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

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

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

Answer: (B)

The key idea is that buffered charcoal yeast extract agar is a specialized medium designed to grow Legionella species, which are fastidious and have particular nutrient needs. This medium provides cysteine and iron, essential growth factors for Legionella, and the charcoal in the agar helps neutralize toxic substances that can inhibit these fragile bacteria. The buffering keeps the pH stable, which supports their growth as well. In practice, BCYE is used (often with added selective antibiotics) to isolate Legionella from respiratory specimens and environmental samples because other bacteria won’t grow as well, if at all, on this medium. The other organisms listed—Hafnia alvei, Neisseria meningitidis, and Vibrio cholerae—do not require BCYE for growth and are typically recovered on more routine or differently selective media. So the medium is best suited for recovering Legionella pneumophila.

The key idea is that buffered charcoal yeast extract agar is a specialized medium designed to grow Legionella species, which are fastidious and have particular nutrient needs. This medium provides cysteine and iron, essential growth factors for Legionella, and the charcoal in the agar helps neutralize toxic substances that can inhibit these fragile bacteria. The buffering keeps the pH stable, which supports their growth as well. In practice, BCYE is used (often with added selective antibiotics) to isolate Legionella from respiratory specimens and environmental samples because other bacteria won’t grow as well, if at all, on this medium. The other organisms listed—Hafnia alvei, Neisseria meningitidis, and Vibrio cholerae—do not require BCYE for growth and are typically recovered on more routine or differently selective media. So the medium is best suited for recovering Legionella pneumophila.