AimsTo determine the prevalence of cross-species sharing of Escherichia coli between healthy dogs and humans living in the same household. Methods and ResultsTwo faecal E.coli isolates from 25 healthy dog-owner pairs and 16 healthy control humans were tested using three fingerprinting methods. The prevalence of within-household sharing of E.coli was 4, 8 and 8% using pulsed-field gel electrophoresis, randomly amplified polymorphic DNA and enterobacterial repetitive intergenic consensus-PCR analyses respectively. Within-household bacterial sharing was more prevalent than across-household sharing (P<005). According to questionnaire analyses avoiding the dog-owner behaviours such as allowing a dog to kiss or lick the owner's face, sharing people food with dog and feeding it raw meat may decrease the chance of cross-species E.coli sharing. ConclusionsDirect contact between humans and dogs and environmental reservoirs may be important routes for cross-species sharing of bacteria. Good personal hygiene and appropriate veterinary care for pets can minimize this risk. Significance and Impact of the StudyDue to the importance of canine pathogenic E.coli reservoir hypothesis, close contacts between humans and dogs raises public health concerns. Determining the rate of cross-species bacterial sharing and confirm its accuracy by different fingerprinting techniques will help to find ways for reducing the economic impact of E.coli infections. This study support claims that public health concerns regarding the cross-species sharing of E.coli are warranted but this risk is minimal.