Which agar is used for identifying Corynebacterium diphtheriae?

Tinsdale agar is specifically designed for the isolation and identification of Corynebacterium diphtheriae, the bacterium responsible for diphtheria. This medium contains ingredients that allow for the selective growth of C. diphtheriae while inhibiting other bacteria. Tinsdale agar has a characteristic appearance that helps in the identification of C. diphtheriae; colonies typically produce a black color due to the reduction of tellurite in the agar. The unique properties of Tinsdale agar make it the most suitable medium for detecting this pathogen, distinguishing it from other types of agar which are not specifically tailored for this purpose.

Blood agar is more general and can grow a wide range of organisms, while chocolate agar is enriched but does not specifically enhance the growth of C. diphtheriae. MacConkey agar is selective for gram-negative organisms and would not support the growth of C. diphtheriae effectively, as it is a gram-positive bacterium. Thus, Tinsdale agar stands out as the optimal choice for identifying C. diphtheriae.