Tween 80 opacity test responses of various Candida species

A total of 111 Candida isolates representing 11 species were examined for their respective responses to a Tween 80 opacity test. The strains of Candida albicans and C. tropicalis that were examined produced an opacity response around their colonies at 2 to 3 days postinoculation. A second group of Candida species yielded a halo around their colonies at 8 to 10 days postinoculation. The remaining Candida species did not produce a positive test response through 10 days postinoculation. The strains of C. dubliniensis were easily differentiated from strains of C. albicans by this test. The Tween 80 opacity test is simple and economical to prepare and is easy to interpret.