Sensitivity tests with griseofulvin were generally speaking in agreement with published data,1 but a variation was introduced in this laboratory by testing the drug simultaneously with penicillinase in order to establish whether it would be inactivated by this enzyme. No influence was found on incorporation of penicillinase into griseofulvin-containing media.2
In order to study the mechanism of the curling factor, colonies of dermatophytes were permitted to develop on solid media (Sabouraud's dextrose agar). Small amount of griseofulvin powder were then deposited on the surface of the agar, a few millimeters distant from one side of the colony. Within a few hours, depending on the distance between the griseofulvin powder and the colony, formerly straight hyphae first became wavy, then curled, clumped together, and looked as degenerated and dejected as can be.
However, after a few days the colony revived and the fungistatic effect of griseofulvin obviously was overcome, since growth occurred not only locally, but also on top of the griseofulvin powder. We have not investigated how this inactivation of the griseofulvin occurs. This method lends itself
SCHWARZ J, LOUTZENHISER JK. Laboratory Experiences with Griseofulvin. AMA Arch Derm. 1960;81(5):694–699. doi:10.1001/archderm.1960.03730050050009
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