Auxotypes and antibacterial resistance to gonococci with differing susceptibilities to vancomycin.

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Abstract
The responses to vancomycin and 11 other antibacterial drugs and the nutritional requirements of gonococci recovered from 2 selective media were determined. Single urogenital specimens from 508 patients attending a social hygiene clinic in 1975 yielded 97 strains of Neisseria gonorrhoeae; 95 were recovered on VCNT (a modification of Thayer-Martin medium), always inoculated first, and 69 on LC medium containing lincomycin (4 .mu.g/ml) and colistin (5 .mu.g/ml). The 2 drugs at these concentrations in LC medium were not inhibitory for isolates from either medium. Unexpectedly, 3 isolates on VCNT were susceptible to vancomycin at the concentration (3 .mu.g/ml) in VCNT medium; these 3 were typically sensitive to penicillins but were hypersusceptible to erythromycin (inhibited by < 0.05 .mu.g/ml) and rifampin (.ltoreq. 0.02 .mu.g/ml). Resistance to streptomycin (.gtoreq. 500 .mu.g/ml) (22% of the strains) were correlated with increased resistance to penicillins, erythromycin and rifampin in most instances. All streptomycin-resistant gonococci required proline, or arginine, or none of the test compounds. Strains requiring arginine, hypoxanthine and uracil were uniformly sensitive to antibiotics but not hypersusceptible. In contrast, 6 strains of N. gonorrhoeae isolated in Denmark required arginine (not satisfied by ornithine), hypoxanthine and uracil and were hypersusceptible to vancomycin (inhibited by 0.5 .mu.g/ml), erythromycin and rifampin. DNA-mediated transformation showed that all 3 hypersusceptibilities of 1 Danish strain were introduced together into a wild-type gonococcus, suggesting that a mutation of an env (envelope) locus might be responsible for the atypical permeability.