Permeation of human chorioamniotic membranes by Escherichia coli in vitro.

Objective: Our goal was to study the permeation of Escherichia coli through human chorioamniotic membranes in vitro.
Study Design: Medium was placed in two compartments separated by chorioamniotic membranes obtained from six cesarean sections at term. The compartment faced by the chorion was inoculated with E. coli. Both compartments were sampled over 12 hours for observation of bacterial growth. Controls were performed without membranes.
Results: In the compartment that was inoculated, concentration of E. coli increased from 10(6) to 10(10) colony-forming units per milliliter. In the compartment faced by amnion, bacterial growth was observed after 6 hours and reached 10(3) colony-forming units per milliliter. Permeation of E. coli was confirmed histopathologically. The change of glucose and lactate was linear. In the controls the concentration of E. coli increased to 10(7) (p < 0.001).
Conclusions: E. coli organisms permeate viable chorioamniotic membranes. The membranes constitute a weak barrier against ascending infection and do not inhibit bacterial growth.