Nagler agar is a selective medium for which type of bacteria?

Nagler agar is a selective culture medium specifically designed to isolate and identify Clostridium perfringens, a bacterium associated with food poisoning and gas gangrene. This medium contains egg yolk, which provides lecithin, allowing the detection of lecithinase activity characteristic of Clostridium species. When Clostridium perfringens grows on Nagler agar, it produces a characteristic opacity around the colonies due to the breakdown of lecithin in the egg yolk by lecithinase, making it easy to identify.

The formulation of Nagler agar and its components are tailored to inhibit the growth of non-target organisms while allowing Clostridium spp. to thrive, showcasing its specificity for this genus. This selective property supports its use in clinical microbiology for diagnosing infections caused by Clostridium.