A method of detecting β-D-ribofuranosidase activity in bacterial samples includes the step of incubating a sample to allow bacterial growth in the presence of chromogenic β-D-ribofuranosidase substrate, the cleavage products of which produce an indicator, for instance observable visually. The substrate may be incorporated into solid growth media such as agar. It is of particular utility for detecting bacteria from the genera Yersinia, Shigella, Vibrio, and species Corynebacterium diphtheriae and Arcanobacterium haemolytica. The substrate may be a catechol compound, or an indoxyl compound.