[Cholestyramine adsorbs Escherichia coli and Vibrio cholerae toxins by way of ion exchange mechanism]. / La cholestyramine fixe les toxines d'Escherichia coli et de Vibrio cholerae par une liaison ionique.

The use of cholestyramine in the treatment of enterocolitis is justified by its ability to fix the LT toxin of Vibrio cholerae and ETEC, the ST toxin of ETEC and the verotoxin of EHEC at the pH of intestinal fluid. To elucidate the nature of the ion-exchange mechanism in the binding of the toxins on the resin, we try to eluate the toxins with 0.1 M to 0.9 M NaCl solution at pH 7. Irrespective of their presence or absence in the different fractions, the biological activity of the toxins was assessed in cell culture and in the new-born mouse test. Desorption of the LT toxin from Vibrio cholerae is obtained with 0.6 M to 0.8 M of NaCl, with 0.3 M to 0.5 M of NaCl for the LT, 0.4 M to 0.5 M for the VT and 0.6 M for the TS toxins. The eluated toxins are biologically active; these facts demonstrate that the adsorption of toxin on cholestyramine result of a ion-exchange mechanism.

[Adsorption potency of 2 clays, smectite and kaolin on bacterial enterotoxins. In vitro study in cell culture and in the intestine of newborn mice]. / Pouvoir d'adsorption de deux argiles, la smectite et le kaolin sur des entérotoxines bactériennes. Etude in vitro sur culture cellulaire et sur intestin de souriceau nouveau-né.

The use of clays in the treatment of enterocolitis is justified by their ability to adsorb viruses, biliary acids and bacterial toxins secreted into the intestinal lumen. We have studied the in vitro inactivation of the LT toxins of Vibrio cholerae and E. coli, the ST toxin of ETEC and the verotoxin of EHEC. These various toxins were incubated with two types of clays, smectite and kaolin, to investigate the influence of dose, pH variations and the duration of contact of the clays with the toxins. Irrespective of their presence or absence in the supernatant, the biological activity of the toxins was assessed in cell culture and in the newborn mouse test. Both clays inactivated the LT toxin. Smectite was more efficient than kaolin as it was active immediately especially at the pH of intestinal chyme. The LT toxins were adsorbed on the clays by hydrogen bonding. This permitted the segregation of the toxins and prevented them from being fixed to the membrane receptors on the cells. The two clays were ineffective against the verotoxin of EHEC when the pH was alkaline although they were more efficient at acid pH. ST toxin of ETEC was slightly adsorbed by smectite and kaolin.

[Ability of cholestyramine to bind Escherichia coli and Vibrio cholerae toxins]. / Etude de l'aptitude de la cholestyramine à fixer les toxines d'Escherichia coli et de Vibrio cholerae.

Cholestyramine treatment of new born's infectious diarrhea has been shown to be effective. The study of in vitro binding of bacterial toxins from Vibrio Cholerae and from three strains of Escherichia coli suggest an ionic adsorption of the four toxins to this anion-exchange resin. This immediate binding is effective at the pH of intestinal fluid, therefore the protection of the enterocytes from the biological action of the toxins result of the toxins sequestering effect of the Cholestyramine.