In vivo interactions of rabbit enteropathogenic Escherichia coli O103 with its host: an electron microscopic and histopathologic study

• Published in: Microbes and infection Vol. 2; no. 1; pp. 5 - 16
• Main Authors: Heczko, Ursula, Abe, Akio, Finlay, B.Brett
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier SAS 2000; Amsterdam Elsevier; Paris
• Subjects: adherence; Animals; Bacterial diseases; Biological and medical sciences; Cecum - microbiology; Cecum - pathology; Cecum - ultrastructure; Colon - microbiology; Colon - pathology; Colon - ultrastructure; diarrhea; enteropathogenic Escherichia coli; Escherichia coli; Escherichia coli - pathogenicity; Escherichia coli - ultrastructure; Escherichia coli Infections - mortality; Escherichia coli Infections - pathology; Escherichia coli Infections - veterinary; Experimental bacterial diseases and models; Feces - microbiology; Female; Ileum - microbiology; Ileum - pathology; Ileum - ultrastructure; Infectious diseases; Inflammation - microbiology; Intestines - microbiology; Intestines - pathology; Intestines - ultrastructure; Medical sciences; Microscopy, Electron; Microscopy, Electron, Scanning; mucus; Mucus - microbiology; Mucus - secretion; pedestal; Peyer's patches; Peyer's Patches - microbiology; Peyer's Patches - pathology; Peyer's Patches - ultrastructure; Rabbits; Survival Analysis; Time Factors; Virulence; Weaning; Weight Gain; pedestal; Peyer's patches; enteropathogenic Escherichia coli; diarrhea; adherence; mucus; Animal model; Peyer patch; Colibacillosis; Escherichia coli; Diarrhea; Rabbit; Host agent relation; Lagomorpha; Adhesion; Infection; Pathogenicity; Vertebrata; Mammalia; Bacteriosis; Digestive diseases; Bacteria; Intestinal disease; Enterobacteriaceae
• ISSN: 1286-4579; 1769-714X
• DOI: 10.1016/S1286-4579(00)00291-4

Afamily of human and animal pathogens, including enteropathogenic and enterohemorrhagic
Escherichia coli (EPEC and EHEC), trigger formation of `attaching and effacing' lesions on cultured and intestinal epithelial surfaces. However, our understanding of these events in vivo is incomplete. To further study these interactions in a natural infection model, weaned rabbits were infected with rabbit enteropathogenic
E. coli O103 (REPEC O103), followed clinically, and infected tissues were evaluated by electron and light microscopy. Of the 36 rabbits challenged, morbidity and mortality were 65 and 23%, respectively. Twenty-four hours after infection, expression of fimbriae-like organelles was observed on the bacterial surface. Microvilli of ileal Peyer's patches (PP) became disorganized, and intestinal mucus secretion increased which coincided with intraluminal binding of the pathogen in the proximal colon. Forty-eight hours after infection, there was conspicuous lack of fimbriae-like organelle expression, while bacterial adherence preferentially occurred at the domed villi of PP. Seventy-two hours after infection, broad morphological heterogeneity was noted within pedestals beneath attached bacteria, including extended pseudopods. We conclude that REPEC O103 express surface organelles during initial exposure to the host, that the initial target sites of adherence are the domed villi of ileal PP, and that increased mucus secretion occurs during REPEC O103 infection. As well, extended pseudopod formation was demonstrated in vivo.