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

Abstract

SUMMARY The responses to vancomycin and 11 other antibacterial drugs and the nutritional requirements of gonococci recovered from two 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 l.g/ml) and colistin (5 Mg/ml).The two drugs at these concentrations in LC medium were not inhibitory for isolates from either medium. Unexpectedly, three isolates on VCNT were susceptible to vancomycin at the concentration (3 ,ug/ml) in VCNT medium; these three were typically sensitive to penicillins but were hypersusceptible to erythromycin (inhibited by (0 05 ,Ag/ml) and rifampin ((0-02 yg/ml). Resistance to streptomycin (>500 jig/ml) (22% of the strains) was 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, six strains of N gonorrhoeae isolated in Denmark required arginine (not satisfied by ornithine), hypoxanthine, and uracil and were hypersusceptible to vancomycin (inhibited by 0S5 M4g/ml), erythromycin, and rifampin. DNA-mediated transformation showed that all three hypersusceptibilities of one 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.

Differences in nitric oxide steady states between arginine, hypoxanthine, uracil auxotrophs (AHU) and non-AHU strains ofNeisseria gonorrhoeaeduring anaerobic respiration in the presence of nitrite

“…AHU strains were uniformly hypersusceptible to vancomycin (Exner et al 1982; Pace and Catlin 1986), suggesting that a mutation of an envelope locus may be responsible. This could mean a number of things are occurring within these strains.…”

Vancomycin hypersusceptibility in Neisseria gonorrhoeae isolated from patients involves diverse mutations

“…Strains isolated from patients more recently, however, display widely differing levels of susceptibility (1,7). Partial resistance to benzylpenicillin results from the cumulative effects of the chromosomal loci penA, mtr (multiple transformable resistance), and penB (14,26).…”