Simple spot test for rapid detection of urease activity

A spot test for the detection of urease activity was developed and evaluated with 761 strains of gram-negative bacteria. The test was compared with the conventional Christensen urea agar slants and urease test on the Vitek Enterobacteriaceae card (Vitek Systems, Inc., St. Ana, Mo.). Of the 348 strains of the Proteus-Providencia-Morganella group that were urease positive, 327 (94%) yielded positive results within 1 min, and all strains yielded positive results within 2 min. All these organisms also gave a positive urease reaction on the Vitek Enterobacteriaceae card test within 5 h and on the Christensen urea agar slants in 4 to 48 h. All the bacteria that did not hydrolyze urea by these two tests also remained negative by the spot test.