Frequency of CagA-positive Helicobacter pylori strains in 160 patients subjected to endoscopy

Abstract

Helicobacter pylori is the most significant pathogen associated with gastric diseases, including gastric cancer. Infected patients with strains that are CagA-positive generally have worse outcomes than those infected with CagA-negative strains. Patients infected with CagA-positive strains have a higher risk for developing gastric cancer. To determine the prevalence of CagA-positive H. pylori strains in fecal samples of patients from the Coquimbo Region of Chile, using a non-invasive, nested-qPCR method. We evaluated 160 patients with gastrointestinal symptoms subjected to an upper gastrointestinal endoscopy. DNA was extracted from fecal samples and tested for the presence of H. pylori using nested-qPCR for the ureC gene, and subsequently compared with the results of histology-Giemsa stain from the patients' endoscopic biopsies. When H. pylori was found, the presence of CagA-positive strains was determined via nested-qPCR. The histology-Giemsa stain was positive for H. pylori infection in 123 patients (76.9%), while the analysis of fecal samples detected H. pylori in 129 patients (80.6%). The sensitivity and specificity of nested-qPCR to detect the bacterium was 96.7 and 73.0% respectively. Among patients with the infection, 25% had CagA-positive strains. In this sample of patients, there is a low prevalence of CagA-positive H. pylori strains.