Etiology of Nongonococcal Urethritis EVIDENCE FOR CHLAMYDIA TRACHOMATIS AND UREAPLASMA

first episode of NGU, and 1 of 39 with no urethritis. Serum IgM immunofluorescent antibody to chlamydia was demonstrated in 16 of 20 men with chlamydia culture positive NGU, and 3 of 39 with chlamydia culture negative NGU, and none of 34 with no urethritis. 9 of 10 culture positive men with cl10 days symptoms developed immunofluorescent antibody seroconversion in paired sera. U. urealyticum was isolated significantly more often and in significantly higher concentration from first voided urine from chlamydia-negative cases of NGU than from chlamydia-positive NGU. Ureaplasmacidal antibody titers increased fourfold in six men, four of whom had negative cultures for ureaplasma. H. vaginalis was isolated from 19 of 33 men with no urethritis and 2 of 69 with NGU. C. trachomatis is susceptible, and U. urealyticum is resistant to sulfonamides. A 10-day course of sulfisoxazole therapy produced improvement in 13 of 13 chlamydia-positive, ureaplasmaThis paper was presented in part at the 15th Interscience Conference on Antimicrobial Agents and Chemotherapy, Washington, D.C., 24-26 September 1975; and at the 33rd Meeting of the American Federation for Clinical Research, Atlantic City, N.J. 1-2 May 1976. Dr. Bowie is the recipient of a fellowship from the Medical Research Council of Canada. Received for publication 9 July 1976 and in revised formn 1 November 1976. negative, and only 14 of 29 chlamydia-negative, ureaplasma-positive NGU cases (P < 0.002). Thus, culture, serology, and response to therapy support the etiologic role of chlamydia in NGU. Quantitative culture and response to therapy suggest U. urealyticum may cause many cases of chlamydia-negative NGU.