Clinical Trials Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jul 21, 2018; 24(27): 3021-3029
Published online Jul 21, 2018. doi: 10.3748/wjg.v24.i27.3021
New fecal test for non-invasive Helicobacter pylori detection: A diagnostic accuracy study
Andrea Iannone, Floriana Giorgio, Francesco Russo, Giuseppe Riezzo, Bruna Girardi, Maria Pricci, Suetonia C Palmer, Michele Barone, Mariabeatrice Principi, Giovanni FM Strippoli, Alfredo Di Leo, Enzo Ierardi
Andrea Iannone, Michele Barone, Mariabeatrice Principi, Alfredo Di Leo, Enzo Ierardi, Section of Gastroenterology, Department of Emergency and Organ Transplantation, University of Bari, Bari 70124, Italy
Andrea Iannone, Department of Emergency and Organ Transplantation, University of Bari, Bari 70124, Italy
Floriana Giorgio, Bruna Girardi, Maria Pricci, THD SpA, Correggio (Reggio Emilia) 42015, Italy
Francesco Russo, Giuseppe Riezzo, National Institute of Gastroenterology, “S De Bellis” Research Hospital, CastellanaGrotte (Bari) 70013, Italy
Suetonia C Palmer, Department of Medicine, University of Otago Christchurch, Christchurch 8011, New Zealand
Giovanni FM Strippoli, Diaverum Academy, Lund 22229, Sweden
Giovanni FM Strippoli, Diaverum Medical Scientific Office, Lund 22229, Sweden
Giovanni FM Strippoli, Sydney School of Public Health, University of Sydney, Sydney NSW-2000, Australia
Giovanni FM Strippoli, Section of Nephrology, Department of Emergency and Organ Transplantation, University of Bari, Bari 70124, Italy
Author contributions: Iannone A, Di Leo A and Ierardi E designed the research; Iannone A, Giorgio F, Russo F, Riezzo G, Girardi B, Pricci M and Principi M performed the research; Giorgio F, Russo F, Riezzo G, Girardi B and Pricci M collected the data; Iannone A analyzed the data; Iannone A, Palmer SC, Strippoli GF and Ierardi E wrote the paper; Palmer SC, Barone M, Principi M, Strippoli GF, Di Leo A and Ierardi E critically revised the manuscript for important intellectual content.
Institutional review board statement: The study was performed in agreement with the ethical guidelines of the Declaration of Helsinki and the protocol was approved by the local Ethics Committee (Ospedale Consorziale Policlinico, Bari, protocol number 74413).
Informed consent statement: All participants gave written informed consent before inclusion in the study.
Conflict-of-interest statement: Alfredo Di Leo is an advisory board member of THD Spa. Floriana Giorgio, Bruna Girardi and Maria Pricci are employees of THD Spa. All other authors declare no financial support or conflict of interest.
Data sharing statement: The raw data and SAS code used for all analyses are available from the corresponding author.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Enzo Ierardi, MD, Associate Professor, Section of Gastroenterology, Department of Emergency and Organ Transplantation, University of Bari, Piazza Giulio Cesare 11, Bari 70124, Italy.
Telephone: +39-80-5593088 Fax: +39-80-5593088
Received: April 28, 2018
Peer-review started: April 28, 2018
First decision: June 11, 2018
Revised: June 12, 2018
Accepted: June 27, 2018
Article in press: June 27, 2018
Published online: July 21, 2018
Research background

Diagnostic approaches for Helicobacter pylori (H. pylori) infection include invasive and non-invasive testing. The non-invasive 13C-urea breath test and stool monoclonal antigen test have high accuracy for diagnosing the infection, although the stool test has low acceptability in some contexts and needs local validation. The need for upper endoscopy is a limitation to the use of invasive tests. Molecular tests are promising approaches for diagnosing H. pylori infection, due to the added advantage of identifying bacterial DNA mutations associated with antibiotic resistance.

Research motivation

The application of molecular diagnostic tests on gastric biopsy samples is limited by the need for invasive endoscopic procedure. Thus, the non-invasive application of these tests on fecal samples is gaining increasing interest. An accurate non-invasive molecular test may guide first-line eradicating treatments with the potential advantages of increasing bacterial eradication rates and reducing the development of H. pylori resistance to antibiotics. However, existing studies on molecular tests for H. pylori detection in stools show suboptimal quality.

Research objectives

We aimed to assess the accuracy of a new non-invasive molecular test, the THD fecal test, for the diagnosis of H. pylori infection, using 13C-urea breath test as the reference standard. Additionally, we estimated the point prevalence of H. pylori DNA mutations conferring resistance to clarithromycin and levofloxacin.

Research methods

We conducted a prospective two-center diagnostic test accuracy study. We enrolled consecutive people ≥ 18 years old without previous diagnosis of H. pylori infection, referred for dyspepsia between February and October 2017. At enrollment, all participants underwent 13C-urea breath test. Participants aged over 50 years were scheduled to undergo upper endoscopy with histology. Participants collected stool samples 1-3 d after enrollment for the THD fecal test. The detection of bacterial 23S rRNA subunit gene indicated H. pylori infection. We also used the index diagnostic test to examine mutations conferring resistance to clarithromycin and levofloxacin. Independent investigators analyzed the index test and reference standard test results blinded to the other test findings, participants’ information and histology results. We estimated diagnostic accuracy parameters, together with their 95% confidence intervals. The novelty of our research methods included an a priori sample size, a prospective enrollment of consecutive participants, and the blindingof outcome assessors. This approach increased the certainty of our findings.

Research results

Out of 294 participants, 95 (32.3%) had a positive 13C-urea breath test. Four (1.4%) participants withdrew from the study after the enrollment visit. In the 290 participants who completed the study, the THD fecal test sensitivity was 90.2% (CI: 84.2%-96.3%), specificity 98.5% (CI: 96.8%-100%), positive predictive value 96.5% (CI: 92.6%-100%), negative predictive value 95.6% (CI: 92.8%-98.4%), accuracy 95.9% (CI: 93.6%-98.2%), positive likelihood ratio 59.5 (CI: 19.3-183.4), negative likelihood ratio 0.10 (CI: 0.05-0.18). Out of 83 H. pylori infected participants identified with the THD fecal test, 27 (32.5%) had bacterial strains resistant to clarithromycin, 3 (3.6%) to levofloxacin, and 4 (4.8%) to both antibiotics.

Research conclusions

Our results indicate that the THD fecal test has high diagnostic accuracy for the non-invasive diagnosis of H. pylori infection in patients with dyspeptic symptoms, while enabling identification of bacterium resistance to clarithromycin and levofloxacin. The certainty of our findings is based on the rigorous methodological approach used in the assessment of the THD fecal test diagnostic performance. THD fecal testing may inform clinical decision-making and guide individualized therapies to eradicate H. pylori infection.

Research perspectives

The spread of H. pylori resistance to antibiotics has prompted the investigation of the efficacy of antibiotic susceptibility-guided therapies. THD fecal testing may assist in the conduct of randomized trials to evaluate the benefits and harms of tailored eradication strategies in first-line.