What is the appropriate media for culturing suspected Corynebacterium diphtheriae from a nasopharyngeal swab?

Corynebacterium diphtheriae is the bacterium responsible for diphtheria and requires specific culture media that promote its growth while suppressing the growth of other organisms. Tinsdale medium is a specialized type of agar that is particularly suited for isolating C. diphtheriae. It contains tellurite, which inhibits the growth of contaminating flora and allows C. diphtheriae to reduce the tellurite, resulting in characteristic black colonies.

The composition of Tinsdale medium, which also includes other nutrients, is designed to provide an optimal environment for the growth of C. diphtheriae while helping to distinguish it from other similar species based on its metabolic properties. This selectivity is crucial in a clinical setting where accurate identification is necessary for treatment decisions.

In contrast, the other media options listed do not provide the same level of specificity for C. diphtheriae. Chocolate agar supports the growth of a variety of bacteria including those that require enriched nutrients, but it does not specifically select for C. diphtheriae. Thayer-Martin agar is primarily used for isolating Neisseria gonorrhoeae and may not effectively suppress other bacteria that could outcompete C. diphther