Six-hour pigmentation test for the identification of Cryptococcus neoformans.

Cryptococcus neoformans colonies can be identified within 6 h using paper disks containing caffeic acid and ferric citrate. Indentification is based on the development of a dark brown pigment. Saprophytic Cryptococcus species and common clinically isolated yeasts do not develop the brown color. The concentration of the reagents and the method of storage of the impregnated paper disks are critical for the rapid and specific development of the pigment.