A rabbit model for bacterially induced preterm pregnancy loss: intervention studies with ampicillin-sulbactam.

We conducted experiments with a previously described rabbit model of Escherichia coli-induced preterm pregnancy loss. Does at 70% gestation were inoculated hysteroscopically with 0.2 ml of Escherichia coli (10(5) colony-forming units per milliliter) or saline solution. Animals were randomly assigned to either receive treatment with ampicillin-sulbactam (begun 1 to 2 hours before inoculation and continued for up to 7 days) or to receive no therapy. Animals were killed after delivery or after 7 days. Saline solution-inoculated animals had no pregnancy loss. Of the Escherichia coli-inoculated animals, those treated with ampicillin-sulbactam had significantly fewer deliveries, fewer positive cultures, and more live fetuses than the untreated animals (p less than or equal to 0.001). Cultures from multiple sites, amniotic fluid prostaglandin levels, and maternal progesterone levels were obtained, and the placenta, uterus, and fetal lung were histologically evaluated. In the second phase of the study, the Escherichia coli-inoculated animals were treated with ampicillin-sulbactam at one of three times: at inoculation or 2 or 4 hours after inoculation. The Escherichia coli-inoculated does treated with ampicillin-sulbactam at or before inoculation had significantly fewer deliveries, fewer positive cultures, and more live fetuses than the Escherichia coli-inoculated does in which treatment was delayed 4 hours (p less than or equal to 0.01).