Improvement in laboratory diagnosis of pulmonary cryptococcosis.

A new differential colour medium prepared with an extract of potatoes and carrots produced ochre-brown pigmentation in Cryptococcus neoformans colonies, identical to that obtained with Guizotia abyssinica seed extract. The pigment formation was observed to be specific for this pathogenic yeast in a survey of 534 yeast-positive specimens during routine diagnostic work; among 47 C. neoformans-positive specimens were 27 sputa and bronchial aspirations, many overgrown by common yeasts.Detection of C. neoformans in the contaminated specimens was credited largely to the differential medium used. Twelve cases of cryptococcosis were investigated between 1962 and 1968, five of which presented involvement of the respiratory tract only.