First report of a livestock-associated methicillin-resistantStaphylococcus aureusST126 harbouring themecCvariant in Brazil

Staphylococcus aureusis 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-resistantS. aureus(MRSA) strains shortly after this drug became a therapeutic option. In this study, we report the genomic features of the firstmecC-mediated, beta-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 asmecC-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 amecChomolog gene in theorfX region associated with different penicillin-binding proteins. Moreover, genes encoding for efflux pump systems (arlR,mepR,LmrS,norA andmgrA), and antibiotic inactivation enzymes (blaZ andFosB) were also detected. Virulence analyses revealed that the strain harbours genes encoding for exoenzymes (aur, splA,splB andsplE), toxin (hlgA,hlgB,hlgC,lukD andlukE) 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 ofmecC-MRSA among animals and its impact on public health.

Automated summary

This study reports the genomic features of the first mecC-mediated, beta-lactam resistant MRSA strain associated with livestock in Brazil and the American continent. The strain was identified as sequence type 126 (ST126) and spa type t605, and harbored various genes related to antibiotic resistance and virulence. This research provides important epidemiologic and genomic information for understanding the origin and dissemination of mecC-MRSA among animals and its impact on public health.