ASCENDING GROUP-B STREPTOCOCCAL GENITAL-INFECTION IN THE RABBIT MODEL

OBJECTIVE: We investigated in a pregnant rabbit model the effects of i ntravaginal inoculation of type la group B streptqcocci and antibiotic intervention. STUDY DESIGN: We inoculated 10(4) to 10(6) cfu of type la group B streptococci into the upper vagina hysteroscopically at day 21 to 27 of a 31-day gestation. initially we studied the natural hist ory in 23 animals and then allocated the next 31 animals to receive ei ther no therapy or ampicillin-sulbactam intramuscularly beginning imme diately after inoculation. Outcomes were delivery, fever, positive cul tures for group B streptococci, any live fetuses, and maternal death. RESULTS: Without antibiotic treatment upper vaginal inoculation led to frequent complications, namely, fever in 44% (15/34), delivery in 41% (14/34), positive endometrial cultures in 47% (15/32),and positive bl ood cultures in 26% (7/27). Live fetuses were present in only 53% (18/ 34). Animals treated with antibiotics were significantly less likely t o have fever (p < 0.01), positive endometrial cultures (p < 0.01), or positive blood cultures (p = 0.03) and were more likely to have a live fetus (p = 0.04) than untreated animals were. CONCLUSION: Upper vagin al Inoculation with type la group B streptococci in the rabbit led to an ascending infection of the upper genital tract, causing serious adv erse outcomes in 40% with bacteremia in 26%. Early antibiotic interven tion significantly improved outcomes. The susceptibility of the rabbit to ascending perinatal group B streptococci infection makes it an app ealing model for further work pertinent io human disease.