TINSDALE AGAR BASE

Tinsdale Agar is used for the primary isolation and identification of Corynebacterium diptheriae.
The medium differentiates between C. diphtheriae and the diphtheroids found in the upper respiratory tract. This differentiation was based on the ability of C. diphtheriae to produce grayish-black colonies, surrounded by a brown/black halo. Diphtheroids do not have this ability. The dark halo is due to the production of H2S from cystine and sodium thiosulfate, interacting with the tellurite salt.