Characteristics of pathogenic Neisseria spp. isolated from homosexual men

Oropharyngeal, urethral, and rectal cultures for pathogenic Neisseria spp. were collected from 815 homosexual men attending a community clinic in Chicago. Meningococci were characterized by serogrouping and antimicrobial susceptibility testing. Gonococci were auxotyped, and susceptibilities to penicillin and tetracycline were determined. Of the 815 men tested, 42.5% carried meningococci in the oropharynx. Gonococci were recovered from the urethra, rectum, and oropharynx of 18.5, 16.3, and 5.6%, respectively. Meningococci were also recovered from the urethra (6 patients) and the rectum (15 patients). Some of these isolates were identical to the isolates from the oropharynges of the same patients, whereas others were distinct from the oropharyngeal isolates by serogroup or antimicrobial susceptibilities. Serogroups B, W135, and C comprised over 90% of the meningococci. Almost 80% of the gonococcal strains required minimal inhibitory concentrations greater than 0.06 micrograms of penicillin per ml, whereas greater than 90% of the meningococci were inhibited at this concentration. Auxotyping demonstrated three major auxotypes: Zero (required none of the nutrients tested), 60%; arginine requiring, 19.4%; and proline requiring, 12.3%. Only four strains (1.2%) required arginine, hypoxanthine, and uracil.