VCN--inhibited strains of Neisseria gonorrhoeae.

W ITH great success we have 11 Ibeen using Thayer-Martin (T-M) medium with vancomycin, colistimethate, and nystatin (VCN) inhibitor (1,2) for the culture of Neisseria gonorrhoeae (3) Specimens from a number of patients with purulent discharges containing large numbers of Gram-negative diplococci, however, have yielded no growth of gonococci on this medium. Our suspicions that some gonococci were suppressed by one of the three antibiotics of T-M medium were confirmed by the work of Reyn (4) who reported that 3 percent of gonococcal strains from 171 cultures were suppressed on a medium containing 3 1?g per milliliter of vancomycin. We thereupon embarked on a study to examine the sensitivity of various wild strains of gonococci to the VCN inhibitor used in the T-M medium and to determine to a limited extent whether vancomycin was the inhibitory substance.