Organ culture of rabbit ileum as a model for the investigation of the mechanism of intestinal damage by enteropathogenic Escherichia coli.

Organ culture of rabbit ileum has been established as a model for the investigation of the mechanism of intestinal damage by enteropathogenic Escherichia coli (EPEC). Loops of rabbit ileum were filled in vivo with saline, non-enteropathogenic P-fimbriate E coli (PFEC), or EPEC. After 45 minutes the loops were washed, then mucosal biopsies were taken and cultured for up to 48 hours. The earliest changes discernable by electron microscopy were observed at 18 hours postinfection, at which time EPEC were closely adherent to the surface of enterocytes at the base of microvilli, some of which were elongated. By 24 hours postinfection there were large areas of brush border effacement with pedestal formation around the EPEC. No such damage was seen in biopsies from the control loops (saline, PFEC), and intracellular ultrastructure was extremely well preserved in all preparations for up to 48 hours. While there were no differences at eight hours, biochemical analyses at 24 hours postinfection showed a marked increase in the release of brush border enzymes into the culture medium from EPEC-infected explants compared to explants from the control loops. These findings provide morphological and biochemical evidence for damage to the microvillus membrane by EPEC, and validate organ culture of rabbit ileum as a model for the investigation of EPEC-pathogenicity.