Etiologies of postgonococcal urethritis in homosexual and heterosexual men: roles of Chlamydia trachomatis and Ureaplasma urealyticum.

Before treatment for urethral gonorrhea, Chlamydia trachomatis was isolated from 18% and Ureaplasma urealyticum from 37% of 121 men. C. trachomatis was recovered from none of 18 homosexual men who had gonorrhea and from 22 of 95 heterosexual men who had gonorrhea (P less than 0.05). After treatment with a penicillin, postgonococcal urethritis occurred significantly more often in heterosexual than in homosexual men (P less than 0.002). Postgonococcal urethritis developed in all men from whom C. trachomatis was isolated. Among men without U. urealyticum infection, postgonococcal urethritis was significantly associated with C. trachomatis infection (P less than 0.02). Among men without C. trachomatis infection, postgonococcal urethritis was less closely associated with U. urealyticum infection (0.1 greater than P greater than 0.05). Postgonococcal urethritis was least frequent among men who had neither C. trachomatis nor U. urealyticum infection.