The Use of Brilliant Green for the Isolation of Typhoid and Paratyphoid Bacilli from Feces

Abstract

While investigating the effect of various aniline dyes on the growth of bacteria1 we found that brilliant green, aniline green, solid green, smaragd green, and china green, in appropriate dilutions, consistently restrained the growth of the gram-positive bacteria but varied in their action on the gram-negative bacteria. The most important variations were among the members of the colon-typhoid group. The growth of the typhoid bacillus was restrained but slightly, the paratyphoidenteritidis types grew abundantly, whereas many of the colon group grew feebly or not at all. Many aerogenes types, as well as Bacillus proteus and Bacillus pyocyaneus, were unaffected, even when the dye was present in low dilutions. The concentrations at which this differential action was evident varied with the individual dyes. No one dye seemed more selective than another, but brilliant green exhibited the selective action at higher dilutions.