Buffered charcoal yeast extract agar is the recommended medium for recovery of which organism?

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

Answer: (B)

Legionella pneumophila is extremely fastidious and needs specific nutrients not provided by routine media. Buffered charcoal yeast extract agar delivers what Legionella requires: L-cysteine and iron for growth, plus nutrients from the yeast extract, with charcoal helping to absorb inhibitory substances and stabilize the environment. The buffering maintains a pH that supports Legionella growth, and the overall composition creates a favorable setting for this organism to recover from clinical specimens or environmental samples. The other bacteria listed typically grow well on standard media or on media designed for their own needs (for example, Neisseria on chocolate or selective media, Vibrio on TCBS, Hafnia on routine enteric media), so BCYE is not the usual choice for them.