Thayer-Martin agar is an enriched, selective medium designed to isolate Neisseria species from clinical specimens. This medium is a modification of chocolate agar, enriched with antibiotics to suppress the growth of contaminating flora. The key components include vancomycin to inhibit Gram-positive bacteria, colistin to suppress Gram-negative organisms other than Neisseria, nystatin to prevent fungal growth, and sometimes trimethoprim to inhibit Proteus species. These selective agents create an environment conducive for the growth of Neisseria while preventing the proliferation of other microorganisms.
