Escherichia coli as a pathogen in dogs and cats

Certain strains of Escherichia coli behave as pathogens in dogs and cats ca using gastrointestinal and extra-intestinal diseases. Among the five known groups of diarrhoeagenic E. coli, namely enteropathogenic E. coli (EPEC), e nterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), shiga-toxin p roducing E. coli (STEC) and enteroaggregative E. coli (EAggEC), only EPEC a nd ETEC were clearly associated with enteric disease in young dogs. ETEC is olates from diarrhoeic dogs were found to be positive for the heat-stable e nterotoxins STa and STD but negative for heat-labile enterotoxin (LT). Cani ne ETEC were found to be different from those of other animals and humans b y their serotypes, production of alpha-haemolysin and adhesive factors and by the production of uncharacterized types of enterotoxins by some ETEC. Ca nine EPEC could be distinguished from EPEC of humans or other animals by th eir serotypes and by the ear-protein intimin which mediates intimate adhere nce of EPEC to intestinal mucosa cells. STEC were occasionally isolated fro m faeces of healthy and diarrhoeic dogs but their role in canine diarrhoea is not yet well known. EIEC and EAggEC were not reported to occur in dogs o r cats. Very little is known on diarrhoegenic E. coli in cats and further e pidemiological investigations on this subject are needed. Besides its role in gastro-intestinal infections, E. coli can cause infections of the urogen ital tract and systemic disease in dogs and cats. Extra-intestinal pathogen ic E. coli strains from dogs and cats belong to a limited number of serotyp es and clonal groups and are frequently found as a part of the normal gut f lora of these animals. Many of these E. coli strains carry P-fimbriae and p roduce alpha-haemolysin and a necrotizing cytotoxin (CNF1). Some of the fre quently isolated types of extra intestinal pathogenic E. coli from dogs, ca ts and humans were found to be highly genetically related but showed differ ences in their P-fimbrial adhesins which determine host specificity. Transm ission of extra-intestinal and enteral pathogenic E. coli between dogs and humans was reported. Further research is needed, however, to determine the role of dogs and cats as transmission vectors of pathogenic E. coli strains to other animals and humans. (C) Inra/Elsevier, Paris.