Experimental epididymitis due to Chlamydia trachomatis in rats.

A new animal model of epididymitis due to Chlamydia trachomatis was developed. Adult male Wistar rats were inoculated in the vas deferens with C. trachomatis biovar mouse pneumonitis. After infection, C. trachomatis was recovered from the epididymides for up to 90 days. At day 30, organisms were also reisolated from the testes. Clinical findings included enlargement of infected epididymides and concurrent atrophy of the ipsilateral testes. Histological lesions in the epididymides consisted of pyogranulomatous inflammation, abscesses, and spermatic granulomas. Infection of the testis by C. trachomatis was associated with pyogranulomatous changes. In addition, testicular degeneration, characterized by moderate to severe loss of the germinal epithelium, was noted. Chlamydial antigen was detected within epithelial cells, intratubular macrophages, and macrophages in the stroma of the epididymis by immunoperoxidase staining. This rat model of chlamydial epididymitis appears to clinically and histopathologically mimic the human disease. This model offers the opportunity for further studies on the pathogenesis and sequelae of chlamydial epididymitis.