Enteroinvasive
Escherichia coli
(EIEC) and
Shigella
spp cause bacillary dysentery in humans by invading and multiplying within epithelial cells of the colonic mucosa. Although EIEC and
Shigella share many genetic and biochemical similarities, the illness caused by
Shigella is more severe. Thus, genomic and structure-function molecular studies on the biological interactions of these invasive enterobacteria with eukaryotic cells have focused on
Shigella rather than EIEC. Here we comparatively studied the interactions of EIEC and of
Shigella flexneri with cultured J774 macrophage-like cells. We evaluated several phenotypes: (i) bacterial escape from macrophages after phagocytosis, (ii) macrophage death induced by EIEC and
S. flexneri, (iii) macrophage cytokine expression in response to infection and (iv) expression of plasmidial (pINV) virulence genes. The results showed that
S. flexneri caused macrophage killing earlier and more intensely than EIEC. Both pathogens induced significant macrophage production of TNF, IL-1 and IL-10 after 7 h of infection. Transcription levels of the gene invasion plasmid antigen-C were lower in EIEC than in
S. flexneri throughout the course of the infection; this could explain the diminished virulence of EIEC compared to
S. flexneri.
