Studies on Small Colony Variants of <i>Staphylococcus aureus</i>

Abstract

Small colony variants of bacteria are regarded by some investigators as a filterable stage in a life cycle of the organisms. Other workers do not feel that there is sufficient evidence in support of this theory. Hadley1 has been one of the chief exponents of the idea that bacterial variation represents a cyclical development of the organisms and in this connection he described a small colony filterable form of the Shiga dysentery bacillus and other bacteria.In the present investigation small colony variants of Staphylococcus aureus were studied with respect to their occurrence, morphology, physiological and antigenic properties and filterability. The variants were obtained by plating ageing broth or agar cultures and from cultures in lithium chloride broth. Their occurrence was irregular and rare and no means were found by which this type of variation could be induced. Tiny colonies were not observed at any time in very young cultures except occasionally in broth containing lithium chloride. They appeared...