Optimization of a medium for the rapid urease test for detection of Campylobacter pylori in gastric antral biopsies.

We developed a buffered azide-free urea medium which is sensitive, specific, and nontoxic for rapid detection of Campylobacter pylori in gastric biopsies. Detection of urease produced by the organism provides the basis for the test. The substrate is urea in monobasic sodium phosphate buffer, and phenol red provides indication of the pH change that results from urease activity. A rapid change from yellow to red occurs in the presence of C. pylori, even at low concentrations of the organism. A slower color change occurs with higher concentrations of other urease producers, such as Yersinia enterocolitica and Proteus mirabilis. Experience with 51 patients with our medium showed excellent results in detection of C. pylori in gastric mucosal biopsies. In clinical research and practice, a rapid bedside test will be helpful for rapid diagnosis of C. pylori-positive patients.