Biotypes of enteropathogenic Escherichia coli strains from rabbits

Abstract

Forty-five enteropathogenic (enteropathogenic Escherichia coli-like) strains isolated in commercial rabbit farms were subdivided into four biotypes with the help of six carbohydrate fermentation tests, ornithine decarboxylase tests, and motility tests. E. coli strains which caused neonatal diarrhea in baby rabbits belonged to a single biotype, biotype 1, and displayed the same serotype antigens. Biotype 2 strains provoked diarrhea of variable severity in weaned rabbits and were also pathogenic for baby rabbits under laboratory conditions. Biotype 1 and biotype 2 strains resembled each other in many respects. Biotype 3 and biotype 4 (represented by a single strain) were highly pathogenic for weaned rabbits, but they provoked no symptoms or lesions in baby rabbits. Biotype 3 formed a homogeneous group of nonmotile strains which possessed the O15 antigen. Forty-two strains from nondiarrheic rabbits constituted a very heterogeneous collection of biotypes, most of which could easily be differentiated from the pathogenic types. Biotyping can be used to recognize rabbit pathogenic strains.

Biotype, serotype, and pathogenicity of attaching and effacing enteropathogenic Escherichia coli strains isolated from diarrheic commercial rabbits

“…Most strains belonged to biotypes 1 to 3, whereas none of the strains showed the fermentation pattern of biotype 4. The remaining 81 strains showed 14 fermentation patterns (biotypes 5 to 21) other than those described by Okerman and Devriese (10).…”

“…Moreover, small laboratories are capable of using this method. Okerman and Devriese (10) showed that biotyping can be used to recognize rabbit EPEC. They distinguished four different biotypes: biotype 1, which mainly affected suckling rabbits, and biotypes 2 to 4, which occuffed in diarrheic weaned rabbits.…”

“…The rate of mortality depends on the strains inoculated. Cross infection experiments showed that suckling rabbit strains may also attach to the intestinal mucosa of weaned rabbits and vice versa (10,13,17). In this case mortality is quite low.…”

“…Nevertheless, infection experiments confirmed the existence of AEEC strains with different tropisms for age group and intestinal compartment. AEEC isolated from suckling rabbits attach to the full length of the epithelial lining of the small and large intestines, which is followed by yellow diarrhea and high mortality (11,13), whereas strains isolated from weanling rabbits have been shown to attach only to the epithelium of the distal small intestine and the large intestine (2,3,10,15). The rate of mortality depends on the strains inoculated.…”

“…Biotyping. Biotyping was performed by the scheme of Okerman and Devriese (10). After primary isolation each strain was passaged twice on blood agar (tryptose blood agar base [Difco laboratories, Detroit, Mich.] with 5% [vol/vol] sheep blood).…”