In vitro and in vivo efficacy of antimicrobials against Chlamydia trachomatis.

With the exception of lymphogranuloma venereum, the treatment of Chlamydia trachomatis infections in the genital tract or acquired from the genital tract is relatively easy. In general, in vivo activity of antimicrobials against C. trachomatis correlates well with in vitro activity if sufficient antimicrobial is given for a long enough duration. Tetracycline and erythromycin and their derivatives remain the treatments of choice because of combined activity against C. trachomatis, in addition to most isolates of Neisseria gonorrhoeae and Ureaplasma urealyticum. Rifampin, sulfonamides, or trimethoprim-sulfamethoxazole can only be used if C. trachomatis alone is being treated. Although multiple dose penicillins may be significant activity in vivo, their use is not encouraged. Other antimicrobials like aminocyclitols, cephalosporins, and metronidazole have no activity. Seven day regimens of either a tetracycline or erythromycin are generally preferred for uncomplicated infections, but ten days of a tetracycline is preferred for complications like acute pelvic inflammatory disease or epididymitis. For ocular or pulmonary infection in infants, a two to three week regimen of oral sulfonamide or erythromycin is preferred. for the treatment of concurrent N. gonorrhoeae and C. trachomatis, a tetracycline should be administered for at least five days.