Phenotypic and Epidemiologic Correlates of Auxotype in Neisseria gonorrhoeae

Previous studies from Seattle, Wash., suggested that strains of Neisseria gonorrhoeae which require arginine, hypoxanthine, and uracil (Arg-Hyx-Ura- auxotype) are uniformly highly susceptible to penicillin G, are relatively resistant to complementdependent killing by heated, pooled human serum, and are associated with disseminated gonococcal infection. For further study of the epidemiology of these strains and for analysis of the susceptibility to penicillin, serum sensitivity, and the nutritional requirements of gonococcal isolates from other cities, a survey was made of urethral and cervical strains isolated in 1972–1974 from 50 randomly selected patients with uncomplicated gonorrhea from each of nine cities. Arg-Hyx-Ura- strains represented >50% of isolates from Seattle and Des Moines, Iowa, 22% of isolates from Denver, Colo., and Dayton, Ohio, and ≤12% of the isolates from Boston, Mass., Newark, N.J., Norfolk, Va., Miami, Fla., and Oakland, Calif. Arg-Hyx-Ura- strains were recovered from 42% of white and 9% of black patients (P < 0.001), and clinics with the highest incidences of these strains had the highest proportion of white patients among those with gonorrhea. Arg-Hyx-Ura- strains were all susceptible to ≤0.125 µg of penicillin Glml and were more resistant than strains with other auxotypes to killing by heat-inactivated human serum plus complement (P < 0.01).