Which culture medium is used for isolating Corynebacterium diphtheriae?

Corynebacterium diphtheriae is best isolated using Loeffler's agar, which is a selective medium specifically designed for this purpose. Loeffler's agar enhances the growth of C. diphtheriae by providing the necessary nutrients while also allowing for the observation of characteristic morphologies that can indicate the presence of this bacterium. Additionally, it supports the production of metachromatic granules, which are a key feature in identifying C. diphtheriae under the microscope.

Other media such as nutrient agar, MacConkey agar, and blood agar are not as specialized for C. diphtheriae. Nutrient agar is a general-purpose medium that supports a wide variety of non-specific bacterial growth and does not provide the selective environment needed for isolating this organism. MacConkey agar, while useful for isolating gram-negative bacteria, inhibits the growth of gram-positive organisms like C. diphtheriae. Blood agar is more versatile, allowing for the growth of many bacteria and detection of hemolytic activity, but it lacks the specificity and the enriched conditions found in Loeffler's agar tailored for C. diphtheriae.