Quantitative culture of Pityrosporon orbiculare.

The author describes for the first time a method to culture Pityrosporon orbiculare quantitatively. Different nonionic detergents were studied for their in vitro effect to minimize aggregation of P. orbiculare. Triton X-100 0.1% had only a slight inhibitory effect when the organism was held less than 2 hours. A critical point in quantitative culturing of P. orbiculare seems to be the medium. With this medium, solitary colonies and optimal growth are achieved. No statistically significant differences were found in quantitative cultures from lesions and normal skin in patients with tinea versicolor, but this was observed when quantitative cultures from lesions and normal skin in patients with tinea versicolor were compared with healthy controls.