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Category: Clinical Microbiology; Bacterial Pathogenesis
Tissue Tropism in Intestinal Colonization, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555817619/9781555813239_Chap17-1.gif /docserver/preview/fulltext/10.1128/9781555817619/9781555813239_Chap17-2.gifAbstract:
This chapter reviews the current understanding of the tissue tropism of bacterial pathogens, with a focus on virulent types of Escherichia coli. As surface-expressed organelles involved in bacterial attachment to the host mucosa, bacterial pili are likely to contribute to the tissue tropism of many bacterial pathogens. The enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) translocon directs the delivery of selected proteins into the internal milieu of the host cell. Loss of invasin-mediated integrin-binding activity leads to the colonization of other epithelial surfaces rich in mucus, suggesting that invasin is absolutely required for bacterial translocation into Peyer’s patches. Hence, similar to intimin, invasin modulates the site of initial mucosal colonization by an enteric pathogen. Tir from EPEC and the pili of uropathogenic E. coli (UPEC) allowed the gain of significant insight into the complexity of bacterial tissue tropism and its importance for pathogenesis. Importantly, the E. coli pathogens have shown that the specificity and affinity of bacterial surface attachment underlie the tissue tropism of mucosal pathogens and depend not only on timely expression of a specific bacterial adhesin but also on its binding affinity for a cognate host cell receptor and the tissue distribution and availability of the host receptor.
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Structural representations of the receptor-binding domains of the pilus adhesins, FimH (A) and PapGII (B). D-Mannose and Gb4 are included in both structural illustrations for comparison of the binding pockets. Reprinted from reference 40 with permission from Blackwell Publishing.
Structural representations of the receptor-binding domains of the pilus adhesins, FimH (A) and PapGII (B). D-Mannose and Gb4 are included in both structural illustrations for comparison of the binding pockets. Reprinted from reference 40 with permission from Blackwell Publishing.
(A) Transmission electron micrograph of A/E lesions in vivo in a child with chronic diarrhea. E. coli O114 serogroup was identified in stool samples and on the intestinal mucosa. Bar, 175 nm. (B) Schematic representation of the LEE-encoded EPEC/EHEC type III translocon.
(A) Transmission electron micrograph of A/E lesions in vivo in a child with chronic diarrhea. E. coli O114 serogroup was identified in stool samples and on the intestinal mucosa. Bar, 175 nm. (B) Schematic representation of the LEE-encoded EPEC/EHEC type III translocon.
Structural representation of the C-terminal region of intimin-α showing the Ig-like domains, D2 and D3, and the lectin-like module, D4.
Structural representation of the C-terminal region of intimin-α showing the Ig-like domains, D2 and D3, and the lectin-like module, D4.
Scanning electron micrograph of EHEC O157:H7-induced A/E lesions on FAE of a Peyer's patch in a human intestinal organ culture. Bar, 5 μm.
Scanning electron micrograph of EHEC O157:H7-induced A/E lesions on FAE of a Peyer's patch in a human intestinal organ culture. Bar, 5 μm.
Number of bacteria in mucosal scrapings obtained from different regions of the intestinal tract of rabbits inoculated with an EPEC strain 4 days previously
Number of bacteria in mucosal scrapings obtained from different regions of the intestinal tract of rabbits inoculated with an EPEC strain 4 days previously