Chlamydial salpingitis in female guinea pigs receiving oral contraceptives.

Female guinea pigs were given daily doses of a combination of oral contraceptive (OC) agents, consisting of mestranol and norethynodrel suspended in sesame oil or distilled H2O, and were infected in the genital tract with the chlamydial agent of guinea pig inclusion conjunctivitis (GPIC). Counts of chlamydial inclusions in cells of vaginal smears collected during infection, showed prolongation and enhancement of infection in OC-treated animals as compared with controls. Appearance of IgG and IgA antibodies to GPIC in genital secretions, as determined by enzyme-linked immunosorbent assay (ELISA), was also delayed in OC-treated animals as compared with controls. OC-treated infected animals were killed on days 15 and 43, and gross pathological evidence for ascending infection culminating in salpingitis was found in all of five and four of five animals, respectively. On the other hand, among untreated infected controls on each sacrifice day, only one of five animals had any evidence for ascending infection. Chlamydiae were detected by light and electron microscopy in fallopian tube tissue collected on day 15 following OC-treatment but not in tissue from control animals.