Influence of colostrum on transepithelial movement of Escherichia coli 055.

The effect of colostrum on transepithelial migration of live Escherichia coli 055:B5:H7 in the neonatal calf intestine was determined by microbiological and microscopic investigations. Colostrum-deprived calves (2 to 6 h old) were given E. coli suspended in saline, E. coli suspended in colostrum, or E. coli in saline 1 h after colostrum. Twenty-four hours after exposure, tissues were collected for examination. Escherichia coli were numerous in mesenteric lymph nodes of calves given this organism in saline. Fewer were recovered from nodes of calves that received the bacteria in colostrum. Escherichia coli were not recovered from mesenteric lymph nodes of calves given colostrum before dosage with the organism. Electron microscopic studies of small intestines from calves that received E. coli in saline revealed bacterial attachment sites surrounded by exfoliation of microvilli. Bacteria appeared to enter epithelial cells by invagination of apical plasma membrane or dilation of apical tubules. Intracellular E. coli were enclosed in a surrounding membrane. The organisms were not observed adhering to or penetrating intestinal epithelium of calves that received E. coli in colostrum or 1 h after colostrum.