A Medium for the Isolation and Differentiation of <i>Yersinia</i> ruckeri

A new medium, Shotts–Waltman (SW), was developed for the isolation and differentiation of Yersinia ruckeri; Y. ruckeri was distinguished by its ability to hydrolyze Tween 80 and inability to ferment sucrose. SW was shown to be as sensitive as MacConkey and trypticase soy agars for the growth of Y. ruckeri. SW is inexpensive, prepared easily, and should greatly increase the recovery of Y. ruckeri from clinical material and infected fish.