Partial efficacy of clindamycin against Chlamydia trachomatis in men with nongonococcal urethritis.

Tetracyclines are the drugs of choice for treatment of Chlamydia trachomatis infection, but alternative antimicrobial agents are needed. Clindamycin has moderate in-vitro activity against C. trachomatis. In this study clindamycin (600 mg orally three times daily for seven days) was given to 76 men with nongonococcal urethritis. Initial microbiologic and clinical responses were significantly better in men from whom C. trachomatis was initially isolated, compared with men from whom Ureaplasma urealyticum was initially isolated, but by 42 +/- 7 days after initiation of treatment, persistence or recurrence of urethritis had occurred in 39% of men with either organism initially isolated. C. trachomatis was ultimately reisolated at follow-up evaluation from seven of 23 men who initially had had positive cultures for C. trachomatis. There was no apparent relationship between the in-vitro susceptibility of C. trachomatis and the ultimate response. These results indicate that clindamycin cannot be relied upon to eradicate C. trachomatis from men with urethritis.