Natural Occurrence of Rough Variant of a Yeast, Candida albicans

Abstract

IN the course of an investigation by Dr. M. J. Marples, of this Department, and myself upon the effects of antibiotics upon the yeast flora of the mouth, R colonies of Candida albicans have been found upon repeated occasions on primary cultures which had been incubated at 37° C. for two days. The occurrence of dissociated, rough variants of Candida albicans, which show a reduced pathogenicity to rabbits, has been noted in the literature since 1935. To our knowledge all these variants have been reported as occurring in old laboratory cultures maintained upon artificial media for periods of years, or else have been induced more rapidly by special conditions such as treatment with immune serum and lithium chloride. Our cultures were made by plating saline mouth-washings upon Sabouraud agar of pH 4. Continuous variation was observed, from colonies differing only by a central depression from normal smooth colonies upon the same plate, to smooth colonies haloed by a ring of mycelium in the medium, and to colonies so raised, rough and warty that they appeared to be, on casual inspection, of a wholly different species. These isolates upon appropriate media showed the typical chlamydospore formation and biochemical characters of C. albicans.