Buffered charcoal yeast extract agar is primarily used for recovering which organism?

• A. Hafnia alvei
• B. Legionella pneumophila
• C. Neisseria meningitidis
• D. Vibrio cholerae

Answer: (B)

Legionella species are fastidious and don’t grow well on routine culture media, so they require a specialized medium. Buffered charcoal yeast extract agar provides the nutrients Legionella needs through yeast extract, while the charcoal helps detoxify byproducts and the buffering maintains a stable pH. Crucially, this medium is supplemented with growth factors such as L-cysteine (and often iron), which Legionella specifically requires for replication. That combination creates an environment where Legionella can grow while many other bacteria are inhibited or fail to grow, making this medium the primary choice for recovering Legionella from clinical specimens, especially respiratory samples. The other organisms listed are typically recovered on different, more standard or selective media tailored to their biology, not on BCYE as the primary medium.