These three culture plates represented a test, used to isolate Neisseria gonorrhoeae bacteria from cultures containing 7 saprophytic, Neisseria spp., which are normal commensal inhabitants of mucosal surfaces, and skin, and rarely cause disease. The middle plate contained a growth medium of glucose-cysteine-blood agar (GCBA), with no added inhibitory chemicals. The culture labeled T-M (PR), was a modified Thayer-Martin (TM) agar, and contained trimethoprim, to inhibit the overgrowth of Proteus (PR) organisms. The culture labeled T-M (VCN), was a modified Thayer-Martin (TM) agar, and contained vancomycin, colistin, and nystatin, in order to kill off most Gram-positive, Gram-negative, and fungal organisms respectively. It is important to note, that the colonial bloom in the middle plate was far greater than either of the other two plates, due to their presence of microorganism inhibitory chemicals.