Animal contacts have been regarded as an emerging rout of Shiga toxin-producing Escherichia coli (STEC) infection in humans. Diarrhoeic and asymptomatic dogs have been recognised as a reservoir of atypical enteropathogenic Escherichia coli (EPEC), and STEC in some investigations. In this study E. coli isolates from 100 faecal samples of healthy (n=50) and diarrhoeic (n=50) dogs were screened by polymerase chain reaction (PCR) for the presence of determining virulence genes of STEC and EPEC pathotypes including stx and eaeA. The confirmed virulence-positive strains were subjected to antimicrobial susceptibility testing against 12 antibacterial using disc diffusion method. Resistance profiles were also determined for the STEC and EPEC strains. Ten isolates from 10 dogs (10%) were shown to possess at least one of the tested virulence genes. Six of these isolates (6%) harboured only the eaeA gene and were considered as EPEC. Four isolates (4%) were stx+ and regarded as STEC, of which two were stx+/eae+. The resistance was specially observed against penicillin, ampicillin, sulfomethoxazole, streptomycin and oxytetracyclin. Altogether, nine resistance profiles were observed among 10 isolates. In conclusion, dogs can act as a reservoir for EPEC and STEC strains, and close contacts of children with companion animals can be a potential risk factor in development of diarrhoea and haemolytic uremic syndrome. In rural areas shepherd dogs can also be a transient carrier of STEC strains that they may acquire from ruminants. To our knowledge this is the first study which reports the faecal shedding of STEC and EPEC from dogs in Iran.

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