Evaluation of tyrosine medium for the identification of Enterobacteriaceae.

Use of the tyrosine medium in the identification of members of the family Enterobacteriaceae form the basis of this paper. Six hundred and twenty-three strains were tested for their property of tyrosine degradation. Three hundred and seventy-two strains were positive in 24 h and an additional eight strains were positive in 48 to 72 h. These positive strains consisted of all 344 strains of the Proteus-Providencia group, all 25 strains of Citrobacter diversus, and three strains of atypical C. freundii. Our findings suggest that tyrosine degradation is a useful property for separating out the Proteus-Providencia group and in specific identification of C. diversus.