Isolation of Cryptococcus neoformans from pigeon manure on two media inducing pigment formation

A newly described medium with esculin for identification of Cryptococcus neoformans was compared with Staib's Guizotia abyssinica extract-creatinine medium (GAEC) with and without diphenyl (DF). Twenty-seven samples of pigeon manure were examined. Cr. neoformans was found in 6 samples (22%) on GAEC plates (-DF); ESC medium (-DF) and malt extract agar allowed isolation from 2 and 3 samples respectively. Cr. neoformans was found in 0 to 2 samples when DF was added. Colonies of Cr. neoformans found on ESC plates had no distinctive pigmentation although inocula of pure cultures produced brown colonies. On GAEC plates some colonies of Cr. neoformans turned brown not until after 2 weeks of incubation. At 1 month the presence of pigmented colonies on GAEC plates (-DF) allowed the identification of 5 of the 6 samples from which Cr. neoformans was isolated. Other yeasts were grown from 26 samples (96%) and Torulopsis candida was found to be more frequent than Cr. neoformans.