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October 1968

Pityrosporum OvaleObservations on Some Aspects of Host-Parasite Interrelationship

Author Affiliations

Charlottesville, Va

From the Department of Dermatology, University of Virginia School of Medicine, Charlottesville.

Arch Dermatol. 1968;98(4):408-422. doi:10.1001/archderm.1968.01610160082018

Using a medium suitable for continuous subculture of Pityrosporum ovale, the following observations have been made about this organism:

  1. The organism grows well in the pH range 7.5-8.3 and gradually acidifies the medium.

  2. Ammonium chloride and several amino acids stimulate growth but exogeneous vitamins seem relatively ineffective in promoting growth. Cysteine, as a sole source of amino nitrogen, does not support growth, possibly because of release of inhibitory sulfur-containing substances.

  3. This organism is incapable of solubilizing wool keratin. It can, however, utilize amino nitrogen-containing substances released from hard keratin by hydrolysis.

  4. Human serum temporarily inhibits the growth of P ovale. The inhibitory capacity is similar to that directed against Cryptococcus neoformans by human serum.

  5. P ovale elaborates substances that substantially inhibit the growth of all dermatophyte organisms so far investigated.