive patients and to determine the response to treatment. Triple-agent therapy is effective for eradicating H. pylori infection in children and usually helps reduce or eliminate dyspeptic symptoms. The level of H. pylori resistance to metronidazole is high in our region. The significant rate of resistance to clarithromycin (18.1%) may explain the treatment failure observed in this study.     

慢性腹痛患儿C~(13)-尿素呼气试验与胃镜检查的临床意义

目的了解慢性腹痛患儿幽门螺杆菌(H.pylori)的感染状态及幽门螺杆菌感染患儿内镜下表现的特点。方法应用C13尿素呼气试验,对905例以慢性腹痛为主要症状的患儿进行检测,对C13呼气试验阳性者进行电子胃镜检查。结果905例慢性腹痛患儿中H.pylori呈阳性185例(20.44%),随年龄增长,其H.pylori阳性率升高,学年组已达高峰。对H.pylori阳性者进行胃镜检查结果显示十二指肠隆起病变47例占25.40%,结节性胃炎41例占22.1%,慢性浅表性`胃炎38例占20.5%,结节性胃炎伴十二指肠隆起病变23例占12.43%,十二指肠球部溃疡23例占12.4%。胃溃疡7例,占3.7%(其中包括1例复合性溃疡),结节性胃炎伴十二指肠炎6例,占3.2%。结论H.pylori感染为小儿慢性腹痛的主要原因之一,也是导致慢性胃炎及消化性溃疡的主要原因之一。C13尿素呼气试验方便,快速,无痛苦,无放射性,是一较好的H.pylori检测方法;对既有消化道症状同时C13呼气试验阳性者进行胃镜检查能够协助临床诊断及治疗。     

Usefulness of non-invasive tests for diagnosing Helicobacter pylori infection in patients undergoing dialysis for chronic renal failure

BACKGROUND: Helicobacter pylori infection in chronic renal failure patients has been linked to peptic ulcer and gastric neoplasia after kidney transplantation. It may also contribute to the accelerated arteriosclerosis that is usual in this population. Few data are available on the usefulness of noninvasive diagnostic tests for H. pylori infection in dialyzed patients, especially regarding the new fecal antigen detection tests. The objective of this study was to determine the efficacy of a noninvasive test for H. pylori infection in patients with chronic renal failure. METHODS: Eighty-six patients were included in a cross-sectional study. Urea breath test, serology and three fecal tests--FemtoLab H. pylori (Connex, Germany), Premier Platinum HpSA (Meridian, USA) and Simple H. pylori (Operon SA, Spain) were performed. Helicobacter pylori status was determined by concordance of the tests. Sensitivity, specificity and positive and negative predictive values were calculated for each test. RESULTS: Sensitivity, specificity, positive and negative predictive values were 94%, 96%, 94% and 96% for the urea breath test; 97%, 64%, 66% and 97% for serology; 86%, 100%, 100% and 91%, for FemtoLab H. pylori; 58%, 96%, 91% and 76% for Premier Platinum HpSA and 61%, 78%, 74% and 67% for Simple H. pylori. CONCLUSIONS: The urea breath test seems to be the most reliable diagnostic method for H. pylori infection in patients with chronic renal failure. Serology has a low specificity, and the results of the fecal tests vary widely.     

幽门螺杆菌感染与慢性口臭关系的初步研究

目的 调查主诉口臭患者的幽门螺杆菌（H．pylori）感染率和主诉消化不良的口臭发生率。方法 研究对象为125例主诉慢性口臭患者和212例主诉慢性消化不良患者。口臭以口气挥发性硫化物（VSC）检测与闻诊联合诊断,H．pylori感染以^14C-尿素呼气试验诊断。结果 125例主诉慢性口臭的患者有87例是真性口臭,其余38例为假性口臭,真性口臭患者的H．pylori感染率显著高于假性口臭（40．2％和13．2％,P〈0．01）。212例主诉慢性消化不良的患者发生口臭105例（49．5％）、感染H．pylori 94例（44．3％）,H．pylori阳性患者的口臭发生率显著高于H．pylori阴性患者（57．5％和43．2％,P〈0．05）。无论何种主诉,大部分口臭患者属于VSC阳性（88．5％）,但H．pylori阳性患者和H．pylor阴性患者口气VSC水平差异无显著性,VSC阳性口臭和VSC阴性口臭的H．pylori感染率差异也无显著性。结论 H．pylori感染可能与口臭的发生有一定关系,但口气VSC并非由H．pylori直接产生。     

Urea Breath Test in Children: The United States Prospective, Multicenter Study

Background: The urea breath test (UBT) is generally considered the gold standard for the diagnosis of Helicobacter pylori infections in adults.
Goals: To investigate the utility and accuracy of urea breath testing in children from the United States.
Methods: Children scheduled to undergo upper gastrointestinal endoscopy for various clinical symptoms underwent a ¹³C-UBT using the US standard protocol for adults. Results were compared with rapid urease testing (RUT), culture, and histology. H. pylori positivity was defined according to the FDA, Division of Anti-Infective Drug Products criteria, i.e. positive culture and/or positive RUT and histology. H. pylori negativity was defined as all tests negative. Results were evaluated by delta over baseline (DOB) and urea hydrolysis rate (UHR).
Results: A total of 176 children from five centers were evaluated; 48 were infected. Compared to the defined standard, the results with the UBT based on delta over baseline (DOB) cut-off value (positive: ≥ 2.4‰) showed that the sensitivity and specificity of the UBT were 97.9% and 96.1%, respectively. Based on the UHR cut-off value (positive: ≥ 10.0 µg/min), the sensitivity and specificity were 95.8% and 99.2%. In young children (2- to 5-year olds), sensitivity and specificity of UHR method were higher than the DOB method (100% and 100% vs 100% and 82.4%, respectively).
Conclusion: The US standard ¹³C-UBT proved to be both simple and accurate for the diagnosis of H. pylori infections in children. The UHR method to calculate of ¹³C-UBT result provided excellent results for children of all ages.     

Testing for Helicobacter pylori infection: validation and diagnostic yield of a near patient test in primary care

ObjectiveTo evaluate the performance of a near patient test for Helicobacter pylori infection in primary care.DesignValidation study performed within a randomised trial of four management strategies for dyspepsia.Setting43 general practices around Nottingham.Subjects394 patients aged 18-70 years presenting with recent onset dyspepsia.ResultsWhen used in primary care FlexSure test had a sensitivity and specificity of 67% (95% confidence interval 59% to 75%) and 98% (95% to 99%) compared with a sensitivity and specificity of 92% (87% to 97%) and 90% (83% to 97%) when used previously in secondary care. Of the H pylori test and refer group 14% (28/199) were found to have conditions for which H pylori eradication was appropriate compared with 23% (39/170) of the group referred directly for endoscopy.ConclusionsWhen used in primary care the sensitivity of the FlexSure test was significantly poorer than in secondary care. About a third of patients who would have benefited from H pylori eradication were not detected. Near patient tests need to be validated in primary care before they are incorporated into management policies for dyspepsia.

Key messages

• Near patient tests for H pylori infection have been recommended in the management of dyspepsia in primary care without proper evaluation
• Such tests should have a high sensitivity to avoid missing treatable illness related to infection
• The FlexSure near patient test had a lower sensitivity than previously reported in validation studies performed in secondary care
• Fewer than expected numbers of patients with H pylori related pathology were identified with the FlexSure in primary care

     

Multicenter comparison of rapid lateral flow stool antigen immunoassay and stool antigen enzyme immunoassay for the diagnosis of Helicobacter pylori infection in children

BACKGROUND AND AIM: The stool antigen enzyme immunoassay (EIA) methods are widely used for diagnosing Helicobacter pylori infection. Recently, a novel, rapid stool antigen test, the lateral flow immunoassay (LFI) method, has been developed. The primary purpose of this study was to compare the EIA method with the LFI method for the diagnosis of H. pylori infection in children. MATERIALS AND METHODS: Stool specimens from children being evaluated for H. pylori infection were also examined using the LFI (ImmunoCard STAT! HpSA) and EIA methods (Premier Platinum HpSA). The sensitivity, specificity and accuracy of the test were based on the 13C-labeled urea breath test. RESULTS: One hundred and eighty-two children and adolescents, 3-17 years of age (mean 9.2 years), were studied. In addition, 29 patients who received eradication therapy were re-evaluated 2 or 3 months post-treatment. The 13C-labeled urea breath test was positive in 64 patients (35.2%). The sensitivity, specificity and accuracy of the LFI method were 90.6% (95% CI = 80.7-96.5%), 95.8% (92.1-99.4%), and 94.0% (90.5-97.4%), respectively and for the EIA method, sensitivity, specificity and accuracy were 96.8% (95% CI, 89.0-99.6%) and 99.2% (97.5-100%), and 98.3% (96.5-100%), respectively. There were no significant differences in results among the age groups 3-5, 6-10 and 11-17 years. As for the assessment of H. pylori eradication, the results of the LFI and EIA methods agreed with those of 13C-urea breath test in 27/29 and 29/29 patients, respectively. CONCLUSIONS: The LFI stool antigen method showed a good sensitivity, specificity and accuracy for diagnosing H. pylori infection in children. This novel method may be useful in clinical practice as an office-based test because it is rapid, reliable and easy to perform.     

Helicobacter pylori and smoking: two additive risk factors for organic dyspepsia.

The hopes to distinguish between organic and functional dyspepsia on the grounds of the patient's symptomatology have not been fulfilled due to the low specificity of the so-called sinister symptoms. There is increasing evidence accumulating that Helicobacter pylori status and other environmental factors such as smoking have a higher discriminant power. Studies performed in our laboratories testing H. pylori status on gastric biopsy samples have shown that preselection of patients according to smoking habits and H. pylori status has a higher potential in avoiding unnecessary endoscopies in primary care patients as compared to risk factors based on patient complaints. Out of a total population of 282 primary care patients, one out of 24 endoscopies revealed significant pathology such as peptic ulcer or reflux esophagitis in the non-smokers with a negative H. pylori status, but when both risk factors were positive, the percentage rose to one out of every two patients. These observation have largely been confirmed by recent studies where H. pylori status was prospectively assessed prior to endoscopy by highly specific H. pylori serology or 13C breath test analysis.     

Quadruple therapy is effective for eradicating Helicobacter pylori after failure of triple proton-pump inhibitor-based therapy: a detailed, prospective analysis of 21 consecutive cases

Background. Data regarding the effectiveness of second-line treatment of Helicobacter pylori infection are limited, especially if microbiological studies are considered.
Methods and Patients. We conducted a prospective, uncontrolled study of a consecutive series of 21 peptic ulcer patients with failure of 1-week lansoprazole, amoxicillin, and clarithromycin. H. pylori status was evaluated by urease test, histology, culture, and urea breath test. Susceptibility to amoxicillin, clarithromycin, and metronidazole was studied by E -test. Cure of infection was defined as negative results from endoscopy-based tests 1 month after treatment and negative results from a urea breath test at 2 months. Treatment consisted of a 1-week combination of lansoprazole (30 mg bid), tetracycline (500 mg qid), metronidazole (500 mg tid), and bismuth subcitrate (120 mg qid).
Results. H. pylori was resistant to metronidazole in three cases, to clarithromycin in three cases, and to both clarithromycin and metroinidazole in an additional three patients. No resistance to amoxicillin was found. Eradication was obtained in 20 cases (95.2% confidence interval [CI], 76.2–99.9). The only patient in whom infection was not eradicated harbored a metronidazole-resistant (minimum inhibitory concentration> 32 μg/ml) strain. No significant side effects were reported.
Conclusion. Quadruple therapy obtains a high eradication rate even in patients with clarithromycin- and metronidazole-resistant strains. Further randomized and controlled studies are warranted and are urgently needed.     

13C-urea breath test results in pigs challenged with Helicobacter pylori or other urease producing bacteria

The gastric bacterial flora and its influence on the 13C-urea breath test (UBT) for detection of Helicobacter pylori infection was studied in a pig model. Seven SPF minipigs were used. H. pylori or a mix of other urease positive bacteria were administered orally. UBT, serum and biopsies for histology and culture were collected. Our results show that UBT is not specific for H. pylori in pigs as the gastric bacterial flora is responsible for the high UBT values observed. Furthermore, the Ellegaard G?ttingen SPF minipigs are not useful in an animal model for H. pylori studies.     

Problem of distinguishing false-positive tests from acute or transient Helicobacter pylori infections

BACKGROUND: Reliable detection of acute Helicobacter pylori infections remains problematic. The high prevalence of false-positive non-invasive tests in low H. pylori prevalence populations makes identification of acute and transient infections difficult. METHODS: We explored the use of serum pepsinogens (PG) for diagnosis of acute infection in patients following H. pylori challenge such that the onset of the infection was known. We then compared those findings to a group of children with presumed acute infections defined as a positive urea breath test (UBT) and negative IgG serology. RESULTS: We examined the pattern and calculated cut-off values of PG levels in 18 adult volunteers with known acute H. pylori infection. We then compared the results with sera from nine symptomatic children with presumed acute H. pylori infection and a matched control group of nine children who did not meet criteria for acute H. pylori infection. In acute infection, both PGI and II levels increased following H. pylori infection reaching a peak by 2 weeks post-infection. The frequency of a positive test defined as a value > mean +2 SD was 17, 71, and 94% at week 1, 2, and 4 post-infection, respectively. Only one child with presumed acute H. pylori infection had an elevated serum PGI and one had an elevated PGII. Five of the children had follow-up UBTs and four were negative consistent with the diagnosis of false-positive UBT. H. pylori infection was confirmed in the child with an elevated PGI level. CONCLUSIONS: These data suggest that a single positive noninvasive test in populations of low prevalence is most likely a false-positive result. This suggests that a single positive test requires confirmation preferably using a test that measures a different parameter (e.g., UBT confirmed by stool antigen test). It appears that most "transient"H. pylori infections are diagnosed on the basis of false-positive tests. PG levels are possible candidates as the confirmatory test.