Laboratory tests for the evaluation of Helicobacter pylori infections

The Diagnostic Tests for Detection of Helicobacter pylori Infection

Helicobacter pylori causes one of the most common infections in human populations. The role of this bacterium in chronic gastritis, gastric ulcer, gastric cancer, as well as extra-digestive diseases such as ischemic heart disease and chronic obstructive pulmonary diseases, is well known. Prevention and control of these diseases can occur by early diagnosis and eradication of H. pylori infection. At present, different methods have been established to detect H. pylori infection. The biopsy-based tests, which are known as invasive methods, such as rapid urease test and histology, have the highest specificity among the others. Similarly, culture of biopsy samples is used for diagnosis of H. pylori infection. It has a high specificity value, and also allows us to perform antibiotic sensitivity testing. On the contrary, polymerase chain reaction and other molecular methods have good sensitivity and specificity, and can be used for detection of H. pylori infection, its virulence factors, and eradication success after treatment. While serological tests are more appropriate for epidemiological studies, their main weakness for clinical use is low specificity. Overall, specificity and sensitivity, cost, usefulness, and limitation of tests should be considered for selection of detection methods of H. pylori in each country.

Molecular detection and corelation of Helicobacter pylori in dental plaque and gastric biopsies of dyspeptic patients

Helicobacter pylori is a microaerophilic organism, which colonizes in the gastric mucosa. Its role in etiology and development of acute and chronic gastritis and peptic ulcer diseases is scientifically proved. Oral cavity especially supragingival, subgingival plaque and so forth simulate the same microaerophilic environment favorable for the growth of this bacterium.

AIM

Detection of H. pylori simultaneously in the oral cavity and gastric mucosa of patients suffering from gastric pathologies.

OBJECTIVES

To detect H. pylori in the oral cavity and gastric mucosa using endoscopy, urease test and real-time polymerase chain reaction (PCR) (urease A gene). Determining its association and corelation with patient demographics, oral hygiene maintenance and periodontal disease status.

MATERIALS AND METHODS

Endoscopic examination, oral findings oral hygiene index-simplified (OHI-S) and community periodontal index and treatment needs (CPITN) indices were recorded. Antral biopsies and supragingival plaque samples were taken from 56 dyspeptic adult patients. The collected samples were subjected to histological examination, urease broth test and urease A gene amplification using real-time PCR.

RESULT

H. pylori was detected in the supragingival plaque of individuals with H. pylori-induced gastric diseases using rapid urease test and real-time PCR analysis. Occurrence of same strain of H. pylori simultaneously in plaque and gastric mucosa was observed. Positive correlation was obtained between the collected indices and quantity of H. pylori colonization.

Helicobacter pylori-derived Heat shock protein 60 enhances angiogenesis via a CXCR2-mediated signaling pathway

Helicobacter pylori is a potent carcinogen associated with gastric cancer malignancy. Recently, H. pylori Heat shock protein 60 (HpHSP60) has been reported to promote cancer development by inducing chronic inflammation and promoting tumor cell migration. This study demonstrates a role for HpHSP60 in angiogenesis, a necessary precursor to tumor growth. We showed that HpHSP60 enhanced cell migration and tube formation, but not cell proliferation, in human umbilical vein endothelial cells (HUVECs). HpHSP60 also indirectly promoted HUVEC proliferation when HUVECs were co-cultured with supernatants collected from HpHSP60-treated AGS or THP-1 cells. The angiogenic array showed that HpHSP60 dramatically induced THP-1 cells and HUVECs to produce the chemotactic factors IL-8 and GRO. Inhibition of CXCR2, the receptor for IL-8 and GRO, or downstream PLCbeta2/Ca2+-mediated signaling, significantly abolished HpHSP60-induced tube formation. In contrast, suppression of MAP K or PI3 K signaling did not affect HpHSP60-mediated tubulogenesis. These data suggest that HpHSP60 enhances angiogenesis via CXCR2/PLCbeta2/Ca2+ signal transduction in endothelial cells.

Utility of diagnostic tests for detection of Helicobacter pylori in children in northeastern Mexico

BACKGROUND

The presence of Helicobacter pylori in pediatric population has been associated with recurrent abdominal pain (RAP), although this association is unclear. One of the major problems in studying the role of H. pylori in RAP is that methods used to detect the bacteria in children have poor sensitivity and specificity. The aims of the present study were to determine the prevalence of H. pylori in pediatric patients with RAP in northeastern Mexico and to assess the diagnostic utility of invasive tests and serology in this population.

METHODS

A total of 40 patients (mean age, 7.9 years; range 2-16 years; F: M, 0.81), who underwent an endoscopy procedure for RAP, were studied. The presence of H. pylori was assessed using invasive diagnostic tests (culture, rapid urease test, polymerase chain reaction and histology) and one non-invasive test: determination of IgG antibodies. The prevalence of H. pylori in the present group and the diagnostic utility for each test were evaluated.

RESULTS

The prevalence of H. pylori in the present pediatric group with RAP was 12.5-42.5% depending on the criteria of positivity used. The non-invasive methods (serology) had acceptable values in sensitivity and specificity in comparison with invasive tests.

CONCLUSIONS

This is the first report on prevalence of H. pylori in pediatric patients with RAP from the northeastern region of Mexico. The prevalence of H. pylori was low compared with the adult population in the same geographic region. Serology had the best diagnostic utility.

Hyperemesis gravidarum and Helicobacter pylori infection: a systematic review

OBJECTIVE

To systematically review studies examining the relationship between hyperemesis gravidarum and Helicobacter pylori (H pylori) infection.

DATA SOURCES

A 1966 to January 2007 search using MEDLINE/PubMed, EMBASE, and Web of Science included MeSH terms: "Helicobacter pylori," "Helicobacter infections," "hyperemesis gravidarum," and the text words "nausea," "vomit," "pregnancy," and "Helicobacter." References of selected papers were examined for additional relevant studies.

METHODS OF STUDY SELECTION

We evaluated studies investigating a relationship between hyperemesis gravidarum and H pylori infection. Studies were included in which the diagnosis of hyperemesis gravidarum was made at or before entry into the study, and H pylori diagnosis was made by serum antibody sample, gastric biopsy, saliva test, or stool sample. The search produced 169 titles; 22 were reviewed in further detail.

TABULATION, INTEGRATION, AND RESULTS

Fourteen case-control studies met established criteria, involving 1,732 participants and controls tested for H pylori infection. Studies were evaluated according to patient demographics and study methodology (case definition, exclusion criteria, H pylori testing). An estimate of the odds ratios with 95% confidence intervals was calculated by using a random effects model for dichotomous variables with review article software. Ten studies showed a significant association between hyperemesis gravidarum and H pylori infection. Odds ratios varied from 0.55 to 109.33; three results were less than 1.0. Tests for heterogeneity applied to several subgroups were considerable with values above 75% for all groups.

CONCLUSION

An association between hyperemesis gravidarum and H pylori infection is suggested by this systematic review. However, the considerable heterogeneity among studies highlights study limitations.

Stool antigen tests in the diagnosis of Helicobacter pylori infection before and after eradication therapy

AIM

To evaluate two enzyme immunoassay-based stool antigen tests, Premier Platinum HpSA and Amplified IDEIA HpStAR, and one rapid test, ImmunoCard STAT! HpSA, in the primary diagnosis of Helicobacter pylori (H pylori) infection and after eradication therapy.

METHODS

Altogether 1 574 adult subjects were screened with a whole-blood H pylori antibody test and positive results were confirmed with locally validated serology and (13)C-urea breath test. All 185 subjects, confirmed to be H pylori positive, and 97 H pylori-negative individuals, randomly selected from the screened study population and with negative results in serology and UBT, were enrolled. After eradication therapy the results of 182 subjects were assessed.

RESULTS

At baseline, the sensitivity of HpSA and HpStAR was 91.9% and 96.2%, respectively, and specificity was 95.9% for both tests. ImmunoCard had sensitivity of 93.0% but specificity of only 88.7%. After eradication therapy, HpSA and HpStAR had sensitivity of 81.3% and 100%, and specificity of 97.0% and 97.6%, respectively. ImmunoCard had sensitivity of 93.8% and specificity of 97.0%. HpSA, HpStAR, and ImmunoCard had PPV 77%, 80%, and 75%, and NPV 98%, 100%, and 99%, respectively.

CONCLUSION

In primary diagnosis, the EIA-based tests performed well. After eradication therapy, negative results were highly accurate for all the three tests. HpStAR had the best overall performance.

Occurrence of Helicobacter pylori in dental plaque and saliva of dyspeptic patients

BACKGROUND

Helicobacter pylori infection in the stomach is associated with gastric and duodenal ulcers, gastric cancers and gastric lymphoma. The organism is transmitted by ingestion, but the oral-oral route and the fecal-oral route are also suggested. The prevalence of infection with H. pylori in developing countries, including Brazil, is higher than in developed countries.

PURPOSE

This study aimed to evaluate the role of the oral cavity as a reservoir of this species, by evaluating the occurrence of H. pylori in supragingival dental plaque and in saliva of Brazilian dyspeptic patients, whether harboring the organism or not in the stomach.

MATERIAL AND METHODS

Forty-nine patients reporting dyspeptic symptoms were subjected to oral clinical examination and collection of saliva and supragingival dental plaque samples prior to the endoscopic examination. The detection of H. pylori in oral samples was performed by PCR using 16S rRNA primers. The bacteria were detected in stomach by means of the rapid urease test.

RESULTS

Helicobacter pylori was detected in the stomach of 20 of 49 subjects reporting dyspeptic symptoms. The organism was detected in only one supragingival plaque sample, obtained from a patient positive for the urease test in the stomach and in none of the salivary samples.

CONCLUSION

Supragingival dental plaque and saliva may not be relevant reservoirs of H. pylori.

Diagnosis of helicobacter pylori infection by polymerase chain reaction: is it worth it?

The aim of this study was to determine to what degree polymerase chain reaction (PCR) was superior to histology and culture, and whether a noncommercial urease test was of value, in detecting Helicobacter pylori in gastric biopsy specimens. Gastric biopsy specimens from the antrum and corpus of 134 consenting patients were subjected to PCR, targeting the glmM (ureC) gene, histology, culture, and a rapid urease test. PCR detected H. pylori in the biopsy specimens from 59 patients. All methods showed a high degree of sensitivity and specificity, but histology gave 2 false-negatives, and culture and the urease test gave 1 false-negative compared with PCR. PCR of a glmM gene segment was superior to the other methods for the detection of H. pylori infection and was comparable to histology in terms of cost. Nevertheless, in this study, histology and culture were found to be relatively reliable methods for examining gastric biopsy specimens.

Selective pressure on the allantoicase gene during vertebrate evolution

During vertebrate evolution, the uric acid degradation pathway has been modified and several enzymes have been lost. Consequently, the end product of purine catabolism varies from species to species. In the past few years, we have focused our attention on vertebrate allantoicase (an uricolytic pathway enzyme), whose activity is present in certain fish and amphibians only, but whose mRNA we detected also in mammals. As allantoicase activity disappeared in amniotes, we wonder why these sequences not only remain present in the mammalian genome, but are still transcribed. To elucidate this issue, we have cloned and analyzed comparable cDNA sequences of different organisms from ascidians to mammals. The analysis of the nonsynonymous-synonymous substitution rate that we performed on the coding region comprising exons 3 to 8 by means of maximum likelihood suggested that a certain amount of purifying selection is acting on the allantoicase sequences. Some implications of the preservation of an apparently unnecessary gene in higher vertebrates are discussed.

Non-invasive diagnosis of Helicobacter pylori infection: simplified 13C-urea breath test, stool antigen testing, or DNA PCR in human feces in a clinical laboratory setting?

OBJECTIVES

(1) To compare two stool antigen EIAs (HpSA, FemtoLab) and PCR of ureaseA and cagA in feces, with (13)C-urea breath test (UBT). (2) To ascertain whether a simplified UBT (breath collection time = 10 min) is as reliable as the standard assay (30 min).

DESIGN AND METHODS

Helicobacter pylori status was recorded in Group 1 (n = 187) by UBT, H. pylori stool antigen, ureA and cagA PCR in feces. UBT with 10, 20 and 30 min sampling was performed in Group 2 patients (n = 283).

RESULTS

The sensitivity and specificity of HpSA, FemtoLab, and ureA were 67% and 99%, 90% and 96%, 35% and 98%, respectively. cagA results were positive in 16/48 H. pylori-positive, and in 5/100 H. pylori-negative patients. The results of UBT with a 10- and 30-min sampling strictly overlapped.

CONCLUSION

UBT with 10 min breath collection and FemtoLab stool antigen assay are the most reliable non-invasive tests to diagnose H. pylori infection.

Gastrointestinal tract cytology: advancing horizons

Tide and ebb of interest in gastrointestinal tract cytology has followed technical advances in this field over the last 60 years. Cytologic samples can be obtained using gastric lavage, abrasive balloons, mucosal brushing, and fine needle aspiration (under percutaneous image guidance, endoscope and endoscopic ultrasound guidance). These advances now allow simultaneous performance of brushing the abnormal mucosa, obtaining fine needle aspirates and excising mucosal biopsy samples for evaluation. Use of endoscopic ultrasound guided fine needle aspirates now help to obtain diagnosis of submucosal lesions, preoperative staging of gastrointestinal tract malignancies and help determine further management of patients. Such advances have brought pathologists to the forefront of the patient management team for the treatment of gastrointestinal tract lesions. This manuscript reviews the advantages and limitations of each cytology associated technique as well as reviews the salient diagnostic features, differential diagnosis and diagnostic pitfalls of gastrointestinal tract lesions. Finally, it suggests the modalities best suited to obtain diagnosis for various gastrointestinal tract lesions.

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.