Use of urease test disks in the identification of mycobacteria.

Use of commercially available urea differentiation disks is a rapid and convenient means of determining the urease activity of mycobacteria. In the study performed, paper disks containing Ewing's Urea R Broth were compared with two other methods of testing for urease production. Over 1,500 tests were performed with recent patient isolates from which at least 15 different species of mycobacteria were identified. The tests were read at intervals for 72 h, and a comparison of test results as to rapidity and accuracy for each species was tabulated. The urea disks showed a faster reaction time when compared with the other two methods. They also showed a high percentage (79 to 100%) of reliability for each species on the first run, based on the expected response.