Effect of biopsies on sensitivity and specificity of ultra-rapid urease test for detection of Helicobacter pylori infection: A prospective evaluation

Advancements in Gastrointestinal System Biomarkers

The requirement for diagnostic surgical operations of gastrointestinal system diseases significantly decreases with the help of proper diagnostic tools. These modalities are also beneficial for identifying postoperative complications, allowing us to diagnose them in earlier stages, and increasing the postoperative survival rates. Biomarkers are considered an integral part of diagnostic examinations. Developments of biomarkers used for diagnosing and treating abdominal diseases are essential for improving our capabilities in non-invasive monitoring. In this chapter, we review both the novel and the routine biomarkers in the diagnosis and follow-up of gastrointestinal system diseases.

Evaluation of Accuracy and Feasibility of a New-Generation Ultra-Rapid Urease Test for Detection of Helicobacter pylori Infection

Helicobacter pylori (Hp) infection can be diagnosed by invasive and noninvasive methods, and, among the former, Rapid Urease Tests (RUTs) are an important option. Accuracy and rapidity of results are fundamental for RUTs. The aim of the study is to prospectively evaluate the sensitivity, specificity and time to positivity of a new-generation ultra-rapid urease test (iNatal duo test) for Hp detection and compare the results with other available RUTs [CLO Test (Campylobacter-Like Organism Test), CP Test (Campylobacter pylori Test) and Pronto Dry]. Gastric biopsies were taken in consecutive patients undergoing upper endoscopy: two in the antrum and two in the body for histology, and one in the antrum and one in the body for each RUT. RUTs were read at 1, 5, 15, 30 and 60 min, 3 h and 24 h after biopsy insertion into the reagent. Histology was considered as “gold standard”. The performance of the tests was evaluated in patients not taking proton pump inhibitors (PPI) (n = 924) by calculation of sensitivity, specificity and positive and negative predictive value. Agreement rate (κ) for every RUT and histology was calculated and compared. The performance of the iNatal duo test was also tested in a subgroup of patients taking PPI (n = 198). Hp was positive in 225/924 patients (24.3%) not taking PPIs and in 56/198 (28.3%) who were taking PPIs. The iNatal duo test was more sensitive than the other RUTs for detecting Hp at every time point. The sensitivity at 5 min was 96.2% in patients not taking PPIs and 92.2% in patients taking PPIs. κ with histology was higher for the iNatal duo test than any other RUT (at 30 min: iNatal duo 0.99, CLO 0.60, CP 0.78, Pronto 0.85, at 15 min: iNatal duo 0.99, CLO 0.46, CP 0.63, Pronto 0.71). In a prospective study, the iNatal duo test demonstrated high accuracy and rapidity for Hp detection, both in patients with and without PPI therapy. This new generation of ultra-rapid urease test could be useful for the rapid and correct management of patients undergoing upper GI endoscopy for suspected Hp infection.

Endoscopic Detection of Helicobacter pylori by the Rapid Urease Test

Helicobacter pylori infection can be detected on endoscopic biopsy of the gastric mucosa, by means of several techniques. The biopsy specimens are usually taken from the prepyloric region, but additional biopsy specimens obtained proximally increase the sensitivity of invasive tests and are recommended, especially if the patient has recently been treated with a proton-pump inhibitor. The effects of an increased risk of sampling error and the lower prevalence of H. pylori infection on the diagnostic accuracy of standard invasive tests needs to be considered. Despite evidence of enhanced yield with additional biopsies, combined Rapid Urease Tests (RUTs) have not been widely adopted. The other endoscopic tests, histology , and culture are also prone to sampling error and adoption of appropriate biopsy protocols should be widely adopted to enhance diagnostic yield.

Blood group antigen-Binding Adhesion2 (BabA2) gene in gastric tissue biopsies as a diagnostic biomarker for Helicobacter pylori infection

BACKGROUND

The Lewis (b) blood group antigen-Binding Adhesion2 (BabA2) has been reported to mediate the attachment of H. pylori to human.

AIM

assessment the diagnostic potential of detection of (BabA2) gene compared with immunostaining of Lewis (b) by specific mouse monoclonal antibodies in gastric biopsies from Egyptian Patients as a diagnostic maker for Helicobacter pylori infection.

MATERIALS AND METHODS

Fifty untreated patients suffering from dyspeptic complaints were enrolled in this study and underwent for upper gastro-duodenal endoscopy. Biopsies were taken for histological examination by (H&E) and immunohistochemical analysis for Lewis b by specific mouse monoclonal antibodies, and scoring of Lewis b expression in gastric tissue biopsy as well as molecular detection of BabA2 gene of H. pylori by PCR. Biochemical analysis was performed to detect the presence of H. pylori urease activity using Rapid Urease Test (RUT).

RESULTS

: Out of 50 gastric biopsies, 41 biopsies were positive for histological, Immunostaining for Lewis b expression and urease activity test (RUT) for H pylori. RUT showed a sensitivity of 87.8%, specificity 88.9%, positive predictive value (PPV) 97.2%, and negative predictive value (NPV) 61.5%. BabA2 gene results revealed that, out of 41 positive biopsied cases, 39 (95.1%) were positive by the PCR test for BabA2 gene. And all 9 negative biopsies (100%) for H pylori negative for BabA2gene so the sensitivity and specificity of BabA2 gene detection in gastric biopsies by PCR were 95.1% and 100%; respectively.

CONCLUSION

: BabA2 gene detection in gastric tissue biopsies could be suggested as a diagnostic biomarker to be included among the other biomarkers routinely performed for clinical diagnosis of H. pylori infection.

Multiplex PCR for detection of Helicobacter pylori infection in gastric biopsies with lower inflammatory score

BACKGROUND

No gold standard has yet been established for the diagnosis of H. pylori infection. A multiplex polymerase chain reaction (mPCR) was developed in this study for rapid, sensitive and specific detection of H. pylori from gastric biopsies.

METHODS

H. pylori infections were determined by in-house rapid urease test (iRUT), culture, histology and multiplex PCR.

RESULTS

A total of 140 (60.9%) from 230 patients were positive for H. pylori infection. H. pylori were detected in 9.6% (22/230), 17% (39/230), 12.6% (29/230) and 60% (138/230) of biopsy specimens by culture, iRUT, histology and mPCR, respectively. mPCR identified H. pylori infection in 100% of biopsies with positive histology and culture. All biopsies with positive iRUT yielded positive PCR except two cases. mPCR also detected H. pylori in additional 116, 101 and 109 biopsies that were negative by culture, iRUT and histology, respectively. Positive samples by mPCR showed lower average in H. pylori density, activity and inflammation scores. The Indians showed the highest prevalence of H. pylori infection compared to the Chinese and the Malays. In addition, Chinese patients with older age were significantly infected compared to other ethnicities.

CONCLUSION

PCR was able to detect the highest numbers of positive cases although the lowest average scores were recorded in the activity, inflammatory and H. pylori density.

A combined antral and corpus rapid urease testing protocol can increase diagnostic accuracy despite a low prevalence of Helicobacter pylori infection in patients undergoing routine gastroscopy

BACKGROUND

The effects of an increased risk of sampling error and the lower prevalence of Helicobacter pylori infection on the diagnostic accuracy of standard invasive tests needs to be considered. Despite evidence of enhanced yield with additional biopsies, combined Rapid Urease Tests (RUTs) have not been widely adopted. We aimed to compare the diagnostic efficacy of a combined antral and corpus rapid urease test (RUT) to a single antral RUT in a low prevalence cohort.

METHODS

Between August 2013 and April 2014 adult patients undergoing a scheduled gastroscopy were prospectively recruited. At endoscopy biopsies were taken and processed for single and combined RUTs, histology and culture using standard techniques. Infection was defined by positive culture or detection of Helicobacter like organisms on either antral or corpus samples.

RESULTS

In all 123 patients were recruited. H. pylori prevalence was low at 36%, n = 44. There was a significant difference in positivity between single and combined RUTs, 20% (n = 25) versus 30% (n = 37), p = 0.0094, (95% CI 0.15-0.04). The number needed to treat (NNT) for an additional diagnosis of infection using a combined versus a single RUT is 4 (95% CI 2.2-11). The only factor associated with a reduction in RUT yield was regular proton pump inhibitor (PPI) use. Overall the sensitivity, specificity, positive and negative predictive value for any RUT test was 84%, 100%, 100% and 92% respectively.

CONCLUSION

Our data suggests taking routine antral and corpus biopsies in conjunction with a combined RUT appears to optimizing H. pylori detection and overcome sampling error in a low prevalence population.

Correlation between positive rate and number of biopsy samples on urease test in childhood Helicobacter pylori infection

To identify the correlation between the number of gastric biopsy samples and the positive rate, we compared the results of urease test using one and three biopsy samples from each 255 children who underwent gastroduodenoscopy at Gyeongsang National University Hospital. The children were divided into three age groups: 0-4, 5-9, and 10-15 yr. The gastric endoscopic biopsies were subjected to the urease test. That is, one and three gastric antral biopsy samples were collected from the same child. The results of urease test were classified into three grades: Grade 0 (no change), 1 (6-24 hr), 2 (1-6 hr), and 3 (<1 hr). The positive rate of urease test was increased by the age with no respect to the number of gastric biopsy samples (one biopsy P = 0.001, three biopsy P < 0.001). The positive rate of the urease test was higher on three biopsy samples as compared with one biopsy sample (P < 0.001). The difference between one and three biopsy samples was higher in the children aged 0-9 yr. Our results indicate that the urease test might be a more accurate diagnostic modality when it is performed on three or more biopsy samples in children.

United Rapid Urease Test Is Superior than Separate Test in Detecting Helicobacter pylori at the Gastric Antrum and Body Specimens

Background/Aims

The rapid urease test (RUT) is an invasive method to diagnose Helicobacter pylori infection, which relies on the acquisition and examination of gastric antrum and body tissues. We determined and compared the efficacy of RUT when the tissues were examined separately or after being combined.

Methods

Two hundred and fourteen patients were included and underwent esophagogastroduodenoscopy from July 2008 to June 2010. The separate test was defined as evaluating the status of infectivity of H. pylori from the antrum and body separately; whereas the united test was carried out putting both tissues from the antrum and body in the same RUT kit. All RUTs were read by a single observer 1, 3, 6, 12, and up to 24 hours later. We also got two biopsy specimens stained with hematoxylin and eosin and quantified H. pylori density was calculated on a scale of 0 to 3.

Results

Overall positivity for H. pylori was 137 (64%) for the separate test and 148 (69.2%) for the united test (p<0.01). The mean time to a positive test was 3.58 hours for the separate test and 1.69 hours for the united test (p<0.01). The correlation between the time to positive RUT and the severity of histology showed r=+0.556 for the antrum (p<0.01) and r=+0.622 for the body (p<0.01).

Conclusions

Combining tissues prior to RUT enhances the detection of H. pylori, as compared with the examination of separate tissues, and shortens the time to develop a positive reaction by approximately 50%. These diagnostic advantages are also accompanied by increased cost-savings.

Can the 1.8 mm transnasal biopsy forceps instead of standard 2.2 mm alter rapid urease test and histological diagnosis?

BACKGROUND AND AIM

Biopsy specimens are taken during transnasal esophagogastroduodenoscopy with 1.8 mm forceps. The aims of this study were to compare the concordance of the Campylobacter-like organism (CLO) test and histological diagnoses between biopsies taken with 1.8 mm and 2.2 mm forceps and to determine whether the concordance of the CLO test could be improved by increasing the number of specimens using 1.8 mm forceps.

METHODS

A total of 200 patients were enrolled. We first performed the CLO test twice using each sample taken with both forceps in 100 patients. The CLO test was conducted three times again after confirming the difference in the CLO test between two forceps: (i) one sample with 1.8 mm forceps; (ii) two with 1.8 mm; and (iii) one with 2.2 mm in the other 100 patients. Additionally, each specimen was taken from the same gastric lesions in 200 patients for the histological diagnosis using both forceps types.

RESULTS

The concordance rate of the CLO test between each sample with 1.8 mm and 2.2 mm forceps was 83% (κ-value, 0.64), and that between two samples with 1.8 mm and one with 2.2 mm was 92% (κ-value, 0.83). The concordance rate of the histological diagnosis with 1.8 and 2.2 mm was 97% (κ-value, 0.84).

CONCLUSIONS

At least two samples using 1.8 mm forceps might be needed to obtain similar results on the CLO test using 2.2 mm. But, the size difference between two forceps did not influence the histological diagnosis.

Real-time PCR for diagnosing Helicobacter pylori infection in patients with upper gastrointestinal bleeding: comparison with other classical diagnostic methods

The aim of this study was to determine the diagnostic usefulness of quantification of the H. pylori genome in detection of infection in patients with upper gastrointestinal bleeding (UGB). A total of 158 consecutive patients with digestive disorders, 80 of whom had clinical presentation of UGB, were studied. The number of microorganisms was quantified using a real-time PCR system which amplifies the urease gene with an internal control for eliminating the false negatives. A biopsy sample from the antrum and corpus of each patient was processed. The rapid urease test, culture, histological study, stool antigen test, and breath test were done. The gold standard was a positive culture or positive results in at least two of the other techniques. When a positive result was defined as any number of microorganisms/human cell, the sensitivity of real-time PCR was greater in bleeding patients, especially in the gastric corpus: 68.4% (95% confidence interval [CI], 52.3 to 84.5%) in non-UGB patients versus 91.5% (95% CI, 79.6 to 97.6%) in UGB patients. When a positive result was defined as a number of microorganisms/human cell above the optimal value that maximizes the Youden index (>3.56 microorganisms/human cell in the antrum and >2.69 in the corpus), the sensitivity and specificity in UGB patients were over 80% in both antrum and corpus. Our findings suggest that some bleeding patients with infection caused by H. pylori may not be correctly diagnosed by classical methods, and such patients could benefit from the improved diagnosis provided by real-time PCR. However, the clinical significance of a small number of microorganisms in patients with negative results in classical tests should be evaluated.

[The Usefulness of the Regular Arrangement of Collecting Venules Pattern for the Determination of Helicobacter pylori Infection]

BACKGROUND/AIMS

In the Helicobacter pylori (H. Pylori)-negative normal stomach, collecting venules are visible over all the gastric body as numerous minute points evaluated with standard endoscopy. This finding was termed regular arrangement of collecting venules (RAC), and its absence suggests H. pylori gastritis. The aim of this study was to evaluate the correlation between the RAC and rapid urease test.

METHODS

Two hundred sixty three consecutive adults undergoing upper digestive endoscopy and rapid urease test were included. The lesser curvature of the lower corpus was evaluated for the RAC pattern using a standard endoscope and different hemoglobin index. Two biopsies from the lesser curvature of the antrum and the greater curvature of the body were collected for rapid urease test.

RESULTS

H. pylori were detected in 51.3% (135/263) patients. Of the 57 patients with H. pylori-negative normal stomachs 53 patients (93%) had RAC. As a determinant of the normal stomach without H. pylori infection, the presence of RAC had 41.4% sensitivity, 97.0% specificity, 93.0% positive predictive value and 63.6% negative predictive value.

CONCLUSIONS

RAC-positive finding by standard endoscopy showed high positive predictive value and specificity of H. pylori-negative normal stomach. RAC-positive finding by standard endoscopy could be an useful finding to predict H. pylori negativity.

Virtual histology

Confocal laser endomicroscopy enables in vivo microscopy of the mucosal layer of the GI-tract with subcellular resolution during ongoing endoscopy. Endomicroscopy opens a new door for immediate tissue and vessel analysis. Different types of diseases can be diagnosed with optical surface and subsurface analysis. Analysis of the in vivo microarchitecture can be used for targeting biopsies to relevant areas. Furthermore, subsurface imaging can unmask microscopic diseases - (microscopic colitis) or bacterial infection (Helicobacter pylori), for example. Molecular imaging is becoming feasible, and this will shortly open the door to new indications in gastrointestinal endoscopy. This chapter reviews the currently rapidly expanding clinical data about endomicroscopy and gives a look into future research.

Confocal laser endomicroscopy for gastrointestinal diseases

Confocal laser endomicroscopy enables in vivo microscopy of the mucosal layer of the gastrointestinal tract with subcellular resolution during ongoing endoscopy. Endomicroscopy opens the door to immediate tissue and vessel analysis. Different types of diseases can be diagnosed with optical surface and subsurface analysis. Analysis of the in vivo microarchitecture can be used for targeting biopsies to relevant areas, and subsurface imaging can unmask microscopic diseases or bacterial infection. Molecular imaging is becoming feasible, which will enable new indications in gastrointestinal endoscopy. This article reviews the current and rapidly expanding clinical data on endomicroscopy and gives a look into future research.

Diagnosis of Helicobacter pylori: improving the sensitivity of CLOtest by increasing the number of gastric antral biopsies

BACKGROUND AND GOAL

The rapid urease CLOtest is commonly used during endoscopy to diagnose the presence of Helicobacter pylori. The aim of this study was to determine whether the sensitivity of the CLOtest can be improved by increasing the number of gastric antral biopsies from 1 to 4.

METHODS

The study included 100 adult patients who were referred for upper gastrointestinal endoscopy and tested positive for H. pylori infection on C urea breath test ("gold standard"). These 100 patients were then randomly divided into 4 equal groups (groups 1 to 4), and underwent an upper gastrointestinal endoscopy. Patients in group 1 had 1 gastric antral biopsy during endoscopy, whereas those in groups 2, 3, and 4 had 2, 3, and 4 biopsies, respectively. The biopsies were placed in the rapid urease CLOtests, which were incubated at room temperature for up to 24 hours, and read for positive results at 1, 6, and 24 hours.

RESULTS

About half of the patients (52%) had a positive CLOtest in group 1, compared to 68% in group 2, 76% in group 3, and 96% in group 4 (group 1 vs. 4 P<0.01). After 1 hour of incubation 96% of the patients in group 4 had a positive CLOtest, compared to 40% in group 3, 12% in group 2, and 4% in group 1.

CONCLUSIONS

Increasing the number of gastric antral biopsies from 1 to 4 significantly improves the sensitivity of the CLOtest, eliminates sampling error, and hastens the time needed by the test to become positive for the diagnosis of H. pylori infection.

Diagnosing Helicobacter pylori in vivo by confocal laser endoscopy

BACKGROUND & AIMS

Confocal laser endomicroscopy enables subsurface microscopic imaging of living tissue during ongoing endoscopy. This case report describes the in vivo detection of Helicobacter pylori by endomicroscopy.

METHODS

Endomicroscopy (Pentax, Tokyo, EC-3870CIFK) was performed by using two different contrast stains: Topical Acriflavine in addition to intravenously applied fluorescein netted the surface and allowed identification of focal accumulation of Helicobacter pylori at the surface and in deeper layer of the gastric epithelium. Biopsies were performed at the antrum and corpus for urease testing and histology. In addition, biopsies were cultured for Helicobacter pylori. Cultured bacteria were re-assessed ex vivo using confocal microscopy with and without acriflavine staining.

RESULTS

Helicobacter pylori infection could be detected in a 70-year-old male by endomicroscopy. Accumulated, as well as single bacteria, could be observed and the distinct shape and flagella of Helicobacter pylori could be identified. Helicobacter pylori infection was proved by histology. Furthermore, ex vivo examination of cultures proved the presence of Helicobacter pylori and the active uptake of acriflavine into the bacteria.

CONCLUSIONS

Endomicroscopy is a new diagnostic approach, which enables the immediate diagnosis of Helicobacter pylori in vivo during standard video endoscopy.