[Comparative study of adherence to rabbit enterocytes, presence of colonization factors CFA/I and CFA/II and toxinogenesis of 55 strains of Escherichia coli]

The lipopolysaccharide from Escherichia coli O127:B8 induces inflammation and motility disturbances in rabbit ileum

<p>The aim of this work was to evaluate the effects of lipopolysaccharide (LPS) from <em>Escherichia coli </em>O127:B8 on the expression of toll-like receptor 4 (TLR4), the histology, and motor function in rabbit ileum. Rabbits were injected intravenously with saline or LPS (100 μg/kg, 2 h). The mRNA expression and localization of TLR4 were determined by reverse transcriptase-PCR and immunofluorescence, respectively. Histological damage induced by LPS was evaluated in sections of ileum stained with haematoxylin and eosin. Contractility studies of ileum were performed in an organ bath. The mRNA expression of TLR4 decreased in the muscular but not in the mucosal layer of rabbits treated with LPS. TLR4 was localised in both the mucosal and muscular layers of rabbit ileum. LPS induced intestinal inflammation and altered the spontaneous contractions and the serotonin-, acetylcholine- and KCl-induced contractions. In conclusion, LPS from <em>E. coli </em>O127:B8 induced a decrease in the mRNA expression of TLR4, an inflammatory response, and changes in the contractility of rabbit ileum.</p>

Identification of a human erythrocyte receptor for colonization factor antigen I pili expressed by H10407 enterotoxigenic Escherichia coli

We have identified a receptor for colonization factor antigen I (CFA/I) pili in human erythrocyte membranes. Erythrocyte binding assays, using whole organisms, suggested that the CFA/I receptor was a glycoprotein containing important sialic acid moieties. Subsequently, human erythrocyte membranes were extracted with lithium diiodosalicylate to obtain a soluble glycoprotein fraction from which to isolate receptors. The extracted material caused agglutination of the CFA/I+ but not the CFA/I- organisms at a protein concentration of 0.5 mg/ml. The CFA/I receptor was identified in iodinated extract by an affinity isolation procedure, using whole bacterial cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography of the washed, extract-coated H10407 CFA/I+ organisms revealed a band with an apparent molecular weight of 26,000 which was present in the original extract but was not observed on extract-coated H10407 CFA/I- bacteria. The addition of purified CFA/I pili reduced binding of the 26,000-molecular-weight receptor to CFA/I+ bacteria. The CFA/I-specific receptor species also bound to wheat germ agglutinin-agarose. This observation supported the suggestion that the CFA/I receptor identified in this report is a sialoglycoprotein.

[Direct detection in diarrheal stools of Escherichia coli adhesion factors CFA/I, CFA/II and E8775 by the india ink immune reaction]

An India ink immune reaction was used for the direct detection, in diarrhoeal stools, of Escherichia coli possessing the CFA/I, CFA/II and E8775 fimbriae. With this method, a presumptive diagnosis of enterotoxigenic E. coli (ETEC) can rapidly be made. Staining required the bivalency of rabbit anti-fimbriae IgG; the F(ab')2 fragment was necessary. The reaction was impossible with purified Fab fragment. A comparative study of this technique and detection by culture of ETEC strains showed good correlation when the India ink immune reaction was performed at the beginning of infection.