13C-urea breath test: reproducibility and association with the severity of Helicobacter pylori-associated antral gastritis

A prospective study on Helicobacter pylori rapid urease test false negativity: is it time for its use in restricted situations?

BACKGROUND

Rapid urease test (RUT) is a diagnostic tool for Helicobacter pylori (H. pylori) diagnosis, based on the ability of the bacterium to produce urease. Despite it is considered simple, fast, and cheap, some conditions may cause false negativity. Therefore, the aim of this study was to compare RUT with currently recommended tests for H. pylori diagnosis.

METHODS

We enrolled consecutive patients who underwent upper endoscopy with histology, RUT, and urea breath test (UBT). Delta over baseline (DOB) >4% was considered positive for UBT. Diagnosis of infection was achieved when at least two tests were positive. The rate of false positivity of RUT was computed, and DOB value in RUT+ versus RUT- was compared by Mann-Whitney Test.

RESULTS

One hundred and sixteen consecutive patients with H. pylori infection were recruited. The male/female ratio was 35/81 and the mean age 45.2±13.1. Twenty-five patients (21.5%) were RUT-, despite being positive at both histology and UBT. On the other hand, in only two patients UBT and histology had discordant results. A full concordance of the three tests was observed in 89 patients (76.7%). DOB, additionally, was significantly higher in RUT+ patients (39.2±24.2%) than RUT- ones (26.3±18.5%; P=0.005).

CONCLUSIONS

RUT shows false negativity rate higher than 20%. Moreover, the RUT-negative patients showed a lower DOB at UBT, which is an indirect indicator of intragastric bacterial load. Therefore, it is presumable that H. pylori low amount may be a concurrent cause of false negativity. This study suggests that RUT-based H. pylori detection should be restricted to some specific conditions.

The efficacy of Lactobacillus acidophilus and rhamnosus in the reduction of bacterial load of Helicobacter pylori and modification of gut microbiota-a double-blind, placebo-controlled, randomized trial

BACKGROUND

Probiotics may alter the gut microbiota and may reduce antibiotic-related dysbiosis after H. pylori eradication. However, whether probiotics are effective in reducing the bacterial load of H. pylori and modifying the gut microbiota remains unknown. We aimed to assess the efficacy of Lactobacillus acidophilus and Lactobacillus rhamnosus in reducing the bacterial load of H. pylori and modifying the gut microbiota.

MATERIALS AND METHODS

In this double-blind, randomized, placebo-controlled trial, we recruited 40 adult subjects with moderate to high bacterial loads of H. pylori, defined as a mean delta over baseline (DOB) value of the ¹³ C-urea breath test (¹³ C-UBT) of 10 or greater every 4 days 6 times. Eligible subjects were randomized in a 1:1 ratio to receive either probiotics containing Lactobacillus acidophilus and Lactobacillus rhamnosus or placebo twice daily for 4 weeks. ¹³ C-UBT was measured weekly from the beginning of treatment to 2 weeks after treatment. Amplification of the V3 and V4 hypervariable regions of the 16S rRNA was performed for fecal microbiota.

RESULTS

A total of 40 subjects were randomized to receive probiotics or placebo. The DOB value was significantly lower in the probiotic group than in the placebo group after 4 weeks of treatment (26.0 vs. 18.5, p = .045). The DOB value was significantly reduced compared to that at baseline in the probiotic group (18.5 vs. 26.7, p = .001) but not in the placebo group (26.0 vs. 25.0, p = .648). However, the eradication rate for H. pylori was 0% in both groups. There was no significant difference in the DOB values between the two groups 1 and 2 weeks after discontinuation of the probiotics. There were also no significant changes observed in the α-diversity and β-diversity at week 4 compared to baseline in the probiotic group (p = .77 and 0.91) and the placebo group (p = .26 and 0.67).

CONCLUSIONS

Although the use of Lactobacillus acidophilus and Lactobacillus rhamnosus may reduce the bacterial load of H. pylori, there were no significant changes in the composition of gut microbiota. This trial is registered with ClinicalTrials.gov, NCT02725138.

Association of cagA+ Helicobacter pylori strains with high urease activity and dyspepsia in Mexican adults

INTRODUCTION AND AIMS

Helicobacter pylori (H. pylori) is associated with a higher risk of peptic ulcer and gastric cancer. The sole presence of the bacterium is not a determinant of clinical outcome, but rather the interaction of strain type and host factors determines the risk of disease. Our aim was to study the association between bacterial load, strain type, and gastric symptoms in H. pylori-positive subjects.

MATERIALS AND METHODS

In a community survey, a diagnostic ¹³C-urea breath test for H. pylori was performed on 302 volunteers that were not taking antibiotics, antacids, or proton pump inhibitors one month prior to the test. The breath test produced 25 H. pylori-positive subjects, between 25-74 years of age, who then took a gastric symptoms survey and were tested for the presence of the cagA genotype in gastric juice, using the Entero-test®. Bacterial load was determined as a measure of urease activity, utilizing the delta over baseline value, obtained in the ¹³C-urea breath test.

RESULTS

A total of 48% of the H. pylori-positive subjects were cagA+. A positive association was found between cagA status and high gastric urease activity (P<.0001) and the latter was significantly associated with the presence of symptoms (P<.0001).

CONCLUSION

Gastric urease activity was strongly associated with dyspeptic symptoms and cagA+ H. pylori. Elevated ¹³C-delta over baseline values could be used as indicators of a higher risk for gastric disease.

Development of a 13C Stable Isotope Assay for Dipeptidyl Peptidase-4 Enzyme Activity A New Breath Test for Dipeptidyl Peptidase Activity

Dipeptidyl peptidase-4 inhibitors (DPP4i) are a class of orally available, small molecule inhibitors for the management of Type-II diabetes. A rapid, real-time, functional breath test for DPP4 enzyme activity could help to define DPP4i efficacy in patients that are refractory to treatment. We aimed to develop a selective, non-invasive, stable-isotope ¹³C-breath test for DPP4. In vitro experiments were performed using high (Caco-2) and low (HeLa) DPP4 expressing cells. DPP gene expression was determined in cell lines by qRT-PCR. A DPP4 selective ¹³C-tripeptide was added to cells in the presence and absence of the DPP4 inhibitor Sitagliptin. Gas samples were collected from the cell headspace and ¹³CO₂ content quantified by isotope ratio mass spectrometry (IRMS). DPP4 was highly expressed in Caco-2 cells compared to HeLa cells and using the ¹³C-tripeptide, we detected a high ¹³CO₂ signal from Caco2 cells. Addition of Sitaglitpin to Caco2 cells significantly inhibited this ¹³CO₂ signal. ¹³C-assay DPP4 activity correlated positively with the enzyme activity detected using a colorimetric substrate. We have developed a selective, non-invasive, ¹³C-assay for DPP4 that could have broad translational applications in diabetes and gastrointestinal disease.

Non-invasive diagnostic tests for Helicobacter pylori infection

BACKGROUND

Helicobacter pylori (H pylori) infection has been implicated in a number of malignancies and non-malignant conditions including peptic ulcers, non-ulcer dyspepsia, recurrent peptic ulcer bleeding, unexplained iron deficiency anaemia, idiopathic thrombocytopaenia purpura, and colorectal adenomas. The confirmatory diagnosis of H pylori is by endoscopic biopsy, followed by histopathological examination using haemotoxylin and eosin (H & E) stain or special stains such as Giemsa stain and Warthin-Starry stain. Special stains are more accurate than H & E stain. There is significant uncertainty about the diagnostic accuracy of non-invasive tests for diagnosis of H pylori.

OBJECTIVES

To compare the diagnostic accuracy of urea breath test, serology, and stool antigen test, used alone or in combination, for diagnosis of H pylori infection in symptomatic and asymptomatic people, so that eradication therapy for H pylori can be started.

SEARCH METHODS

We searched MEDLINE, Embase, the Science Citation Index and the National Institute for Health Research Health Technology Assessment Database on 4 March 2016. We screened references in the included studies to identify additional studies. We also conducted citation searches of relevant studies, most recently on 4 December 2016. We did not restrict studies by language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We included diagnostic accuracy studies that evaluated at least one of the index tests (urea breath test using isotopes such as 13C or 14C, serology and stool antigen test) against the reference standard (histopathological examination using H & E stain, special stains or immunohistochemical stain) in people suspected of having H pylori infection.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the references to identify relevant studies and independently extracted data. We assessed the methodological quality of studies using the QUADAS-2 tool. We performed meta-analysis by using the hierarchical summary receiver operating characteristic (HSROC) model to estimate and compare SROC curves. Where appropriate, we used bivariate or univariate logistic regression models to estimate summary sensitivities and specificities.

MAIN RESULTS

We included 101 studies involving 11,003 participants, of which 5839 participants (53.1%) had H pylori infection. The prevalence of H pylori infection in the studies ranged from 15.2% to 94.7%, with a median prevalence of 53.7% (interquartile range 42.0% to 66.5%). Most of the studies (57%) included participants with dyspepsia and 53 studies excluded participants who recently had proton pump inhibitors or antibiotics.There was at least an unclear risk of bias or unclear applicability concern for each study.Of the 101 studies, 15 compared the accuracy of two index tests and two studies compared the accuracy of three index tests. Thirty-four studies (4242 participants) evaluated serology; 29 studies (2988 participants) evaluated stool antigen test; 34 studies (3139 participants) evaluated urea breath test-13C; 21 studies (1810 participants) evaluated urea breath test-14C; and two studies (127 participants) evaluated urea breath test but did not report the isotope used. The thresholds used to define test positivity and the staining techniques used for histopathological examination (reference standard) varied between studies. Due to sparse data for each threshold reported, it was not possible to identify the best threshold for each test.Using data from 99 studies in an indirect test comparison, there was statistical evidence of a difference in diagnostic accuracy between urea breath test-13C, urea breath test-14C, serology and stool antigen test (P = 0.024). The diagnostic odds ratios for urea breath test-13C, urea breath test-14C, serology, and stool antigen test were 153 (95% confidence interval (CI) 73.7 to 316), 105 (95% CI 74.0 to 150), 47.4 (95% CI 25.5 to 88.1) and 45.1 (95% CI 24.2 to 84.1). The sensitivity (95% CI) estimated at a fixed specificity of 0.90 (median from studies across the four tests), was 0.94 (95% CI 0.89 to 0.97) for urea breath test-13C, 0.92 (95% CI 0.89 to 0.94) for urea breath test-14C, 0.84 (95% CI 0.74 to 0.91) for serology, and 0.83 (95% CI 0.73 to 0.90) for stool antigen test. This implies that on average, given a specificity of 0.90 and prevalence of 53.7% (median specificity and prevalence in the studies), out of 1000 people tested for H pylori infection, there will be 46 false positives (people without H pylori infection who will be diagnosed as having H pylori infection). In this hypothetical cohort, urea breath test-13C, urea breath test-14C, serology, and stool antigen test will give 30 (95% CI 15 to 58), 42 (95% CI 30 to 58), 86 (95% CI 50 to 140), and 89 (95% CI 52 to 146) false negatives respectively (people with H pylori infection for whom the diagnosis of H pylori will be missed).Direct comparisons were based on few head-to-head studies. The ratios of diagnostic odds ratios (DORs) were 0.68 (95% CI 0.12 to 3.70; P = 0.56) for urea breath test-13C versus serology (seven studies), and 0.88 (95% CI 0.14 to 5.56; P = 0.84) for urea breath test-13C versus stool antigen test (seven studies). The 95% CIs of these estimates overlap with those of the ratios of DORs from the indirect comparison. Data were limited or unavailable for meta-analysis of other direct comparisons.

AUTHORS' CONCLUSIONS

In people without a history of gastrectomy and those who have not recently had antibiotics or proton ,pump inhibitors, urea breath tests had high diagnostic accuracy while serology and stool antigen tests were less accurate for diagnosis of Helicobacter pylori infection.This is based on an indirect test comparison (with potential for bias due to confounding), as evidence from direct comparisons was limited or unavailable. The thresholds used for these tests were highly variable and we were unable to identify specific thresholds that might be useful in clinical practice.We need further comparative studies of high methodological quality to obtain more reliable evidence of relative accuracy between the tests. Such studies should be conducted prospectively in a representative spectrum of participants and clearly reported to ensure low risk of bias. Most importantly, studies should prespecify and clearly report thresholds used, and should avoid inappropriate exclusions.

Sex differences in urea breath test results for the diagnosis of Helicobacter pylori infection: a large cross-sectional study

Background

Helicobacter pylori causes peptic ulcer disease and gastric cancer only in a subset of infected persons. Sex differences were shown in results of urea breath test (UBT), a commonly used test for the diagnosis of H. pylori infection. However, factors that might explain these differences, or affect UBT values, are not fully understood. We examined differences in UBT values between H. pylori-infected men and women while adjusting for background characteristics such as age, body mass index (BMI), and smoking.

Methods

A cross-sectional study was undertaken using coded data from the computerized database of Maccabi Health Services in Israel. Included were adults examined for UBT during 2002–2012 and were found H. pylori positive (UBT > 3.5‰). Multivariable linear mixed models were performed to assess the relationship between sex and UBT quantitative results, while adjusting for background characteristics.

Results

A total of 76,403 patients were included (52% of examined patients during the study period). Adjusted mean UBT value was significantly higher in women 33.8‰ (95% CI 33.4, 34.1) than in men 24.9‰ (95% CI 24.5, 25.3). A significant (P < 0.001) interaction was found between sex and smoking, showing diminished sex-differences in UBT results in smokers. Adjusted mean UBT values increased significantly with age and decreased with BMI, and it was higher in people who lived in low vs high socioeconomic status communities and lower in smokers vs non-smokers.

Conclusions

Systemic differences exist between men and women in quantitative UBT results. Host-related and environmental factors might affect UBT quantitative results. These findings have clinical implications regarding confirmation of the success of H. pylori eradication after treatment in various subgroups.

Diagnostic Methods of Helicobacter pylori Infection for Epidemiological Studies: Critical Importance of Indirect Test Validation

Among the methods developed to detect H. pylori infection, determining the gold standard remains debatable, especially for epidemiological studies. Due to the decreasing sensitivity of direct diagnostic tests (histopathology and/or immunohistochemistry [IHC], rapid urease test [RUT], and culture), several indirect tests, including antibody-based tests (serology and urine test), urea breath test (UBT), and stool antigen test (SAT) have been developed to diagnose H. pylori infection. Among the indirect tests, UBT and SAT became the best methods to determine active infection. While antibody-based tests, especially serology, are widely available and relatively sensitive, their specificity is low. Guidelines indicated that no single test can be considered as the gold standard for the diagnosis of H. pylori infection and that one should consider the method's advantages and disadvantages. Based on four epidemiological studies, culture and RUT present a sensitivity of 74.2–90.8% and 83.3–86.9% and a specificity of 97.7–98.8% and 95.1–97.2%, respectively, when using IHC as a gold standard. The sensitivity of serology is quite high, but that of the urine test was lower compared with that of the other methods. Thus, indirect test validation is important although some commercial kits propose universal cut-off values.

[Guidelines for the diagnosis and treatment of Helicobacter pylori infection in Korea, 2013 revised edition]

Since the Korean College of Helicobacter and Upper Gastrointestinal Research has first developed the guideline for the diagnosis and treatment of Helicobacter pylori infection in 1998, the revised guideline was proposed in 2009 by the same group. Although the revised guideline was made by comprehensive review of previous articles and consensus of authoritative expert opinions, the evidence-based developmental process was not applied in the revision of the guideline. This new guideline has been revised especially in terms of changes in the indication and treatment of H. pylori infection in Korea, and developed by the adaptation process as evidence-based method; 6 guidelines were retrieved by systematic review and the Appraisal of Guidelines for Research and Evaluation (AGREE) II process, 21 statements were made with grading system and revised by modified Delphi method. After revision, 11 statements for the indication of test and treatment, 4 statements for the diagnosis and 4 statements for the treatment have been developed, respectively. The revised guideline has been reviewed by external experts before the official endorsement, and will be disseminated for usual clinical practice in Korea. Also, the scheduled update and revision of the guideline will be made periodically.

Randomised clinical trial: a novel rabeprazole extended release 50 mg formulation vs. esomeprazole 40 mg in healing of moderate-to-severe erosive oesophagitis - the results of two double-blind studies

BACKGROUND

Current PPIs may not achieve desired outcomes in some GERD patients due to limited duration of acid inhibition.

AIM

To evaluate a novel rabeprazole extended release (ER), which provides longer duration of drug exposure and acid suppression, in healing and symptomatic resolution of moderate-severe erosive oesophagitis.

METHODS

Patients with LA grade C or D oesophagitis were randomised to rabeprazole-ER 50 mg or esomeprazole 40 mg once daily in two identical 8-week double-blind trials (N = 2130). Two primary endpoints were tested sequentially: (1) healing by 8 weeks [hypothesis: rabeprazole-ER non-inferior to esomeprazole (non-inferiority margin = 8%)], (2) healing by 4 weeks [hypothesis: rabeprazole-ER superior to esomeprazole (P < 0.05)]. The secondary endpoint was sustained heartburn resolution at 4 weeks.

RESULTS

Rabeprazole-ER was non-inferior to esomeprazole in week-8 healing (80.0% vs. 75.0%; 77.5% vs. 78.4%). Week-4 healing (54.8% vs. 50.3%; 50.9% vs. 50.7%) and sustained heartburn resolution (48.3% vs. 48.2%; 53.2% vs. 52.5%) were not significantly different. Post hoc combined results for grade D revealed rabeprazole-ER vs. esomeprazole differences in week-8 healing = 10.4% (95% CI: -1.4%, 22.2%) and week-4 healing = 12.0% (P = 0.048).

CONCLUSIONS

Rabeprazole-ER is as effective as esomeprazole in healing moderate-severe oesophagitis and achieves similar rates of heartburn resolution. Subgroup analysis suggests the possibility of benefit in severe oesophagitis, but this requires further evaluation (ClinicalTrials.gov: NCT00658528 and NCT00658775).

Performance of acidified 14C-urea capsule breath test during pantoprazole and ranitidine treatment

BACKGROUND AND AIM

Urea breath test (UBT) results could be false negative in patients taking antisecretory drugs. This effect would be prevented by citric acid administration during UBT. We prospectively investigated whether acidified 14C-urea capsule prevents false negative UBT results in patients taking antisecretory drugs and show interference with the duration of medications.

METHODS

Sixty Helicobacter pylori positive patients were included. Pantoprazole (40 mg/day) was given to 27 patients for 28 days and ranitidine (300 mg. o.d.) to 33 patients for 60 days. Urea breath tests were repeated on days 14 and 28 in both groups and on day 60 in the ranitidine group.

RESULTS

The baseline mean breath counts of two groups did not show any significant difference. Pantoprazole led to a significant decrease in mean breath counts on day 14 (P < 0.005). Six of 27 and 3 of 25 patients taking pantoprazole developed negative or equivocal UBT results on days 14 and 28, respectively. Two of 32, 2 of 32 and 3 of 21 patients taking ranitidine developed negative or equivocal UBT results on days 14, 28 and 60, respectively.

CONCLUSIONS

The use of acidified 14C-urea capsule did not prevent false negative UBT results in patients taking pantoprazole and ranitidine, and the duration of medication does not affect the test results.

Helicobacter pylori eradication improves gastric histology and decreases serum gastrin, pepsinogen I and pepsinogen II levels in patients with duodenal ulcer

BACKGROUND AND AIM

The aim of this study was to assess the gastric histopathology and serum gastrin-17 and pepsinogens profiles in patients with duodenal ulcer before and after Helicobacter pylori eradication in a population with a very high prevalence of H. pylori. At the same time we assessed the role of H. pylori density on these variables.

METHODS

Eighty Caucasian patients with H. pylori-associated duodenal ulcer before treatment and 1 year after randomized eradication were studied. Among patients with unsuccessful eradication two groups were distinguished according to the data obtained after treatment: the group with negative rapid urease test and decreased bacterial density according to morphological score (partial elimination group); the group with positive rapid urease test and high bacterial density (failed eradication group).

RESULTS

One year after successful eradication, serum levels of gastrin-17, pepsinogen I and pepsinogen II decreased. Similar changes of serum pepsinogen I and pepsinogen II levels were observed in patients with partial elimination of H. pylori infection. In the group with successful eradication, inflammation, activity, atrophy and number of lymphoid follicles in the antral mucosa fell. In the group with partial elimination, antral mucosa activity and H. pylori score reduced. Other morphological changes were statistically non-significant.

CONCLUSION

Patients with duodenal ulcer after successful eradication have improvement of morphological and functional characteristics of gastric mucosa.

Helicobacter pylori e doença péptica: estudo comparativo de métodos diagnósticos

Foram estudados, prospectivamente, 150 pacientes. Estudo endoscópico revelou gastrite crônica em 109 pacientes (72,6%), úlcera gástrica em 6 (4%), duodenite crônica em 9 (6%) e úlcera duodenal em 26 (17,4%). Quanto à avaliação metodológica para pesquisa do Helicobacter pylori, 103 (68,67%) apresentaram teste da urease positivo, 104 (69,33%), positividade histopatológica e 98 (65,33%), positividade sorológica. Não houve diferença estatística entre os métodos. Pela facilidade de realização, o teste da urease credencia-se como o de melhor indicação nos pacientes que também se beneficiarão com o diagnóstico endoscópico. Caso a endoscopia digestiva alta não possa ou não deva ser realizada, está recomendado o teste sorológico.

Inhibition of Helicobacter pylori infection in humans by Lactobacillus reuteri ATCC 55730 and effect on eradication therapy: a pilot study

BACKGROUND

Several studies report an inhibitory effect of probiotics on Helicobacter pylori.

AIM

To test whether Lactobacillus reuteri ATCC 55730 reduces H. pylori intragastric load in vivo, decreases dyspeptic symptoms, and affects eradication rates after conventional treatment.

MATERIALS AND METHODS

In a double-blind placebo-controlled study, 40 H. pylori-positive subjects were given L. reuteri once a day for 4 weeks or placebo. All underwent upper endoscopy, (13)C-urea breath test, and H. pylori stool antigen determination at entry and (13)C-urea breath test and H. pylori stool antigen (used as both qualitative and semiquantitative markers) after 4 weeks of treatment. Sequential treatment was administered subsequently to all.

RESULTS

In vivo, L. reuteri reduces H. pylori load as semiquantitatively assessed by both (13)C-urea breath test delta-value and H. pylori stool antigen quantification after 4 weeks of treatment (p < .05). No change was shown in patients receiving placebo. L. reuteri administration was followed by a significant decrease in the Gastrointestinal Symptom Rating Scale as compared to pretreatment value (p < .05) that was not present in those receiving placebo (p = not significant). No difference in eradication rates was observed.

CONCLUSIONS

L. reuteri effectively suppresses H. pylori infection in humans and decreases the occurrence of dyspeptic symptoms. Nevertheless, it does not seem to affect antibiotic therapy outcome.

Significantly elevated Helicobacter pylori density and different genotype distribution in erosions as compared with normal gastric biopsy specimen detected by quantitative real-time PCR

BACKGROUND AND AIM

Determination of the local densities of Helicobacter pylori and its genotypic variations in gastric biopsy specimens by using novel real-time PCR-based methods could support the precise diagnosis and understanding of H. pylori infections.

METHODS

Serial dilutions of H. pylori (0.016-16 microg/microl), control, bacterial, and human DNA samples were prepared. Fresh-frozen gastric biopsy specimens were taken from 103 patients, and the DNA was isolated. Quantitative determination of the ureaseA gene using hybridization probes with parallel evaluation of an internal human control gene (beta-globin) was performed by real-time PCR. CagA and VacA s1 genotypic characterizations were also performed. The data were compared with urea breath test (UBT), histology, and serological testing.

RESULTS

The presence of H. pylori could be detected by ureaseA-fluorescence energy transfer (53%), UBT (51%), serological testing (48%), and histology (52%) when compared with the gold standard (54%). A significant correlation was found between the quantitative real-time ureaseA/beta-globin ratio-based H. pylori frequency and the UBT results (P<0.01). Significantly increased bacterial density was found in the erosions when compared with the healthy part of the antrum and corpus (P<0.01). Real-time PCR VacA s1 results were in significant correlation (P<0.01) with those of serological tests, but CagA results were not. The genomic profiles (VAC/GAC) were different in 13.7% of the cases, which involved three different locations in the stomach.

CONCLUSION

Real-time PCR was the most reliable method for H. pylori diagnosis. Furthermore, quantification and genotyping could also be performed using this technique. The density of H. pylori was significantly increased in macroscopic erosions.

Helicobacter pylori detection and antimicrobial susceptibility testing

The discovery of Helicobacter pylori in 1982 was the starting point of a revolution concerning the concepts and management of gastroduodenal diseases. It is now well accepted that the most common stomach disease, peptic ulcer disease, is an infectious disease, and all consensus conferences agree that the causative agent, H. pylori, must be treated with antibiotics. Furthermore, the concept emerged that this bacterium could be the trigger of various malignant diseases of the stomach, and it is now a model for chronic bacterial infections causing cancer. Most of the many different techniques involved in diagnosis of H. pylori infection are performed in clinical microbiology laboratories. The aim of this article is to review the current status of these methods and their application, highlighting the important progress which has been made in the past decade. Both invasive and noninvasive techniques will be reviewed.

Quantifying gastric Helicobacter pylori infection: a comparison of quantitative culture, urease breath testing, and histology

Although there are several methods to detect Helicobacter pylori infection, there is no simple validated test to quantify the density of infection, which is believed to play a major role in the pathogenesis of H. pylori-associated gastritis and peptic ulceration. The aim of this study was to evaluate and compare noninvasive and invasive tests for assessing the level of H. pylori infection so as to facilitate the development and clinical testing of new antibiotic treatments. Healthy volunteers (n=323) were screened for H. pylori infection by serology and, if positive (n=86), invited to undergo (13)C urea breath testing (UBT) (n=55). An increase of >2.4 parts per thousand (13)CO(2) at 15 min compared to baseline was considered a positive test. Total cumulative urease activity (mumol) at 60 min was also calculated. UBT-positive subjects underwent endoscopy and nine biopsies were obtained from defined sites for quantitative culture and histological grading using the modified Sydney System. A total of 19 subjects were studied, 4 of whom underwent repeat testing. All subjects were positive for H. pylori by serology, UBT, culture, and histology. The increase in (13)CO(2) at 30 min correlated with the total cumulative urease activity at 60 min (r (2)=0.92, P< 0.0001). Bacterial counts (log cfu/biopsy; mean+/-SD) were 3.9+/-0.5, 3.9+/-0.4, and 3.9+/-0.6 at the lesser curve antrum, greater curve antrum, and corpus, respectively. There was no significant correlation between UBT results and bacterial counts at any biopsy site. Nor was there any significant correlation between the histology grading and either the UBT or the bacterial counts at any site. This study indicates that there is little correlation among the three methods used to measure bacterial burden in H. pylori infection. Thus, decrements in bacterial numbers during single-agent therapy cannot be measured reliably by UBT and therefore cannot be used to evaluate the potential efficacy of novel agents to treat gastric H. pylori infection.

Quantitative Correlation of Helicobacter pylori Stool Antigen (HpSA) Test with the Severity of H. pylori-Related Gastritis

The Helicobacter pylori (H. pylori) load in both stomach and stool and the resulting severity of gastritis are important criteria in validating the status of H. pylori infection. We aimed to assess the reliability of the H. pylori stool antigen (HpSA) test for the primary diagnosis of H. pylori infection by calculating the best cut-off value to obtain the highest sensitivity and specificity in dyspeptic patients. We also investigated the correlation of HpSA test with the severity of gastritis and H. pylori load. The H. pylori statuses of 95 patients were evaluated by the positivity of both rapid urease test and microscopic detection of H. pylori in biopsy specimens, 88 subjects of whom were H. pylori positive. The sensitivity and specificity of the HpSA test were 51.1% (45/88) and 100% (7/7), respectively, according to the manufacturer's recommended cut-off value of 0.16. However, with the best cut-off value of 0.048, calculated by receiver operator characteristics analysis, the sensitivity of the test increased to 92.0% (81/88) with the same specificity. High values of the HpSA test were correlated with high scores of corpus H. pylori load and the severity of antrum and corpus inflammation (p < 0.05). With the best cut-off value of the HpSA test, the primary diagnosis of H. pylori infection can be made with higher sensitivity and specificity. The HpSA test is a helpful tool that evaluates the severity of H. pylori infection and the degree of gastric inflammatory activity and gastric H. pylori load.

Diagnosis of Helicobacter pylori Infection

A large number of studies on diagnostic tests have been published this year. New tests were proposed for the detection of Helicobacter pylori antigens in stools and new molecular methods (real-time polymerase chain reaction) to look for antimicrobial susceptibility. The other standard tests have been applied in different situations to improve the diagnosis of the infection.