First report of a livestock-associated methicillin-resistant Staphylococcus aureus ST126 harbouring the mecC variant in Brazil.

Staphylococcus aureus is a versatile and highly adaptable pathogen associated with a wide range of infectious diseases in humans and animals. In the last decades, concern has increased worldwide due to the emergence and spread of methicillin-resistant S. aureus (MRSA) strains shortly after this drug became a therapeutic option. In this study, we report the genomic features of the first mecC-mediated, β-lactam resistant MRSA strain associated with livestock in Brazil and in the American continent. Three clonally related phenotypic MRSA isolates originated from a dairy herd were confirmed by polymerase chain reaction as mecC-harbouring MRSA isolates. Whole-genome sequencing was performed by Illumina Miseq platform. Downstream analyses showed that the strain was identified as the sequence type 126 (ST126) and spa type t605. In silico analysis revealed a mecC homolog gene in the orfX region associated with different penicillin-binding proteins. Moreover, genes encoding for efflux pump systems (arlR, mepR, LmrS, norA and mgrA), and antibiotic inactivation enzymes (blaZ and FosB) were also detected. Virulence analyses revealed that the strain harbours genes encoding for exoenzymes (aur, splA, splB and splE), toxin (hlgA, hlgB, hlgC, lukD and lukE) and enterotoxin (sea). The epidemiologic and genomic information provided by this study will support further epidemiological and evolutionary investigations to understand the origin and dissemination of mecC-MRSA among animals and its impact on public health.