Microbiological, serological, and histopathological features of experimental Chlamydia trachomatis urethritis in chimpanzees.

A laboratory-passaged genital strain of Chlamydia trachomatis and two unpassaged genital strains from patients with nongonococcal urethritis were inoculated intraurethrally into three young male chimpanzees. Chlamydia were recovered from the urethra of two animals and specific antibody responses were detected in all of them. Furthermore, a urethral polymorphonuclear leucocyte response, but not an overt discharge, occurred in all the chimpanzees about 1-2 weeks after inoculation. None of these events occurred in a chimpanzee inoculated with medium only. At necropsy three months after inoculation the submucosa of the urethra of one chimpanzee was densely infiltrated with small round cells. This suggests that a similar chronic lymphocytic response may occur in human chlamydial infection of the urethra.