Genomic epidemiology of the opportunistic pathogen Staphylococcus coagulans from companion dogs.

Introduction. Staphylococcus coagulans (formerly Staphylococcus schleiferi subsp. coagulans) is a common commensal and opportunistic pathogen of companion dogs. It carries a range of antimicrobial resistance genes and is an occasional zoonotic pathogen.Hypothesis/Gap Statement. Despite the potential insight offered by genome sequencing into the biology of S. coagulans, few genomes are currently available for study.Aim. To sequence and analyse S. coagulans genomes to improve understanding of this organism's molecular epidemiology, antimicrobial resistance and bacterium-host interactions.Methodology. Twenty-five genomes of clinical isolates collected at a veterinary referral hospital in Scotland, UK, were sequenced with Illumina technology. These genomes were analysed by a series of bioinformatics tools along with 16 previously sequenced genomes.Results. Phylogenetic comparison of the 41 genomes shows that the current S. coagulans phylogeny is dominated by clades of closely related isolates, at least one of which has spread internationally. Ten of the 11 methicillin-resistant S. coagulans genomes in this collection of 41 encoded the mecA promoter and gene mutations that are predicted to render the isolates susceptible to penicillins in the presence of clavulanic acid, a feature only described to date in methicillin-resistant Staphylococcus aureus. Seven such isolates were from the current study and, in line with the genome-based prediction, all were susceptible to amoxicillin/clavulanic acid in vitro. S. coagulans shared very few highly conserved virulence-associated genes with Staphylococcus pseudintermedius, another common commensal and opportunistic canine pathogen.Conclusion. The availability of a further 25 genome sequences from clinical S. coagulans isolates will aid in better understanding the epidemiology, bacterial-host interactions and antimicrobial resistance of this opportunistic pathogen.