Micro-aerophilic and anaerobic growth of Pityrosporum species.

Pityrosporum orbiculare, P. ovale, and P. pachydermatis showed the same luxuriant growth when cultured under aerobic conditions, in an aerobic milieu with 7% CO2, and under micro-aerophilic conditions. The species survived and even multiplied under strictly anaerobic conditions. These findings may explain how P. orbiculare and P. ovale can survive in the deeper parts of hair follicles. On a medium that enhanced the production of filaments in Pityrosporum, filaments were more pronounced in the micro-aerophilic environment. Macroscopically, P. ovale showed a more luxuriant growth than P. orbiculare on this medium, but microscopically the same type of filaments were produced.