Antiseptic Susceptibility Profiles of Canine Pyoderma-associated Staphylococci in Japan: First Identification of Plasmid-borne smr in Staphylococcus coagulans

Manami Tsunoi^1*Manabu Takiguchi²Emi Ashida²Kazuki Harada³Keita Iyori²Koki Shimizu⁴

• ¹Core Research Facilities, Research Center for Medical Sciences, The Jikei University School of Medicine, Tokyo, Japan
• ²1sec. Co., Ltd, Kanagawa, Japan
• ³Joint Graduate School of Veterinary Sciences, Tottori University, Tottori, Japan
• ⁴Department of Applied Mathematics, Tokyo University of Science, Tokyo, Japan

International guidelines recommend the use of antiseptics, such as chlorhexidine, to treat canine pyoderma. However, data on the antiseptic susceptibility of its primary causative agents, Staphylococcus pseudintermedius and S. coagulans, in Japan are limited. In this study, we performed antiseptic susceptibility testing and polymerase chain reaction screening for antiseptic resistance-associated genes in these species. Among the examined isolates, we obtained low minimum inhibitory concentrations for the assessed antiseptics, with some inter-strain variations. We identified one smr-positive S. coagulans isolate, SC18, which represents only the second global report and the first from Japan. Phylogenetic analysis using publicly available genome data revealed that SC18 is a strain of the major lineage of S. coagulans. To investigate its genetic context, we performed hybrid genome sequencing of SC18 and demonstrated, for the first time, that smr is a plasmid-borne gene in S. coagulans. This plasmid was identified in a human-derived S. epidermidis strain (KSE124-2) in Japan, indicating the likelihood of plasmid-mediated interspecies transmission between humans and their companion animals. These findings highlight the need for continued surveillance of antiseptic resistance-associated genes, which may contribute to reduced phenotypic susceptibility and, thus, represent a potential public health concern.