Coccus Forms of Corynebacterium Diphtheriae

Abstract

Coccus forms in cultures of the diphtheria bacillus have presented an interesting problem for many years. Although they were at first believed to be contaminants, careful technic proved that they could be found in pure cultures of the diphtheria organism. Later it was believed that these coccus forms represented involution or degenerate forms found in aging cultures or occurring when the organisms were subjected to unfavorable conditions. The present tendency to regard atypical forms of many bacterial species as definite stages in a developmental cycle has led several workers to believe that the coccus forms of the diphtheria bacillus represent a stage in the life cycle of the organism. Therefore, the problem remains to determine whether these coccus forms represent transitory morphologic variations, resulting from unfavorable cultural conditions, or a stage in the life cycle of the organism. There is also the third possibility that these forms may be produced by both of the aforementioned processes, according to the condition of the culture.