Effect of a test meal on the intragastric distribution of urea in the 13C-urea breath test for Helicobacter pylori

DIAGNOSTIC ACCURACY OF UREA BREATH TEST FOR HELICOBACTER PYLORI INFECTION IN CHILDREN WITH DYSPEPSIA IN COMPARISON TO HISTOPATHOLOGY

ABSTRACT Background - Helicobacter pylori infection is the gram negative bacillus with the close association with chronic antral gastritis. Objective - In this study, we evaluate the accuracy of urea breath test (UBT) with carbon isotope 13 in comparison with histopathology of gastric antrum for detection of H. pylori infection in children with dyspepsia. Methods - This cross-sectional study was performed at specialized laboratory of Shiraz Gastroenterohepatology Research Center and Nemazee Hospital, Iran, during a 12-months period. This study investigated the sensitivity, specificity, and positive and negative predictive values of UBT in comparison with biopsy-based tests. We included a consecutive selection of 60 children who fulfilled Rome III criteria for dyspepsia. All children were referred for performing UBT with carbon isotope 13 (C13) as well as endoscopy. Biopsies were taken from antrum of stomach and duodenum. The pathologic diagnosis was considered as the standard test. Results - The mean age of the participants was 10.1±2.6 (range 7-17 years). From our total 60 patients, 28 (46.7%) had positive UBT results and 32 (53.3%) had negative UBT results. Pathologic report of 16 (57.1%) out of 28 patients who had positive UBT were positive for H. pylori and 12 (42.9%) ones were negative. Sensitivity and specificity of C13-UBT for detection of H. pylori infection were 76.2% and 69.2% respectively. Conclusion - Sensitivity and specificity of C13-UBT for detection of H. pylori infection were 76.2% and 69.2% respectively. Another multicenter study from our country is recommended.

An optimized 13C-urea breath test for the diagnosis of H pylori infection

AIM: To validate an optimized 13C-urea breath test (¹³C-UBT) protocol for the diagnosis of H pylori infection that is cost-efficient and maintains excellent diagnostic accuracy.

METHODS: 70 healthy volunteers were tested with two simplified ¹³C-UBT protocols, with test meal (Protocol 2) and without test meal (Protocol 1). Breath samples were collected at 10, 20 and 30 min after ingestion of 50 mg ¹³C-urea dissolved in 10 mL of water, taken as a single swallow, followed by 200 mL of water (pH 6.0) and a circular motion around the waistline to homogenize the urea solution. Performance of both protocols was analyzed at various cut-off values. Results were validated against the European protocol.

RESULTS: According to the reference protocol, 65.7% individuals were positive for H pylori infection and 34.3% were negative. There were no significant differences in the ability of both protocols to correctly identify positive and negative H pylori individuals. However, only Protocol 1 with no test meal achieved accuracy, sensitivity, specificity, positive and negative predictive values of 100%. The highest values achieved by Protocol 2 were 98.57%, 97.83%, 100%, 100% and 100%, respectively.

CONCLUSION: A 10 min, 50 mg ¹³C-UBT with no test meal using a cut-off value of 2-2.5 is a highly accurate test for the diagnosis of H pylori infection at a reduced cost.

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

BACKGROUND AND AIM

A late rise in (13)CO2 excretion in the (13)C-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 (13)C-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 Delta(13)CO2 values higher than 2.5 per thousand 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 Delta(13)CO2 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.

Is there any correlation between 13C-urea breath test values and response to first-line and rescue Helicobacter pylori eradication therapies?

AIM

To study if there is a correlation between 13C-urea breath test values prior to treatment and the response to first-line and rescue Helicobacter pylori eradication therapies.

METHODS

Six-hundred patients with peptic ulcer or functional dyspepsia infected by H. pylori were prospectively studied. Pre-treatment H. pylori infection was established by 13C-urea breath test. Three-hundred and twelve patients were treated with first-line eradication regimen, and 288 received a rescue regimen. H. pylori eradication was defined as a negative 13C-urea breath test, 8 weeks after completion of treatment.

RESULTS

H. pylori eradication was achieved in 444 patients. No statistically significant differences were demonstrated when mean delta 13C-urea breath test values were compared between patients with eradication success and failure (49.4+/-33 versus 49.2+/-31). Differences in mean pre-treatment delta 13CO2 between patients with eradication success/failure were not demonstrated either when first-line or rescue regimens were prescribed. With the cut-off point of pre-treatment delta 13CO2 set at 35 units, sensitivity and specificity for the prediction of H. pylori eradication success was 43 and 60%. The area under the receiver operating characteristic curve evaluating all the cut-off points of the pre-treatment delta 13CO2 for the diagnosis of H. pylori eradication was 0.5. Finally, delta 13CO2 values did not influence the eradication in the logistic regression model.

CONCLUSION

No correlation was observed between 13C-urea breath test values before treatment and the response to first-line and rescue H. pylori eradication therapies. Therefore, we conclude that the quantification of delta 13CO2 prior to treatment is not useful to predict the success or failure of eradicating therapy.

13C-urea breath test in the management of Helicobacterpylori infection

The urea breath test is a noninvasive and very accurate test for the diagnosis of Helicobacter pylori infection. However, false negative urea breath test results have been reported to occur in a considerable percentage of the individuals taking proton pump inhibitors; the interval needed to be completely confident that false negative tests had been excluded has varied among the different studies between 6 and 14 days. The impact of H(2)-receptor antagonists on the accuracy of urea breath test remains controversial, although, in contrast with proton pump inhibitors, the data suggest that H(2)-receptor antagonists, for the most part, have little effect on the result of the urea breath test. The urea breath test does not represent a suitable tool for estimating the density of H. pylori colonization. The only quantitative information to be obtained from the urea breath test is that the higher the delta value, the lower the probability of a false-positive urea breath test result. Although some authors have demonstrated a correlation between urea breath test values and histological lesions of the gastric mucosa, the practical utility of this relationship remains unclear. It has been suggested that the pretreatment urea breath test has the potential to identify patients who require modification of the standard therapeutic regimen (for example, prolonging the duration of treatment or increasing the pharmacological dose when bacterial density is high), but other studies could not confirm this relationship. Some studies have shown that the urea breath test is less accurate in patients who have undergone partial gastrectomy. Finally, in contrast with biopsy-based methods, which are responsible for a high number of false-negative results when used to diagnose H. pylori infection in patients with upper gastrointestinal bleeding, urea breath test seems not to be negatively influenced by the presence of this complication.

Review article: 13C-urea breath test in the diagnosis of Helicobacter pylori infection -- a critical review

The urea breath test is a non-invasive, simple and safe test which provides excellent accuracy both for the initial diagnosis of Helicobacter pylori infection and for the confirmation of its eradication after treatment. Some studies have found no differences between urea breath test performed under non-fasting conditions. The simplicity, good tolerance and economy of the citric acid test meal probably make its systematic use advisable. The urea breath test protocol may be performed with relatively low doses (<100 mg) of urea: 75 mg or even 50 mg seem to be sufficient. With the most widely used protocol (with citric acid and 75 mg of urea), excellent accuracy is obtained when breath samples are collected as early as 10-15 min after urea ingestion. A unique and generally proposed cut-off level is not possible because it has to be adapted to different factors, such as the test meal, the dose and type of urea, or the pre-/post-treatment setting. Fortunately, because positive and negative urea breath test results tend to cluster outside of the range between 2 and 5 per thousand, a change in cut-off value within this range would be expected to have little effect on clinical accuracy of the test.

Breath sample collection through the nostril reduces false-positive results of 13C-urea breath test for the diagnosis of helicobacter pylori infection

BACKGROUND

One of the disadvantages of '3C-urea breath test is possible interference by urease activity not related to Helicobacterpylori.

AIMS

We design the simple and non-invasive modification to avoid the contamination of 13CO(2) produced in the mouth.

PATIENTS AND METHODS

One hundred and twenty-nine patients who underwent diagnostic upper endoscopy were enrolled. Within 1 week of the endoscopic procedure, each patient received the modified 13C-urea breath test. Breath samples were collected at baseline and at 1, 3, 5, 10, 15, 20 and 30 min after ingestion of 100 mg 13C-urea solution through the mouth and the nostril at each time point.

RESULTS

The breath delta13CO2 value through the nostril at 1 min was already higher in H. pylori-positive patients than in H. pylori-negative patients. Using 2.5% as the cut-off value, the sensitivity and specificity of the modified 13C-urea breath test at 20 min were both 100%, whereas the sensitivity and specificity of the standard 13C-urea breath test were 97.7 and 94%, respectively, using 3% as the cut-off value.

CONCLUSIONS

The modified 13C-urea breath test in which breath samples are collected through the nostril provides an easy way of avoiding false-positive results for the detection of H. pylori infection.

Is there an advantage in normalising the results of the Helicobacter pylori [13C]urea breath test for CO2 production rate in children?

The urea breath test (UBT) is a non-invasive diagnostic test to detect the presence of Helicobacter pylori in the stomach, and is the simplest way to confirm eradication after treatment. The test is based on the capacity of H. pylori to secrete the enzyme urease, which hydrolyses urea to ammonia and carbon dioxide. The aim of this study was to determine whether there is an advantage in expressing the results of UBTs in terms of urea hydrolysis rate (UHR), rather than breath 13C enrichment alone. Retrospective analysis of data collected between 1995 and 2002 from 260 patients undergoing UBTs was performed. The cut-offs for positive tests using breath 30-minute enrichment (E30), UHR calculated using VCO2 estimated from height and weight (H/WT) and VCO2 estimated from weight only were determined using two-graph receiver operator characteristic (TG-ROC) analysis. The cut-off points were 3.5/1000 or 38.7 ppm 13C excess, 7.04 micromol/h and 7.08 micromol/h, respectively. There was no advantage in expressing the results as UHR (theta0, Theta-zero, where sensitivity = specificity = 0.97 (UHR H/WT), 0.98 (UHR WT) and 1.00 (E30)) rather than breath 13CO2 enrichment alone. Differences in the extent of H. pylori colonisation and urease activity are more important than variation in VCO2 in determining breath 13CO2 enrichment in the UBT.

Simplified 13C-urea breath test with a new infrared spectrometer for diagnosis of Helicobacter pylori infection

BACKGROUND AND AIM

Infrared spectrometry has correlated excellently with mass spectrometry in detecting the ratio of 13CO(2) to 12CO(2) in breath samples. The present study aimed to evaluate the accuracy of the 13C-urea breath test (13C-UBT) using a new model of infrared analyzer.

METHODS

A total of 600 patients who were undergoing upper endoscopy without receiving eradication therapy were entered into the study. Culture, histology, and rapid urease test on biopsies from the antrum and corpus of the stomach were used for the determination of Helicobacter pylori infection. Breath samples were collected before and 20 min after drinking 100 mg 13C-urea in 100 mL water. The optimal cutoff value was determined by the receiver operating characteristic curve.

RESULTS

Of the 586 patients who were eligible for analysis, 369 were positive for H. pylori infection, 185 were negative for H. pylori infection, and 32 were indeterminate. When the appropriate cutoff value was set at 3.5 per thousand, a sensitivity of 97.8%, a specificity of 96.8% and an accuracy of 97.5% were obtained using the 13C-UBT. The accuracy of the 13C-UBT decreased when CO(2) concentration in the breath sample was <2%, as compared with > or = 2% (93.6%vs 97.7%), mainly because of a decrease in specificity (81.8%vs 97.7%). There were 2.7% of patients with Delta13CO(2) values that fell between 3.0-4.5 per thousand, in whom the risk of error was 47%.

CONCLUSIONS

The 13C-UBT performed with infrared spectrometry is a highly sensitive, specific, and non-invasive method for the detection of H. pylori infection. The immediate availability of the test result and technical simplicity make it particularly effective in routine clinical practice.

Five minute endoscopic urea breath test with 25 mg of (13)C-urea in the management of Helicobacter pylori infection

OBJECTIVE

The endoscopic (13)C-urea breath test ((13)C-EUBT), which combines the urea breath test (UBT) with endoscopy, provides high accuracy for the detection of Helicobacter pylori. This study was conducted to determine whether the (13)C-EUBT using low doses of urea and short sampling times could preserve accuracy in the management of H. pylori infection.

METHODS

Three hundred and twenty-five patients were randomized to receive the EUBT with 100, 50 or 25 mg of (13)C-urea by endoscopic spraying. The breath samples collected at 5, 10 and 20 min were analysed using an isotope selected non-dispersive infrared spectrometer. H. pylori infection was assessed by the rapid urease test and histology. In each sampling schedule and protocol, cut-off values were calculated by a receiver operating characteristic curve. We applied the EUBT with 25 mg of (13)C-urea at 5 min to the assessment of eradication in 135 patients who had received the antimicrobial treatment or to the detection of the organism in 61 patients with previous partial gastrectomy.

RESULTS

Based on histology and the urease test, patients who had discordant results were excluded from the analysis. Using 100 mg of urea, the sensitivity and specificity of the test were both 100% at 10 and 20 min, and the sensitivity and specificity at 5 min were best with 98.6% and 100%, respectively. With 50 mg, they were both 100% at 20 min, and the best combination of sensitivity and specificity at 5 and 10 min was 97.3-96.6% and 97.3-100%, respectively. Even with 25 mg, the sensitivity and specificity were both 100.0% at 20 min, and at the 5 min and 10 min time point, the EUBT yielded a sensitivity of 98.7% and a specificity of 100%. There was a significant positive correlation between the test values of the 5 min (13)C-EUBT with 25 mg of test urea and those of the conventional UBT. The 5 min EUBT with (13)C-urea offered high accuracy in the assessment of H. pylori eradication, with the sensitivity and specificity being 100% and 96.4%, respectively. In patients with previous gastrectomy, the EUBT provided acceptable accuracy (a sensitivity of 96.4% and a specificity of 97.0%).

CONCLUSIONS

Our results indicate that the (13)C-EUBT is an accurate method for detecting H. pylori infection. The EUBT using only 25 mg of (13)C-urea at the early (5 min) time point has satisfactory diagnostic efficacy in pre- and post-eradication treatment settings, providing a less expensive and more rapid way of performing the test. The EUBT may be a reliable method of assessing H. pylori status in the remnant stomach.

[13C]-urea breath test without prior fasting and without test meal is accurate for the detection of Helicobacter pylori infection in Chinese

BACKGROUND AND AIM

Conventional [13C]-urea breath test ([13C]-UBT) requires prior fasting and a test meal, which theoretically improves the accuracy of the test. However, recent studies have suggested that prior fasting and test meal may not be essential. We aimed to determine the accuracy of a new [13C]-UBT protocol without fasting in Chinese.

METHODS

Dyspeptic patients referred for upper endoscopy were recruited. The gold standard for Helicobacter pylori infection was the combination of Campylobacter-like organism (CLO) test and histology. Group I (n = 213) patients underwent [13C]-UBT with prior fasting and with citrate acid test meal. Group II (n = 123) patients underwent [13C]-UBT without prior fasting but with test meal. Group III (n = 90) patients underwent [13C]-UBT without prior fasting and without test meal.

RESULTS

The highest accuracy for groups I, II and III was 96.7, 95.1 and 95.5% using a cut-off value of 5.0, 5.5 and 3.5, respectively. The sensitivities and specificities were 97.4 and 95.8% in group I, 93.3 and 96.8% in group II, and 96.5 and 93.9% in group III, respectively.

CONCLUSION

The [13C]-UBT protocols without prior fasting and either with or without test meal produce highly accurate and reliable results in the Chinese population.

Diagnostic accuracy of the 13C-urea breath test for childhood Helicobacter pylori infection: a multicenter Japanese study

OBJECTIVES

In adults, the 13C-urea breath test (UBT) has been widely used as a noninvasive test of Helicobacter pylori infection because of its high sensitivity and specificity. However, this test is less well established in pediatric practice. The optimum cutoff value and test protocol of the 13C-UBT remains to be established in the pediatric population. The primary purpose of this study was to evaluate diagnostic accuracy of the 13C-UBT for children and to determine its optimum cutoff value.

METHODS

A total of 220 Japanese children aged 2-16 yr (mean = 11.9) who underwent upper GI endoscopy and gastric biopsies were finally studied. Endoscopic diagnoses included gastritis (n = 131), gastric ulcer (n = 15), duodenal ulcer (n = 72), and combined ulcer (n = 2). H. pylori infection status was confirmed by biopsy tests including histology, urease test, and culture. With the 13C-UBT, breath samples were obtained at baseline and at 20 min after ingestion of 13C-urea without a test meal and were analyzed by isotope ratio mass spectrometry. Based on biopsy tests, a cutoff value was determined using a receiver operating characteristic curve. In 26 children (seven children infected and 19 noninfected), paired breath samples were also measured by nondispersive infrared spectometry (NDIRS).

RESULTS

Biopsy tests demonstrated that 89 children (40%) were infected with H. pylori and 131 children were not infected. There were no statistical differences in mean delta 13C values at 20 min between male and female H. pylori-infected and noninfected patients. A receiver operating characteristic analysis defined the best cutoff value as 3.5 per thousand. The overall sensitivity and specificity at a cutoff value of 3.5 per thousand were 97.8% (95% CI = 92.1-99.7%) and 98.5% (95% CI = 96.4-100%), respectively: high sensitivity and specificity were demonstrated in all three age groups (< or =5, 6-10, and > or = 11 yr). There was a close correlation between the values with isotope ratio mass spectrometry and NDIRS methods (r = 0.998, p < 0.001).

CONCLUSIONS

The 13C-UBT with a cutoff value of 3.5 per thousand is an accurate diagnostic method for active H. pylori infection. The test with the NDIRS method is inexpensive and might be widely applied in clinical practice.

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.

13C breath tests: visions and realities

Breath tests have been used in research laboratories for over 25 y. Originally, the tests were based on the use of (14)C, rather than on the nonradioactive isotope, (13)C. When (13)C became widely available at a reasonable cost, research groups in the United States and Europe developed methodologies to measure (13)C abundance in samples of CO(2). The tests used a variety of substrates and measured pancreatic function, fat absorption, bacterial overgrowth and P(450) mixed-function oxidase. Thus far, the only test to be approved by the Food and Drug Administration is the (13)C-urea breath test. This manuscript describes the process by which approval is gained, and indicates the steps necessary for other tests to receive Food and Drug Administration approval.

Accurate diagnosis of Helicobacter pylori. 13C-urea breath test

The preferred schema for management of Helicobacter pylori infection is diagnosis, treatment, and confirmation of cure. The 13C-urea breath test is ideal for active H. pylori infection for those in whom endoscopy is not required (e.g., those in whom cancer is not suspected) because it offers the combination of simplicity, accuracy, reliability, and absence of exposure to radioactivity. New versions of the test also offer increasing simplicity and lower costs.

(13)C-urea breath test without a test meal is highly accurate for the detection of Helicobacter pylori infection in Chinese

BACKGROUND

Conventional (13)C-urea breath testing ((13)C-UBT) includes a test meal to delay gastric emptying, which, theoretically, improves the accuracy of the test. Citric acid has been proposed as the best test meal. However, recent studies have suggested that a test meal may not be necessary.

AIM

To investigate a new (13)C-UBT protocol without a test meal in a Chinese population.

METHODS

Consecutive dyspeptic patients referred for upper endoscopy were recruited. (13)C-UBT was performed on two separate days with or without a test meal (2.4 Gm citric acid) and compared with the 'gold standard' (CLO test and histology).

RESULTS

Two hundred and two patients were tested. Using receiver operating characteristics (ROC) analysis, the optimal delta-value and optimal measurement interval for UBT were 5% and 30 min, respectively, both with or without a test meal. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of (13)C-UBT with citric acid (96.5%, 97.7%, 98.2%, 95.6%, 97.0%) were similar to (13)C-UBT without a test meal (94.7%, 97.7%, 98.2%, 93.5%, 96.0%).

CONCLUSION

This simplified (13)C-UBT protocol without a test meal produced highly accurate and reliable results in the Chinese population.

13C urea breath test with nondispersive isotope-selective infrared spectrometry: reproducibility and importance of the fasting status

BACKGROUND

The 13C urea breath test (13C-UBT) is the most convenient method for diagnosing Helicobacter pylori infection noninvasively. Nondispersive isotope-selective infrared spectrometry (NDIRS) is an inexpensive and easy alternative to mass spectrometry. The objective of this study was to evaluate: (1) the reproducibility of the 13C-UBT as performed by using the NDIRS method; (2) the repeatability of bags analysis and the impact of delayed analysis; and (3) the need for fasting status for the 13C-UBT.

METHODS

The 13C-UBT was performed with 75 mg urea labeled with 13C, with breath samples collected at times 0 and 30 minutes. Results are expressed as delta over baseline (0/00). Fifty-three patients underwent two successive 13C-UBTs with an interval of 48 to 72 hours. The 106 collected bags were randomly reanalyzed immediately or 72 hours later. In 26 volunteer subjects, the 13C-UBT was performed both in a fasting condition and after a nonstandardized meal. The reproducibility was assessed by the method of Bland and Altman.

RESULTS

The mean of difference between two successive tests was 0. 14 0/00 (standard deviation, 0.90), and the coefficient of repeatability was 1.80 (confidence interval, 95%). The difference between two successive analyses was always less than 2.2% of the initial value. The coefficient of variation between two successive tests for the influence of a meal was 11.24.

CONCLUSION

The 13C-UBT as performed by using NDIRS is reproducible, analyses can be delayed up to 72 hours, and the test must be performed in fasting conditions.

Carbon urea breath test is not as accurate as endoscopy to detect Helicobacter pylori after gastrectomy

BACKGROUND

This study was conducted to determine (1) whether Helicobacter pylori infection decreases in conjunction with time elapsed after gastrectomy and (2) the diagnostic efficacy of (13)C urea breath test (UBT) for H pylori in patients after gastrectomy.

METHODS

From January 1997 to June 1998, 86 patients who had undergone gastrectomy and 180 patients with dyspepsia without gastrectomy were enrolled. A UBT for the analysis of excess (13)CO(2)/(12)CO(2) ratio (ECR) was obtained for each patient. Each patient also underwent endoscopy to obtain gastric biopsies for histology and H pylori culture. The presence of H pylori by either histology or culture served as the standard to test the efficacy of UBT. The 86 patients with a prior gastrectomy were categorized into 3 subgroups (I, less than 1 year; II, 1 to 3 years; III, greater than 3 years), according to the interval between surgery and UBT. The initial H pylori status of these 86 patients was determined by histologic evaluation of the resected stomach.

RESULTS

At trial initiation, the postgastrectomy group had a lower H pylori infection rate (52.3%) as compared with the dyspeptic control group (80%). The initial H pylori status among subgroups I, II, and III was similar. There was a trend for the presence of H pylori in the stomach to decrease with increasing time elapsed after surgery (I to III: 68.8%, 48.3%, 36%, respectively; p < 0.05). The maximum UBT sensitivity and specificity achieved were 82.2% and 87.8% in the gastrectomy group and 97.2% and 96.3% in the dyspeptic group, with cutoff points of 2.5 and 4.0, respectively.

CONCLUSION

The prevalence of H pylori diminishes with time elapsed after gastrectomy. UBT for detection of H pylori is more effective in patients without prior gastrectomy than in patients who have undergone gastrectomy and is less effective than endoscopy for patients who have had a gastrectomy.

Modified rapid urease test for Helicobacter pylori detection in relation to an immunohistochemical stain

BACKGROUND

The rapid urease test and touch cytology have been used for the rapid detection of Helicobacter pylori infection. Recently, a modified rapid urease (MRU) test, which provides results in 20 min has been available on a commercial basis. To date, few reports have evaluated the accuracy of this test. This study evaluated the sensitivity, specificity, and accuracy of the MRU test and touch cytology to detect H. pylori in relation to the density of H. pylori infection determined semi-quantitatively by using immunohistochemical stains.

METHODS

Biopsy specimens obtained from a total of 60 patients who underwent endoscopy for evaluation of gastroduodenal diseases were studied by using the MRU test, Giemsa stain for touch smear tissue and histological methods. An immunohistochemical stain was used as a standard, and the density of H. pylori infection was graded according to the number of individual bacteria seen as follows: grade 0 = 0; grade 1+ = 1-9; grade 2+ = 10-29; grade 3+ = 30-99; grade 4+ > or = 100. The severity of gastritis was evaluated histologically in each specimen and compared with the density of H. pylori infection.

RESULTS

The MRU test had an overall sensitivity of 73%, specificity of 100% and accuracy of 85%. The Giemsa stain had a sensitivity of 91%, specificity of 100% and accuracy of 95%.The sensitivities of the MRU test and Giemsa stain decreased in mild H. pylori infection. In the MRU test, the sensitivity was 47% when the density of H. pylori infection was 1+, while 80-100% sensitivities were obtained when the densities of infection were > or = 2+. With the Giemsa stain, the sensitivity was 80% when the density was 1+, while the sensitivity increased to 100% when the densities were > or = 2+. The severity of gastritis determined by the Rauws scores showed a positive correlation with the density of H. pylori infection as evaluated by immunohistochemical staining.

CONCLUSIONS

The MRU test had high sensitivity and specificity for moderate to severe H. pylori infection, but it may result in false-negative results in tests for mild infection. As the MRU test has the advantages of shorter incubation times and low cost, a combination of the MRU test and the Giemsa stain for touch cytology may be the most time- and cost-efficient tests in a clinical setting for the diagnosis of H. pylori infection.

Endoscopic [13C]-urea breath test for quantification of Helicobacter pylori infection

BACKGROUND

We previously developed a new diagnostic method for Helicobacter pylori infection and called it the endoscopic [13C]-urea breath test (EUBT). Here we evaluate the relationship between the EUBT results and the histological findings.

METHODS

The EUBT was performed on 137 patients with gastroduodenal diseases. After the collection of a baseline breath sample, gastroduodenal endoscopy was performed. Twenty milliliters of 0.05% phenol red solution containing 100 mg of [13C]-urea was sprayed over the entire gastric mucosa under endoscopic observation. A breath sample was collected 15 min after spraying. The content of 13CO2 in the breath samples was measured by ratio mass spectrometry. Two biopsy specimens each from the antrum and the middle corpus were obtained for culture and histology. Helicobacter pylori colonization, activity, inflammation, atrophy and intestinal metaplasia were classified on a four-point scale according to the Updated Sydney System.

RESULTS

We found positive correlations between the EUBT values and the H. pylori colonization and activity score in the antrum and corpus, and negative correlations between the EUBT values and the atrophy and intestinal metaplasia scores in the corpus.

CONCLUSIONS

The EUBT can be an indicator of the intragastric bacterial load and the histological findings for H. pylori.

Influence of age on 13C-urea breath test results in children

BACKGROUND

The 13C-urea breath test for diagnosis of Helicobacter pylori infection has not been validated in infants and young children. The influence of age on the test results was studied by conventional validation against invasive methods and by mathematical estimation in a large pediatric population.

METHODS

The breath test was performed in 1499 children aged 2 months to 18 years. After a fasting period of 4 hours or more, 75 mg 13C-urea was ingested with cold apple juice, breath samples were taken at baseline and at 15 and 30 minutes. The distribution of the natural logarithms of the delta-over baseline (DOB) values were calculated, and the optimal cutoff values between positive and negative test results and gray zones with a risk of misclassification more than 10% were determined for both time points. In a subgroup of 149 children results of the breath test were compared with concordant results of histology and rapid urease test; 53 of them were less than 6 years of age.

RESULTS

Logarithmic results of 1499 breath tests revealed two normally distributed subgroups with minimal overlap. The calculated optimal cutoff values were 4.7/1000 at 15 minutes and 5.0/1000 at 30 minutes. At 30 minutes, only 2.6% of all results were in the calculated gray zone (2.6-6.5/1000). Age was negatively correlated to DOB values of both negative (r = -0.223) and positive results (r = -0.291; P < 0.001). Breath test-negative and -positive children 6 or less years of age had significantly higher mean DOB values (P < 0.02) and a larger proportion of results within the gray zone than older children. Compared with biopsy-based results, the least discrepancies occurred at a cutoff of 5.0/1000: 0 of 61 infected (sensitivity 100%) and 6 of 88 noninfected children. Because five of the false-positive results were obtained in children less than 6 years of age, specificity and positive predictive values were lower in this age group than in older patients (88.1% vs. 97.8% and 68.8% vs. 98.0%, respectively).

CONCLUSIONS

Under the applied conditions, the 13C-urea breath test shows an excellent separation between positive and negative results. Because of some overlap and a strong age effect, definition of a gray zone appears more meaningful than a threshold value. Because infants and young children have a high risk for false-positive breath test results, the values for cutoff and gray zones may have to be adapted. Further validation studies against invasive methods are warranted in this age group.

13C-urea breath test for the diagnosis of Helicobacter pylori infection before treatment: is citric acid necessary?

AIM

13C-urea breath test is one of the best methods for the diagnosis of Helicobacter pylori infection. Although a citric acid solution is generally used prior to urea intake, the superiority of this strategy has not been sufficiently demonstrated. Thus, our aim was to compare 13C-urea breath test with and without citric acid solution, to evaluate whether 13C-urea breath test can also achieve favourable results when the test meal is omitted.

METHODS

13C-urea breath test with and without citric acid were compared prospectively in 53 subjects without prior Helicobacter pylori eradication therapy prescription. Basal samples and at 15', 30', and 45' after taking 100 mg of 13C-urea were obtained. The gold standard for Helicobacter pylori diagnosis was the 13C-urea breath test result with citric acid at 30', and "Delta Over Baseline" values >5 at that time were considered positive.

RESULTS

The prevalence of Helicobacter pylori infection was 68%. Mean Delta Over Baseline values with citric acid at 15', 30' and 45' were: 29.6+/-39, 30.8+/-37 and 24.6+/-27; whereas respective values without citric acid were lower: 14.9+/-22, 12.2+/-17 and 10D+/-13 (p<O. 001 for all comparisons, Wilcoxon test for paired data). Thus, the area under the curve (constructed with Delta Over Baseline values at different times) with citric acid was 85+/- 102, and 37+/-50 without citric acid [p<0.001). Correlation coefficient between Delta Over Baseline values with and without citric acid at 30' was 0.73 (p<0.0001). The percentage of subjects achieving the highest Delta Over Baseline value at 15', 30' and 45' with citric acid was 51%, 30% and 19%, whereas without citric acid it was 51%, 26% and 23% (non-significant differences). The area under receiver operating characteristic curve for 13C-urea breath test without citric acid was: 0.98 at 15', 1 at 30' and 0.97 at 45'. The best cut-off point for 13C-urea breath test without citric acid at 30' was anywhere between 3. 3 and 3.9 (that is, a lower value than that usually considered with citric acid), with 100% (95% confidence interval, 90-100%) sensitivity and 100% [82-100%) specificity

CONCLUSIONS

13C-urea breath test values with citric acid are higher than those obtained without citric acid, although this difference does not imply a diagnostic superiority in untreated patients when considering 13C-urea breath test without citric acid at 30'. Therefore, for the diagnosis of Helicobacter pylori infection in untreated patients, citric acid solution in 13C-urea breath test protocol can be omitted.

Helicobacter pylori: optimum diagnosis and test of cure

The fact that about 50% of the world's population is infected with Helicobacter (H.) pylori and the important role that this bacterium plays in public health have been important incentives in the search for accurate diagnostic methods. A large number of invasive and non-invasive methods have been used to diagnose H. pylori infection. Each method has its advantages and disadvantages and each practitioner should choose the best diagnostic method according to the facilities available. Non-invasive tests for the diagnosis of H. pylori infection are largely used in clinical practice and in management of patients with gastroduodenal disease. Serology is the most widespread test but its use is not advised in the post-treatment follow-up. The Urea Breath Test is a simple, safe and highly accurate method ideal for evaluating the short-term follow-up of H. pylori eradication after therapy.

Citric acid or orange juice for the 13C-urea breath test: the impact of pH and gastric emptying

BACKGROUND

There is an ongoing debate about the optimal test drink to be used in the 13C-urea breath test (13C-UBT). We recently reported that a citric acid solution is the optimal test drink in the 13C-UBT, because it provides a high 13CO2 recovery and the excellent accuracy of the test appears optimal compared to other test meals. Orange juice, because of a better taste, is also propagated as a test drink in the 13C-UBT.

AIM

To compare the diagnostic accuracy of the 13C-UBT with either orange juice or citric acid solution as a test drink. Furthermore, the effect of these test drinks on the gastric emptying rate was determined.

METHODS

H. pylori status was assessed by histology, rapid urease test and culture in 50 consecutive dyspeptic patients. A 13C-UBT was performed on two consecutive days by giving 75 mg of 13C-urea randomly dissolved in 200 mL 0.1 M citric acid solution or 200 mL orange juice. The 13CO2/12CO2 ratio was measured in breath samples taken before and 15, 30, 45 and 60 min after administration of the test drink. The gastric emptying rate of orange juice and citric acid solution was compared to that of water in 10 healthy subjects on three consecutive days by means of a 13C-sodium acetate breath test; 50 mg of 13C-sodium acetate was dissolved in 200 mL of each solution and breath samples were collected before and every 10 min for 90 min after administration of the test drink.

RESULTS

Twenty-six out of 50 patients (52%) were infected with H. pylori. Significantly higher values over baseline (35.7+/-5.2 per thousand vs. 23.2+/-3.4 per thousand, P<0.001) and higher area under the curve (1507+/-198 vs. 927+/-128, P<0.001) were observed in H. pylori-positive patients when citric acid solution was administered compared with orange juice. Sensitivity of the 13C-UBT was 100% when citric acid was used as a test drink and 88% with orange juice. Specificity was 100% with both test drinks. Gastric emptying of citric acid solution (t1/2 = 60.9+/-3.5 min) was significantly slower than that of orange juice (t1/2 = 49.7+/-3.1 min, P<0.001).

CONCLUSION

13C-UBT loses diagnostic accuracy when orange juice instead of citric acid is used as a test drink. The faster gastric emptying of orange juice might be responsible for the lower diagnostic accuracy of the 13C-UBT.

Citric acid as the test meal for the 13C-urea breath test

OBJECTIVE

Test meals are used in the urea breath test to slow gastric emptying and to increase the area of contact with the substrate. Recently, citric acid has been suggested as an improved liquid test meal. The mechanism is unknown and could act by delaying gastric emptying, decreasing the pH at the site of the bacteria, or both. Our aim was to evaluate the effects of citric acid test meals on urea hydrolysis in vivo, to identify the possible mechanism for enhanced urea hydrolysis, and to identify the minimum effective dose.

METHODS

We compared the U.S. commercial 13C-urea breath test with four liquid test meals (200 ml of water) consisting of citric acid, ascorbic acid, sodium citrate, and glucose polymer and also after the subcutaneous administration of pentagastrin. We studied healthy volunteers with and without proven H. pylori infection (by serology and histology). 13C-urea was administered orally simultaneously with the liquid test meals or immediately after the pudding had been ingested. Breath samples were taken before and after oral administration of the 13C-urea.

RESULTS

A dose response in urease activity was evident as the amount of citric acid was increased from 1 to 4 g. Citric acid at 1, 2, or 4 g produced significant increases in breath 13CO2 activity, compared with the commercial pudding (p < 0.05). Ascorbic acid (p = 0.053), subcutaneous pentagastrin (to lower pH) (p = 0.199), and glucose polymer (p = 0.03) (to delay gastric emptying) all approximately doubled breath 13CO2, compared with the commercial kit. Nevertheless, the increases were all significantly less than with the 4 g citric acid test meal.

CONCLUSIONS

The data are consistent with the marked effect of citric acid on gastric emptying and, possibly, distribution of the urea within the stomach being largely responsible for the enhanced urease activity with citric acid test meals. It should be possible to use a low dose of citric acid (e.g., 1 g per 200 ml) to enhance the simplicity and palatability of the test.

The impact of delaying gastric emptying by either meal substrate or drug on the [13C]-urea breath test

OBJECTIVE

Optimal [13C]-urea breath test (UBT) conditions for diagnosis of Helicobacter pylori infection are still being fine-tuned. In the present study we investigated the impact of delaying gastric emptying by different meal substrates or L-DOPA, a drug known to induce gastric stasis, on the performance of the [13C]-UBT.

METHODS

A total of 115 patients participated in the study. On two consecutive days, participants ingested [13C]-urea (100 mg) 10 min after either 270 ml of a mixed formula meal (1 Kcal/ml) or an equivalent amount of tap water. In 11 participants two additional tests were performed with or without oral 500 mg L-DOPA given 30 min before [13C]-urea load. The 13C/12C ratio in a basal breath sample was compared with ratios in samples collected 30 and 60 min after [13C]-urea. Histological assessment of H. pylori presence in antral biopsy served as reference standard.

RESULTS

Formula UBT showed excellent specificity (100% at 30 and 60 min) and good sensitivity (97% at both time intervals), whereas water UBT had the same specificity but slightly lower sensitivity (94% at 30 min and 73% at 60 min). In formula UBT, 13C/12C ratios were higher at 60 min than at 30 min (21.7+/-2 vs 17.7+/-1.8 per thousand respectively, p < 0.01, whereas in water UBT 13C/12C ratios were higher at 30 min than at 60 min (13.9+/-1.5 vs 8.4+/-0.09 per thousand respectively, p < 0.01). Pretreatment with L-DOPA did not modify either the sensitivity or the specificity of the UBT.

CONCLUSIONS

The performance of the [13C]-urea with a formula meal may not be improved by pharmacologically delaying gastric emptying. A short, water-based test may be a sensible approach to worldwide standardization of the [13C]-UBT for H. pylori infection.

[The 13C-urea breath test in Helicobacter pylori gastric infection in children]

Helicobacter pylori gastric infection in children is a public health problem. Classical diagnostic tools such as endoscopy are excessively invasive in the usual clinical context. Serology at this age has multiple drawbacks. The urea-13C breath test seems today the most appropriate alternative method. The principle of the test relies upon the indirect detection of H pylori through its high urease activity. The test uses a stable (ie, non radioactive) isotope, which allows its repeated use. The main indications are the detection and the follow-up of H pylori infection.

Usefulness of the [13C]-urea breath test for detection of Helicobacter pylori infection in fasting patients

Most of the reported [13C]-urea breath test procedures use a test meal, which is believed to assist in the spread of the [13C]-urea solution into the entire stomach, as results without a test meal may mainly reflect urease activity in the antrum.Yet, procedures for the [13C]-urea breath test and interpretation of the obtained 13C excess value have not been well established. We carried out the present study to validate the usefulness of the [13C]-urea breath test in fasting subjects and to establish cut-off values. [13C]-Urea breath tests were performed on 258 Helicobacter pylori-positive and 151 -negative subjects (247 H. pylori positive and 26 negative prior to any H. pylori cure treatment and 125 H. pylori negative and 11 positive after undergoing H. pylori cure treatment). The breath test procedure was performed under the following conditions: an 8 h fast, mouth washing before and after dosing, administration of 100 mg [13C]-urea, collection of breath sample in a plastic bag, a baseline and a 20 min sampling point and subject in a sitting position. Delta-13C at the 20 min sampling point in H. pylori-positive and -negative subjects was 31.0+/-1.25 and 1.6+/-0.11%, respectively. Although the mean delta13C value was greatest in duodenal ulcer or ulcer scar patients, there were no significant differences among mean delta13C values in the various diseases. From Receiver Operator Characteristic curves and calculation of accuracy of the test, a cut-off value of 5.0% is considered to be appropriate for diagnosis of H. pylori infection, which provides 96.7% specificity and 96.5% sensitivity, suggesting that the [13C]-urea breath test in the fasting state is as effective in detecting the presence of H. pylori as other reported methods.

Variation in the 13C-urea breath test value by nationality in Helicobacter pylori-infected children

BACKGROUND

The 13C-urea breath (13C-UBT) test value is (semi-)quantitatively related to Helicobacter pylori density in the gastric antrum, and the value correlates with the grade of gastritis. The aim of this study was to assess variation of the 13C-urea breath test value by sociodemographic factors in H. pylori-positive children.

METHODS

The analysis was performed on 127 asymptomatic children (aged 5-7 years) who were identified as H. pylori-positive with the 13C-UBT test in a large population-based epidemiologic study in the city of Ulm (southern Germany). The parents of the children were asked to fill out a standardized questionnaire about sociodemographic data.

RESULTS

Forty-two infected children (33.1%) were of German nationality, 47 children (37.0%) were of Turkish and 38 children (29.9%) were of another nationality. Turkish children had a significantly higher 13C-UBT value (geometric mean = 27.2%) than German children (16.7%) or children with another nationality (19.3%) (P < 0.001). Girls had a trend towards higher values than boys (P = 0.058 after adjustment for nationality). Body mass index, education of the parents, and prior use of antibiotics were unrelated to the extent of the 13C-UBT.

CONCLUSIONS

This study identified significant variation in the extent of the 13C value by nationality among H. pylori-infected children. Further studies are needed to elucidate the causes and potential consequences of these variations.

Analysis of risk factors for chronic hepatic encephalopathy: the role of Helicobacter pylori infection

OBJECTIVE

Elevated blood ammonia is an important pathogenic factor of hepatic encephalopathy. Although colonic bacteria are considered the main source of ammonia, the stomach in subjects with urease-producing Helicobacter pylori (H. pylori) is an alternative site. The objective of this study was to determine whether H. pylori is associated with this complication.

METHODS

After assessing liver function and portal hypertension, 55 cirrhotics were evaluated for encephalopathy and H. pylori infection. Response to 2 weeks of amoxicillin (2 g/day) and omeprazole (40 mg/day) was then assessed in 17 (13 H. pylori-positive, four H. pylori-negative) encephalopathic subjects.

RESULTS

H. pylori infection was more common (67 % vs 33%, p = 0.004) among encephalopathic patients. Additional factors associated with encephalopathy included older age (60.1 +/- 1.5 vs 49.8 +/- 2.4 yr, p = 0.001), lower albumin (3.17 +/- 0.08 vs 3.69 +/- 0.12 g/dl, p = 0.001), higher total bilirubin (2.24 +/- 0.20 vs 1.53 +/- 0.23 mg/dl, p = 0.034), greater ascites score (0.8 +/- 0.1 vs 0.3 +/- 0.1, p = 0.01), greater diuretic score (1.1 +/- 0.1 vs 0.3 +/- 0.1, p = 0.002), and greater modified Child score (6.7 +/- 0.3 vs 5.1 +/- 0.3, p = 0.001). When adjusted for severity of cirrhosis and age, H. pylori continued to demonstrate a statistical association (p = 0.039). After anti-H. pylori therapy, symptomatology in infected encephalopathic patients appeared to improve, whereas noninfected subjects were unaffected.

CONCLUSION

In cirrhotic patients, H. pylori infection is associated with hepatic encephalopathy, especially in younger patients with decompensated liver disease.

Semiquantitative evaluation for diagnosis of Helicobacter pylori infection in relation to histological changes

OBJECTIVES

Several methods are used to detect Helicobacter pylori (HP) infection. However, few reports have evaluated the accuracy of each method and compared the grade of HP infection with the severity of histological changes. HP infection was evaluated semiquantitatively in relation to the severity of gastritis, and the sensitivity, specificity, and accuracy of several methods to detect HP infection were compared.

METHODS

Biopsy specimens, obtained from a total of 64 patients who underwent endoscopy for evaluation of gastroduodenal diseases, were studied using a rapid urease test, culture, and histological assessment. An immunohistochemical method was used as the gold standard and graded according to the number of individual bacteria seen, as follows: 0 = 0; 1+ = <10; 2+ = 10-29; 3+ = 30-99; 4+ = >100. The severity of gastritis was evaluated histologically in each specimen and compared with the grade of HP infection.

RESULTS

The rapid urease test had a sensitivity of 53%, specificity of 100%, and accuracy of 73%. The culture method had a sensitivity of 75%, specificity of 100%, and accuracy of 86%. Sensitivities of the rapid urease test and the culture method decreased in a positive correlation with the decrease in total number of HP bacteria counted. Using the rapid urease test, sensitivity was <30% when the grade of HP infection was < or =2+, whereas 100% sensitivity was obtained when the grade of HP infection was 4+. On the other hand, sensitivity of the culture method remained between 80% and 90% when HP infection was > or =2+. The severity of gastritis determined with Rauws scores increased in a positive correlation with the grade of HP infection as evaluated by immunohistochemical stain.

CONCLUSIONS

The rapid urease test and culture of HP may result in false-negative tests for a mild infection, although they had high sensitivity and specificity for moderate to severe infection. Immunohistochemical stain provides a reliable semiquantitative diagnosis of HP infection and a positive correlation with histological changes. Clinicians should be aware of the characteristics of each method to detect HP infection and select the appropriate one(s) for their purposes.

Helicobacter pylori

Helicobacter pylori is a gram-negative bacterium which causes chronic gastritis and plays important roles in peptic ulcer disease, gastric carcinoma, and gastric lymphoma. H. pylori has been found in the stomachs of humans in all parts of the world. In developing countries, 70 to 90% of the population carries H. pylori. In developed countries, the prevalence of infection is lower. There appears to be no substantial reservoir of H. pylori aside from the human stomach. Transmission can occur by iatrogenic, fecal-oral, and oral-oral routes. H. pylori is able to colonize and persist in a unique biological niche within the gastric lumen. All fresh isolates of H. pylori express significant urease activity, which appears essential to the survival and pathogenesis of the bacterium. A variety of tests to diagnose H. pylori infection are now available. Histological examination of gastric tissue, culture, rapid urease testing, DNA probes, and PCR analysis, when used to test gastric tissue, all require endoscopy. In contrast, breath tests, serology, gastric juice PCR, and urinary excretion of [15N]ammonia are noninvasive tests that do not require endoscopy. In this review, we highlight advances in the detection of the presence of the organism and methods of differentiating among types of H. pylori, and we provide a background for appropriate chemotherapy of the infection.

Accurate detection of Helicobacter pylori infection with a simplified 13C urea breath test

The urea breath test (UBT) has been shown to be a reliable non-invasive method for detection of H. pylori infection. There is widespread use of a test meal in the 13C UBT, but to what extent exclusion of the test meal actually influences the accuracy of the test has been poorly investigated. In addition, there is variability between test protocols in breath sampling frequency. In this evaluation, 91 patients with dyspeptic symptoms were investigated in an out-patient endoscopy ward, using a simplified 13C UBT without a test meal, and a single point breath evaluation after ingestion of 13C-labelled urea. Helicobacter pylori infection was diagnosed on upper endoscopy by histology and rapid urease tests on biopsies from the antrum and corpus mucosa of the stomach. Fifty-four percent of the patients had H. pylori infection. With the chosen cut-off level, the sensitivity and specificity of the 13C UBT were 92% and 95%, respectively. We conclude that this simplified 13C UBT is easy to perform and a very reliable test for detecting H. pylori infection, making it a suitable test in routine clinical work.

Helicobacter pylori

Helicobacter pylori is a gram-negative bacterium which causes chronic gastritis and plays important roles in peptic ulcer disease, gastric carcinoma, and gastric lymphoma. H. pylori has been found in the stomachs of humans in all parts of the world. In developing countries, 70 to 90% of the population carries H. pylori. In developed countries, the prevalence of infection is lower. There appears to be no substantial reservoir of H. pylori aside from the human stomach. Transmission can occur by iatrogenic, fecal-oral, and oral-oral routes. H. pylori is able to colonize and persist in a unique biological niche within the gastric lumen. All fresh isolates of H. pylori express significant urease activity, which appears essential to the survival and pathogenesis of the bacterium. A variety of tests to diagnose H. pylori infection are now available. Histological examination of gastric tissue, culture, rapid urease testing, DNA probes, and PCR analysis, when used to test gastric tissue, all require endoscopy. In contrast, breath tests, serology, gastric juice PCR, and urinary excretion of [15N]ammonia are noninvasive tests that do not require endoscopy. In this review, we highlight advances in the detection of the presence of the organism and methods of differentiating among types of H. pylori, and we provide a background for appropriate chemotherapy of the infection.

MIN 14C UBT: a combination of gastric basal transit and 14C-urea breath test for the detection of Helicobacter pylori infection in human beings

The purpose of this work is to demonstrate that the 14C-urea breath test (UBT) performed at different times combined with the study of the gastric basal transit, which evaluates the intragastric displacement of a labeled solution under fasting conditions, has the advantage of being representative of the whole stomach surface and constitutes a non-aggressive test for the detection of H. pylori. This test, which has been called MIN 14C UBT, is a modification of the conventional 14C UBT in which low volumes of a solution of 14C-urea together with 99mTc-sulfur colloid are administered. The 99mTc-sulfur colloid is not absorbed in the gastrointestinal tract and has the great advantage of allowing the "visualization" of the transit of the 14C-urea within the gastrointestinal tract. This modification allows the simultaneous determination of the production of the 14CO2 and the place where this process occurs. The results show that there is a good correlation between the images obtained and the breath samples collected. We found that this test has a sensitivity of 98% and a specificity of 96% for H. pylori detection.

Effect of fasting subjects' posture on 13C-urea breath test for detection of Helicobacter pylori infection

BACKGROUND

Although many factors that may affect the 13C-urea value have been verified, no literature is available regarding the effect of the posture of the patient on the shape of the delta 13C excretion curve. In an effort to contribute to the development of a simple and standard procedure for the 13C-urea breath test, we investigated whether either the posture of the patient during the procedure or the mouthwash after dosing affects the shape of the delta 13C excretion curve.

MATERIALS AND METHODS

Seventy-two Helicobacter pylori-infected subjects were divided into four groups according to the position during procedure and the mouthwash after dosing: group A, in the supine position with mouthwash; group B, in the sitting position with mouthwash; group C, changed position by rolling with mouthwash; and group D, changed position (as did group C) without mouthwash. Absolute values of delta 13C at each sampling point were compared in the four groups.

RESULTS

delta 13C values in group A gradually increased until the 15-minute point; those in group B were almost stable from 5 to 30 minutes, and those in group C peaked at the 5-minute point, then decreased until 30 minutes, the values becoming similar at the 20-minute point. Significant differences were seen between groups A, B, C, and D at the 5- and 10-minute points.

CONCLUSION

These results suggest that posture and mouthwash affect delta 13C value at the 5- and 10-minute points. Sampling at 20 (maybe 15 or 30) minutes for fasting patients in a sitting position is considered to be appropriate for detection of H. pylori infection in a standard two-sampling-point 13C-urea breath test.

Gastric diffusion of antibiotics used against Helicobacter pylori

Only a few pharmacological studies have been carried out on men and guinea pigs to determine the gastric diffusion of antibiotics, which are active against Helicobacter pylori. The results of these studies have been analysed in considering the physicochemical nature, the mode of administration, the way of gastric diffusion (topic and/or systemic) and the pharmacological interactions. The correlation of these pharmacokinetic results with those obtained in clinical trials is difficult because of the heterogeneity of the pharmacological and pharmacodynamic data. The absence of a convenient and suitable animal or in vitro study model renders further standardized pharmacokinetic studies in infected man and at steady state necessary.