PREVALENCE AND CHARACTERISTICS OF ESCHERICHIA COLI AND SALMONELLA SPP. IN THE FECES OF WILD URBAN NORWAY AND BLACK RATS (RATTUS NORVEGICUS AND RATTUS RATTUS) FROM AN INNER-CITY NEIGHBORHOOD OF VANCOUVER, CANADA

Abstract Although rat feces are widely suspected to be a source of pathogenic bacteria, few investigators have studied fecal pathogens in rats. We investigated the prevalence and characteristics of Escherichia coli and Salmonella spp. in Norway and black rats (Rattus norvegicus and Rattus rattus, respectively) from an urban neighborhood of Vancouver, Canada, collected September 2011–August 2012. Colon content was cultured for E. coli and Salmonella spp. and screened for the seven most-common enteropathogenic Shiga toxin–producing E. coli (STEC) serotypes by PCR. Isolates were tested for antimicrobial resistance and Salmonella isolates were serotyped. We detected E. coli in 397/633 (62.7%) urban rats. Forty-one of 397 (6.5%) E. coli isolates were resistant to ≥1 antimicrobial while 17 (4.3%) were multidrug resistant (including two isolates demonstrating extended-spectrum β-lactamase resistance). Ten of 633 (1.6%) urban rats were carrying STEC serotypes including O145, O103, O26, and O45. Norway rats were m...