Escherichia coli infection in mice and impaired fetal development.

Investigations were undertaken, using the mouse as an animal model, to study the effect of Escherichia coli on fetal development. The i.v. injection of 7.5 X 10(6) bacteria, originally obtained from a suspected case of human pyelonephritis, caused only a mild and transient disturbance of maternal health but caused severe fetal wastage. Groups of mice were examined 4, 7 and 11 days after infection and the numbers of organisms were determined in the spleen, liver, kidneys, placentas and resorptions. From the findings obtained, it was concluded that the Esch. coli grew preferentially in the placentas. By the 7th day the placentas showed marked degenerative and necrotic changes and the bacteria could be recovered from the majority of fetuses at this time. Histologically, no significant changes were seen in the spleen, liver and kidneys. As a result of these findings in an animal model, and taking into consideration the observations of other workers, it is suggested that coliform bacteraemia in human pregnancies may also cause infections of the placenta and bring about abortion or premature delivery.