Action of gentian violet on Mucosus capsulatus group

Abstract

It has recently been shown by Churchman 1 in two interesting communications bearing on the subject that the aniline dye, gentian violet, has a selective bactericidal action on certain bacteria. The action of the dye has been spoken of as bacteriostatic, indicating that the growth of some species of bacteria is inhibited. In addition to this inhibiting influence, Churchman believes the substance has also a very definite bactericidal action. It was shown in the publications referred to that the action of gentian violet as a bacteriostatic or bactericidal agent presented in a general way a parallelism with the Gram stain. The majority of gram positive bacteria are inhibited by gentian violet, while the majority of gram negative bacteria are not. The action of gentian violet can be observed on the divided plates or by staining with gentian violet and determining subsequently whether the microörganisms so treated will grow on culture media. On divided plates, one half of an ordinary petri dish is covered with plain nutrient agar, the other half with nutrient agar to which has been added an aqueous solution of gentian violet; such a plate when streaked with gram positive bacteria will show a growth only on the side of the plate where there is no gentian violet, while gram negative bacteria usually grow equally well on the plain agar and on gentian violet agar.

Since it seemed possible that the differentiation of closely related species might be accomplished by the use of divided gentian violet plates, the method has been used in a further study of the Mucosus capsulatus group. In all, thirty-six strains of bacteria have been investigated; they include B. ozænæ, B. lactis aerogenes, B. enteriditis, B, pneumoniæ Friedlander, B. rhinoscleromatis, B. capsulatu, and B. Mucosus capsulatus.