Characterization and identification of Erysipelothrix rhusiopathiae isolated from an unnatural host, a cat, with a clinical manifestation of depression.

Erysipelothrix rhusiopathiae is pathogenic for humans, many domestic animals and wild birds, but infectious cases with clinical symptoms in cats have not been reported. E. rhusiopathiae was recovered from a 4-month Russian blue breed cat with a very poor body condition score of 1 (BCS: 1/5). The isolate was typed as serotype 2b. Mice experimentally infected with the clinical isolate of E. rhusiopathiae through subcutaneous or intraperitoneal routes survived, and the organism was recovered from the spleen and synovial and pericardial fluids. Cats experimentally inoculated with the isolate either orally or subcutaneously survived but commonly exhibited depression and emaciation together with localized erythemal lesion of the skin accompanied by purulent ocular discharge. On hematological analysis, the number of total white blood cells was high compared with that in normal cats. Histological examination revealed congestion and moderate inflammation with focal necrosis. This observation may provide insight on E. rhusiopathiae infection in cats with the possible epidemiological significance and implications as a potential source of infection to other animals and humans.