Direct gram stain and urease test to detect Helicobacter pylori

Antral biopsies were obtained by gastrointestinal endoscopy on 143 adult patients with dyspeptic symptoms of gastritis or peptic ulcer disease. A direct Gram stain and a direct urease test were performed on each biopsy in addition to culture. Forty-three biopsies (30%) were considered positive for Helicobacter pylori based on culture or histologic examination, or both. Thirty-one biopsies (72% sensitivity) were positive for both direct tests, whereas 95 of 100 negative cultures were negative for both tests. Thirty-eight of the 43 positive biopsies were Gram stain positive (sensitivity, 88%; specificity, 100%). The direct urease test alone was positive at 4 hr for 29 biopsies (sensitivity, 67%; specificity, 100%) and at 24 hr for 38 biopsies (sensitivity, 74%; specificity, 95%). Rapid presumptive diagnosis of H. pylori in antral biopsies was obtained when at least one direct test, Gram stain or urease, was positive.