Methods

Study Population and Laboratory Tests A prospective study was conducted at the Detroit Social Hygiene Clinic from January 4, 1977, through August 9, 1979. Unfrozen sera were tested by the Venereal Disease Research Laboratory (VDRL; Atlanta, Ga.) slide test and by either the fluorescent treponemal antibody-absorbtion (FTA-Abs) test or the microhemagglutination–Treponema pallidum (MHA-TP) test.

Smears from male patients with urethral discharges were gram-stained, and men whose smears contained gram-negative intracellular diplococci were diagnosed as having gonococcal urethritis. When the direct smears gave negative or equivocal results, the urethral exudate was cultured on Thayer-Martin (TM) medium. In addition, specimens from the anal canal and pharynx of each homosexual man were cultured. Every woman had TM cultures of secretions obtained from the endo-cervix and anal canal by use of sterile, plain, cottontipped applicators. Oxidase-positive, gram-negative diplococci of appropriate morphologic configurations were identified as Neisseria gonorrhoeae, and pharyngeal cultures presumptively positive for N. gonorrhoeae were confirmed by sugar ultilization tests. Men who had signs or symptoms of urethritis with cultures negative for gonococci but with urethral discharges containing ten or more polymorphonuclear leukocytes per high-power field were diagnosed as having nongonococcal urethritis (NGU). Trichomonas vaginalis was identified by direct microscopic examination of vaginal secretions.