Adherence to and penetration of cultured cells by an invasive strain of Escherichia coli: an ultrastructural study.

The penetration process of an enteroinvasive strain of Escherichia coli 0124 into HEp-2 cells has been studied by electron microscopy. Bacteria penetrated into cultured cells by a phagocytosis-like mechanism, and multiplied within the vacuoles as well as in the cytoplasmic matrix. On the whole, the infection cycle of EIEC appeared to be similar to that described for Shigella. The stain examined has also been found to elaborate a 40 nm-thick glyocalix, which is probably involved in the recognition of host surface receptors and therefore in the attachment of microorganisms to the cell membrane.