Significant reduction in inflammatory response in the macaque model of chlamydial pelvic inflammatory disease with azithromycin treatment.

We inoculated 45 female macaques in the cervix with Chlamydia trachomatis once weekly for 5 weeks and randomly assigned them to treatment with doxycycline (n=12), azithromycin (n=12), or placebo (n=21). At hysterectomy, cervical cultures remained positive in 12 of 21 placebo-treated monkeys, versus 0 of 12 doxycycline- or azithromycin-treated monkeys (P<.01); cervical ligase chain reaction remained positive in 15 placebo-, 1 doxycycline-, and 0 azithromycin-treated monkeys. Tubal swabs remained positive in 3 placebo-, 1 doxycycline-, and 0 azithromycin-treated monkeys. Immunopathologic damage was moderate to widespread in upper and lower reproductive-tract tissues from placebo- and doxycycline-treated monkeys but were significantly reduced in azithromycin-treated monkeys. Transforming growth factor- beta was also significantly less prevalent in azithromycin-treated monkeys. Azithromycin treatment dramatically reduced the inflammatory response and was highly effective in eradicating C. trachomatis from the lower and upper reproductive tract (12/12), compared with doxycycline (7/12) and placebo (3/21).