Studies on Chancroid. IV. The Ducrey Bacillus: Growth Requirements and Inhibition by Antibiotic Agents.

Abstract

In a comparative study of several strains of Ducrey bacillus with Hemophilus influenzae and H. parainfluenzae, several significant biological differences were noted. The Ducrey bacillus will not grow in a medium which supplies both the X and V factors. Unlike these other spp. of Hemophilus, the Ducrey bacillus will grow in a medium enriched only with blood serum. It will also grow in a medium enriched only with erythrocytes. The agents in serum and in erythrocytes which support growth of the Ducrey bacillus differ in heat stability; that in serum withstands 100[degree] C but not autoclaving, while that in erythrocytes is inactivated by heating to 65[degree] C. Addition of both erythrocytes and serum to the base medium provides a more favorable medium for the growth of the Ducrey bacillus than either one alone. Ducrey colonies will not develop on the surface of a solid medium unless the humidity of the atmosphere is very high. The "satellite phenomenon" is not observed in colonies of Ducrey bacillus. Attempts to separate Ducrey growth factors from whole blood or serum by dialysis have not been successful. The Ducrey bacillus differs significantly from H. influenzae and H. parainfluenzae in susceptibility to inhibition by penicillin and by tyrothricin.