A case of sepsis caused by Streptococcus canis in a dog owner: a first case report of sepsis without dog bite in Japan

A 91-year-old dog-owning woman with a history of hypertension and femoral neck fracture consulted our hospital with fever and femur pain with redness. Laboratory test results showed leukocytosis with 85 % neutrophils and high values of C-reactive protein and procalcitonin. In addition, growth of Gram-positive streptococcus was observed in two independent blood culture sets. The isolated bacterium was identified as Streptococcus canis on the basis of biochemical properties and sequencing analyses of the 16S rRNA gene. The patient recovered completely without critical illness following prompt antimicrobial treatment with ceftriaxone. S. canis, a β-hemolytic Lancefield group G streptococcus, is in general isolated from various animal sources, but its isolation from a human clinical sample is extremely rare. Since β-hemolytic streptococci can cause severe infectious diseases such as necrotizing fasciitis, it is absolutely necessary to start antimicrobial treatment immediately. It is necessary to identify pathogenic bacteria carefully and to obtain information on a patient’s background, including history of contact with an animal, when S. canis is isolated.