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Objectives: MRSA is a known pathogen that affects horses. We investigated an equine MRSA isolate for potential antimicrobial resistance genes, classified the staphylococcal cassette chromosome mec (SCCmec) and identified the strain-specific dissemination in the horse community based on WGS.Methods: WGS, using short-read sequencing, and subsequent long-read sequencing by hybrid assembly, was conducted to obtain a complete genome sequence. Pairwise sequence alignment of relative SCCmec sequences and core-genome phylogenetic analysis were performed to highlight transmission routes of the SCCmec and MRSA strain-specific lineages.Results: In 2018, we isolated the MRSA JRA307 strain from the pus of a wound on a racehorse and the complete genome sequence suggests that it is a clinically relevant pvl-negative ST1-t127 MRSA that harbours both mecA and mecC on SCCmec-307. SCCmec-307 exhibited marked sequence identity to the previously reported SCCmec-mecC in the Staphylococcus sciuri GVGS2 strain isolated from cattle. The JRA307 mecC gene was classified as a mecC allotype of S. sciuri rather than that of Staphylococcus aureus.Conclusions: We demonstrated the complete genome sequence of equine isolate JRA307, which is a clinically relevant MRSA harbouring mecA and mecC on SCCmec-307. The finding of mecC MRSA suggests a possible SCCmec transmission between distinct staphylococcal species. To the best of our knowledge, this is the first report of mecC detection in Japan. [ABSTRACT FROM AUTHOR]

Summary: Aeromonas hydrophila and Aeromonas caviae adapt to saline water environments and are the most predominant Aeromonas species isolated from estuaries. Here, we isolated antimicrobial‐resistant (AMR) Aeromonas strains (A. hydrophila GSH8‐2 and A. caviae GSH8M‐1) carrying the carabapenemase blaKPC‐2 gene from a wastewater treatment plant (WWTP) effluent in Tokyo Bay (Japan) and determined their complete genome sequences. GSH8‐2 and GSH8M‐1 were classified as newly assigned sequence types ST558 and ST13, suggesting no supportive evidence of clonal dissemination. The strains appear to have acquired blaKPC‐2‐positive IncP‐6‐relative plasmids (pGSH8‐2 and pGSH8M‐1‐2) that share a common backbone with plasmids in Aeromonas sp. ASNIH3 isolated from hospital wastewater in the United States, A. hydrophila WCHAH045096 isolated from sewage in China, other clinical isolates (Klebsiella, Enterobacter and Escherichia coli), and wastewater isolates (Citrobacter, Pseudomonas and other Aeromonas spp.). In addition to blaKPC‐2, pGSH8M‐1‐2 carries an IS26‐mediated composite transposon including a macrolide resistance gene, mph(A). Although Aeromonas species are opportunistic pathogens, they could serve as potential environmental reservoir bacteria for carbapenemase and AMR genes. AMR monitoring from WWTP effluents will contribute to the detection of ongoing AMR dissemination in the environment and might provide an early warning of potential dissemination in clinical settings and communities. [ABSTRACT FROM AUTHOR]