[Pathogenic mechanisms of enterotoxigenic Escherichia coli in guinea pigs].
OBJECTIVE
To explore the pathogenic mechanisms of enterotoxigenic Escherichia coli (ETEC) in guinea pigs.


METHODS
Pathological examination of the intestines was performed in ETEC-infected guinea pigs, and the intracellular free Ca2+ concentration, cytoplasmic pH, cell membrane potential and mitochondria membrane potential were determined immunohistochemically and by means of flow cytometry.


RESULTS
The guinea pigs were sensitive to the human-origin ETEC, which caused pathological changes in the small intestines such as edema, hyperemia and lymphocyte infiltration, but no bacteria invasion into the epithelial cells was identified. Under transmission electron microscope, the ileal epithelial cells were shown with vacuolar degeneration and evidence of mitochondrial proliferation; heat-labile (LT) and heat-stable (ST) toxins pervaded in the ileal tissue, resulting in significant increase of intracellular free Ca2+ concentration, cytoplasmic pH value and cell membrane potential, with concomitance of significant decrease in mitochondrial membrane potential.


CONCLUSIONS
ETEC disturbs the absorption and secretion functions of the intestinal epithelial cells, and induces extensive inflammation in the small intestines of guinea pigs. Besides their action on intestinal epithelial cells, LT and ST also affect the myocytes in the muscularis, and their action sites and mechanism might be similar. ETEC-induced diarrhea is correlated with excessive water excretion from the cells.
Chen
Qing
Q
Department of Epidemiology, First Military Medical University, Guangzhou 510515, China. qingchen@fimmu.com
Yu
Shou-yi
SY
Shen
Hong
H
Wang
Ya-xian
YX
Wu
Min
M
D000818:Animals; D001427:Bacterial Toxins / Q000032:analysis; D002118:Calcium / Q000378:metabolism; D004768:Enterotoxins / Q000032:analysis; D004926:Escherichia coli / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D029968:Escherichia coli Proteins; D005260:Female; D006168:Guinea Pigs; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C034151:heat stable toxin (E coli); C027538:heat-labile enterotoxin, E coli; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium