Schiemann first described Yersinia selective agar as an alternative to MacConkey agar and other media commonly used for isolating Yersinia Enterocolitica, a causative organism of gastroenteritis. Yersinia Enterocolitica, a major food- or waterborne enteric pathogen, has been reported to cause epizootic outbreaks in animals such as diarrhea, lymphadenopathy and pneumonia. Yersinia Selective Agar, a selective and differentiated medium that supports the growth of Y. Enterocolitica and other Yersinia spp.