TBA (24W139)

Two Birds, one set of biopsies: The use of PCR for the diagnosis of Helicobacter pylori anddetection of resistance using biopsies from bedside rapid urease tests.

Author(s)

Stephen D. Molloy Megan Dunne Thomas J. Butler Deirdre McNamara Sinead M. Smith

Department(s)/Institutions

School of Medicine, Trinity College Dublin, Dublin 2 Department of Gastroenterology, Tallaght University Hospital, Dublin 24

Introduction

Introduction: Helicobacter pylori (H. pylori) causes gastritis and increased risk of peptic ulcers and stomach cancer. Patients can be diagnosed with H. pylori by evaluating stomach tissue biopsies using the rapid urease test (RUT), histology and/or culture. Molecular methods offer a rapid alternative for diagnosis and AST than culture and are usually performed using designated fresh biopsy samples.

Aims/Background

Aim: To determine if biopsies from the RUT can be used for a second time in PCR for H. pylori antimicrobial susceptibility testing (AST).

Method

Methods: Ethical approval was granted by the Joint Research Ethics Committee of Tallaght University Hospital and St. James’s Hospital. During routine gastroscopy, subjects had 1 antrum and 1 corpus biopsy taken for routine RUT (Biohit Healthcare). DNA was extracted from the RUT biopsies using the QiaAmp DNA Mini kit (Qiagen) and in-house 16S rRNA PCR was performed for the detection of H. pylori. The PCR-positive samples underwent clarithromycin (CAM) and fluoroquinolone (FQ) AST using the HelicoDR kit (Hain Lifesciences).

Results

Results: In all, RUT samples from 71 patients (mean age: 57 years, 52% female) were analysed. The average concentration of DNA isolated was 139.61±64.89 ng/µL, with an average ratio of absorbances at 260nm and 280 nm of 1.84±0.04. The rate of detection of H. pylori by 16S rRNA PCR was 15% (N=11/71) compared to histology 15% (N=11/71) with results from 94% (N=67) of samples in agreement. The HelicoDR assay confirmed H. pylori infection in all 11 samples deemed positive by 16S rRNA PCR. 6 of 11 samples (54.5%) were CAM resistant and the mutation causing resistance was identified. FQ resistance was not detected in any of the samples.

Conclusions

Conclusions: In this pilot study, RUT biopsies could be re-used for the isolation of high-quality DNA for H. pylori detection and AST with PCR showing great potential as a rapid diagnostic tool while minimising the number of biopsy samples required.