Blood Tellurite media is used for: March 2013

Ans. B i.e. Corynebacterium diphtheriae Identification of C. diphtheriae A Gram stain is performed to show gram-positive, highly pleomorphic organisms with no paicular arrangement. Special stains like Albes's stain and Ponder's stain are used to demonstrate the metachromatic granules formed in the polar regions. The granules are called as polar granules, Babes Ernst Granules, Volutin, etc. An enrichment medium, such as Loffler's medium, is used to preferentially grow C. diptheriae. After that, use a differential plate known as tellurite agar, which allows all Corynebacteria (including C. diphtheriae) to reduce tellurite to metallic tellurium. The tellurite reduction is colormetrically indicated by brown colonies for most Cornyebacteria species or by a black halo around the C. diphtheriae colonies.