Pathophysiology and histopathology of group B streptococcal sepsis in Macaca nemestrina primates induced after intraamniotic inoculation: evidence for bacterial cellular invasion.

Four pregnant Macaca nemestrina dams at 140-145 days of gestation received an intraamniotic inoculation of group B streptococci (GBS). All four premature infants were born by cesarean delivery, were bacteremic at birth, and showed symptoms of GBS sepsis similar to infected human infants with early-onset disease. Three infants did not receive antibiotics and died of GBS sepsis by 10 h of age despite mechanical ventilation and fluids for blood pressure support. Penicillin treatment of the fourth infant prolonged survival and decreased the requirement for supportive therapy. Quantitative cultures and histopathology were done on all four infants. Transmission electron microscopy of lung tissue demonstrated GBS within membrane-bound vacuoles of type I and II alveolar epithelium and interstitial fibroblasts. This model should be useful for studying the early steps in the pathogenesis of early-onset GBS infections. GBS may enter alveolar epithelial cells to transit this barrier and ultimately disseminate via the blood-stream.