Staphylococcus coagulans was originally described in 1990 as Staphylococcus schleiferi subsp. coagulans [1], and was subsequently classified as its own distinct species, S. coagulans, in 2020 [2]. As a primary commensal organism, S. coagulans can occasionally act as an opportunistic pathogen in companion dogs. It has been frequently isolated from the skin [3] and external ear canal [4] of healthy dogs, and is associated with external ear otitis [1,[3], [4], [5]] and pyoderma [4,[6], [7], [8]]. In humans, only six cases of S. coagulans infections have been reported, including surgical wound infection, endocarditis, left ventricular assist device infection, catheter-related bloodstream infection, and cellulitis [[9], [10], [11], [12], [13], [14]].

To date, few cases of human infections caused by S. coagulans suspected of having been transmitted from dogs have been reported [10,14]; however, to the best of our knowledge, no reports have clearly demonstrated transmission from dogs. Here, we report a case of an infectious lymphocele and bloodstream infection caused by S. coagulans. This study is the first to demonstrate, through phylogenetic analysis and whole genome sequencing of S. coagulans isolates, that the causative S. coagulans was transmitted from a pet dog to the patient.