New York City agar is selective due to the addition of which agents?

• A. Colistin, Vancomycin, and Amphotericin B
• B. Ampicillin, Clavulanate, and Nystatin
• C. Gentamicin, Tetracycline, and Amphotericin B
• D. Erythromycin, Rifampin, and Nystatin

Answer: (A)

New York City agar is selective because it includes antimicrobial additives that suppress competing flora while allowing Neisseria species to grow. Colistin inhibits many Gram-negative bacteria other than Neisseria, vancomycin blocks Gram-positive organisms, and an antifungal agent such as amphotericin B prevents fungal contaminants. With these inhibitors in place, Neisseria gonorrhoeae and Neisseria meningitidis can be recovered from clinical specimens because they are relatively resistant to these agents, whereas the rest of the normal flora is suppressed. Some formulations use a similar antifungal (like nystatin) instead of amphotericin B, serving the same purpose of preventing fungal overgrowth.