Description d’un sérogroupe (0103) d’Escherichia coli entéropathogène chez le lapin au sevrage

Abstract

A partir de huit souches d'Escherichia coli (sérogroupe 0103) isolées de lapins atteints de diarrhée au sevrage, sept provoquent une dilatation de l'anse intestinale du lapin comparée à celle d'une souche positive humaine de contrôle n° 14 du CDC.Les auteurs inoculent l'estomac de 38 lapins, de 4 à 9 semaines, avec 10 x 1010 à 10u d'une souche du sérogroupe 0103. Diarrhée et mortalité (22 à 66 %) surviennent 4 jours après l'infection. L'autopsie révèle une typhlite grave, une multiplication excessive d'Escherichia coli de la flore, une élévatio� du pH au-dessus de 6,5, phénomènes observés dans la maladie naturelle. Au contraire, ils n'obtiennent aucun signe de maladie aux mêmes concentrations et par la même voie, avec une souche saprophyte de lapin et avec trois souches entéropathogènes du porc.Le rôle d'Escherichia coli dans la pathogénèse de la maladie n'est pas connu, mais à la .lumière de ces résultats, le mécanisme responsable est probablement du modèle choléra-like.En conclusion, les maladies diarrhéiques du lapin après le sevrage, en dehors du rôle non spécifique de l'endotoxine, pourraient être aussi reproduites par des souches spéciales entéropathogènes. Ces résultats n'éliminent pas le rôle prédisposant représenté par l'excès de bicarbonate dans l'estomac et par les coccidioses intestinales au moment du sevrage.Mots clés : Anse intestinale -Diarrhée -Escherichia coli entéropathogène -Lapin -Sevrage -Voie oro-gastrique. SUMMARYFrom eight strains of Escherichia coli (0103 serogroup) isolated from diarrheic rabbits after weaning, seven cause dilatation of intestinal loops in rabbits compared with positive human being control strain n° 14 from CDC.The authors inoculate the stomach of 38 rabbits, 4 to 9 weeks old, with 10 x 1010 to 1012 of one strain Escherichia Coli 0103 serogroup. Scouring and death (22 to 66 %) occur four days after infection .. Post mortem examination reveals severe typhlitis, excessive multipli cation of the Escherichia coli flora, elevation of the pH above 6,5, findings described in the natural disease. On the contrary, they do not obtain any ill effects, at the same concentrations, by the same way, with a saprophytic strain from rabbit and with three enteropathogenic strains from pigs. The role of Escherichia coli in the pathogenesis of the disease is unknown, but in the light of these results, the mechanism responsible is probably cholera-like model.In conclusion, diarrhoeic diseases on rabbits after weaning, without the non specific role of endotoxin could be also reproduced with particular enteropathogenic strains. These findings do not eliminate the predisposing role of the bicarbonate excess in the stomach and of the intestinal cocci diosis during the weaning period.

Scanning and transmission electron microscopic study of adherence of Escherichia coli O103 enteropathogenic and/or enterohemorrhagic strain GV in enteric infection in rabbits

“…Besides coccidiosis (9), rabbit diarrhea is often associated with E. coli infections (5,24). It has been shown experimentally that some strains belonging to serogroup 0103 are highly virulent for rabbits (2,17,26). Our previous study of an E. coli 0103 strain (GV) harboring an R plasmid of 117 kb (pREC-1) allowed us to establish the role of this plasmid in the colonization of the intestinal tract and in the pathogenicity of the strain (27).…”

“…In France, EPEC strains belonging to serogroup 015 rarely have been found up to now (4), but E. coli strains belonging to serogroup 0103 have been isolated in 30 to 40% of diarrheic rabbits (5, lla). It has been demonstrated previously that some strains of E. coli 0103 are highly virulent for rabbits (2,17,26). One of these strains (GV), isolated from an outbreak of diarrhea and harboring an R plasmid of 117 kb (pREC-1), was studied by Reynaud et al (27).…”

Biotypes and O serogroups of Escherichia coli involved in intestinal infections of weaned rabbits: clues to diagnosis of pathogenic strains

“…These enteric diseases are associated in each case with the proliferation of Escherichia coli in ileocecal contents of weaned rabbits. French as well as other researchers have isolated pathogenic E. coli strains with which they could reproduce the disease by feeding them to weaned rabbits (2,5,8,14,15,17). In 1984 and1985, an epidemiologic survey in 58 French rabbit-fattening farms with diarrhea problems led us to conclude that there was a peculiar frequency of E. coli strains belonging to serogroup 0103 (4).…”

Biotypes of enteropathogenic Escherichia coli strains from rabbits

“…Disease provoked by these strains seems to be widespread in industrial rabbit farms in Belgium (7). Renault et al (10) reported findings which suggest that other rabbit E. coli strains isolated in France are of the enterotoxigenic E. coli type.…”

“…Indeed, easily demonstrable bacteriological properties which could distinguish the enteropathogenic from nonpathogenic strains are not known: the EPEC strains do not produce heat-stable or heat-labile toxins nor are they invasive. Moreover, the strains belong to several O groups (7,9,10,12). Serotypings of rabbit E. coli strains have been reported by several other investigators as well (12), but these authors have not tried to assess the pathogenic importance and virulence of their strains.…”