Streptococcus canisis an animal pathogen that occasionally causes human infections. Isolates recovered from infections of animals (n= 78, recovered from 2000 to 2010 in three European countries, mainly from house pets) and humans (n= 7, recovered from 2006 to 2010 in Portugal) were identified by phenotypic and genotypic methods and characterized by antimicrobial susceptibility testing, multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), andemmtyping.S. canisisolates presented considerable variability in biochemical profiles and 16S rRNA. Resistance to antimicrobial agents was low, with the most significant beingtet(M)- andtet(O)-mediated tetracycline resistance. MLST analysis revealed a polyclonal structure of theS. canispopulation causing infections, where the same genetic lineages were found infecting house pets and humans and were disseminated in distinct geographic locations. Phylogenetic analysis indicated thatS. caniswas a divergent taxon of the sister speciesStreptococcus pyogenesandStreptococcus dysgalactiaesubsp.equisimilisand found evidence of acquisition of genetic material byS. canisfromS. dysgalactiaesubsp.equisimilis. PFGE confirmed the MLST findings, further strengthening the similarity between animal and human isolates. The presence ofemm-like genes was restricted to a few isolates and correlated with some MLST-based genetic lineages, but none of the human isolates could beemmtyped. Our data show thatS. canisisolates recovered from house pets and humans constitute a single population and demonstrate that isolates belonging to the main genetic lineages identified have the ability to infect the human host, providing strong evidence for the zoonotic nature ofS. canisinfection.

The equine disease strangles, which is characterized by the formation of abscesses in the lymph nodes of the head and neck, is one of the most frequently diagnosed infectious diseases of horses around the world. The causal agent, Streptococcus equi subspecies equi , establishes a persistent infection in approximately 10 % of animals that recover from the acute disease. Such ‘carrier’ animals appear healthy and are rarely identified during routine veterinary examinations pre-purchase or transit, but can transmit S. equi to naïve animals initiating new episodes of disease. Here, we report the analysis and visualization of phylogenomic and epidemiological data for 670 isolates of S. equi recovered from 19 different countries using a new core-genome multilocus sequence typing (cgMLST) web bioresource. Genetic relationships among all 670 S. equi isolates were determined at high resolution, revealing national and international transmission events that drive this endemic disease in horse populations throughout the world. Our data argue for the recognition of the international importance of strangles by the Office International des Épizooties to highlight the health, welfare and economic cost of this disease. The Pathogenwatch cgMLST web bioresource described herein is available for tailored genomic analysis of populations of S. equi and its close relative S. equi subspecies zooepidemicus that are recovered from horses and other animals, including humans, throughout the world. This article contains data hosted by Microreact.