Pathogenic Escherichia coli strains from dogs and cats : Clinical and bacteriological data on necrotoxigenic and adhesin-positive Escherichia coli strains

The purpose of this study was to characterize 25 necrotoxigenic Escherichia coli type 1 (NTEC1), one necrotoxigenic E. coli type 2 (NTEC2) and 16 non-necrotoxigenic E. coli isolated, between 1979 and 1993, from feces, intestinal content or internal organs of dogs and cats using an uniform and standardized typing scheme, as previously described on NTEC1 and NTEC2 isolates from cattle, humans and pigs. The results obtained by colony hybridization and PCR on the NTEC1 isolates were homogeneous: eighteen NTEC1 isolates harboured prs- and sfa/foc-related DNA sequences; five NTEC1 isolates harboured sfa/foc-related DNA sequences; one NTEC1 isolate harboured prs-related DNA sequences; and one was negative. The only NTEC2 isolate was also negative. Only a few NTEC1 isolates were positive for f17-, afa- or cdt-related DNA sequences. All NTEC1 and the NTEC2 isolates were haemolytic on blood agar and were resistant to the bactericidal activity of the serum. A very few produced an aerobactin or a colicin. The strains belonged to various serogroups and many could not be identified with the immunsera used. On the other hand all but one NTEC1 isolates belonged to biotype 9. The most typical profile : two of them harboured pap/prs- and sfa/foc-related DNA sequences; ten harboured pap/prs-related DNA sequences; and four, other DNA sequences. The results of the phenotypic assays were also more heterogeneous. NTEC1 strains were isolated from essentially young puppies and kitties ( 3 months for 16 out of 22), with sometimes older animals (up to 12 years). The digestive pathologies were non haemorrhagic diarrhoea/enteritis essentially. When haemorrhagic diarrhoea/enteritis were observed, other infectious agents were present or strongly suspected (parvovirus, Salmonella). Extraintestinal pathologies were septicaemic or systemic colibacillosis, with one case of necrohaemorrhagic metritis. NTEC1 and non-NTEC were not frequently antibiotic resistant. The most frequent resistant were to ampicillin, trimethoprim/sulfonamides and neomycin.