Usefulness of picric acid-sauton agar medium for differentiating slowly growing mycobacteria from rapidly growing mycobacteria.

A modified Sauton agar medium containing 0.2% picric acid was useful for differentiating slowly growing mycobacteria from rapidly growing mycobacteria. Slowly growing mycobacteria, with the exception of Mycobacterium simiae, failed to grow on this medium. Rapidly growing mycobacteria, with the exception of Mycobacterium chelonei subsp. chelonei, grew on the medium. These 2 species may therefore be differentiated by the use of the picric acid medium.