Nine weaned calves (6 to 8 weeks of age) were given 1010 CFU of a five-strain mixture of enterohemorrhagic Escherichia coli O157 : H7 by oral-gastric intubation.
After an initial brief period of pyrexia in three calves and transient mild diarrhea in five calves, calves were clinically normal throughout the 13-to 27-day study.
The population of E. coli O157 : H7 in the feces decreased dramatically in all calves during the first 2 weeks after inoculation.
Thereafter, small populations of E. coli O157 : H7 persisted in all calves, where they were detected intermittently in the feces and rumen contents.
While withholding food increased fecal shedding of E. coli O157 : H7 by 1 to 2 log10/g in three of four calves previously shedding small populations of E. coli O157 : H7, the effect of fasting on fecal shedding of E. coli O157 : H7 was variable in calves shedding larger populations.
At necropsy, E. coli O157 : H7 was not isolated from sites outside the alimentary tract.
E. coli O157 : H7 was isolated from the forestomach or colon of all calves at necropsy.
Greater numbers of E. coli O157 : H7 were present in the gastrointestinal contents than in the corresponding mucosal sections, and there was no histologic or immunohistochemical evidence of E. coli O157 : H7 adhering to the mucosa.
In conclusion, under these experimental conditions, E. coli O157 : H7 is not pathogenic in weaned calves, and while it does not appear to colonize mucosal surfaces for extended periods, E. (...)
Mots-clés Pascal : Escherichia coli, Enterobacteriaceae, Bactérie, Souche pathogène, Bétail, Bovin, Artiodactyla, Ungulata, Mammalia, Vertebrata, Infection, Etude expérimentale, Appareil digestif, Dénombrement, Colonisation, Médecine vétérinaire, Fèces, Persistance, Rumen, Excrétion, Intestin, Relation hôte agent, Inoculation, Souche entérohémorragique
Mots-clés Pascal anglais : Escherichia coli, Enterobacteriaceae, Bacteria, Pathogen strain, Livestock, Bovine, Artiodactyla, Ungulata, Mammalia, Vertebrata, Infection, Experimental study, Digestive system, Enumeration(counting), Colonization, Veterinary medicine, Feces, Persistence, Rumen, Excretion, Gut, Host agent relation, Inoculation
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 97-0076507
Code Inist : 002A05B10. Création : 21/05/1997.