Butyrate esterase (4-methylumbelliferyl butyrate) spot test, a simple method for immediate identification of Moraxella (Branhamella) catarrhalis [corrected].

A total of 47 Moraxella (Branhamella) catarrhalis strains, 89 strains of Neisseria spp., and 82 strains of miscellaneous bacteria and yeasts were studied by using a fluorogenic spot method which detects butyrate esterase. A positive butyrate esterase spot test correctly differentiated M. catarrhalis from Neisseria spp., which had a negative butyrate esterase spot test reaction. The test is rapid, simple, and easy to perform. The butyrate esterase spot test was useful for direct identification of M. catarrhalis from primary cultures. However, false-positive reactions may occur with mixed cultures.