Corynebacterium diphtheriae cultivated on Tinsdale agar (TIN). Tinsdale agar is used for the primary isolation and identification of Corynebacterium diphtheriae. It contains L-cysteine and sodium thiosulfate that are H2S indicators. Potassium tellurite is the selective agent (inhibits most of the upper respiratory tract normal flora) that turns the media brown-black as a result from the reduction of potassium tellurite to metallic tellurite.
Cultivation 24 hours, 37 °C in an aerobic atmosphere (growth of C.diphtheriae may be inhibited if Tinsdale Agar is incubated in carbon dioxide-enriched air).