Erysipelothrix rhusiopathiae was first isolated by Koch in 1876. E. rhusiopathiae is the only named species in the genus Erysipelothrix. In the history of this organism there have been as many as three species distinguished, but in 1966 it was decided that all these strains belonged to one species. The official name the organism was given was Erysipelothrix rhusiopathiae, which literally means “erysipelas thread of red disease.” There is more variation in the rhusiopathiae strains than is usually found within a single species therefore more tests need to be completed to determine if the genus Erysipelothrix should indeed contain more than one species.
Erysipelothrix rhusiopathiae is a slender gram positive nonsporulating rod that is a facultative anaerobe. Growth of this organism is improved by 5-10% CO2. This organism can be found in a variety of configurations such as in short chains, in pairs, in a “V” configuration or even grouped randomly. These gram positive organisms can appear gram negative because of their tendency to decolorize rapidly.
Erysipelothrix rhusiopathiae causes infections within humans as well. There are three clinical categories for the human disease caused by this organism. A localized cutaneous form (most common), a generalized cutaneous form, and a septicemic form (associated with the heart disease endocarditis). Human infections are primarily found as a result of occupational hazards such as those who handle fish. This organism has never been reported as causing a disease in fish but grows and persists for long periods of times in the exterior of these animals. This fact puts those who handle fish at high risk of contracting this organism. Erysipelothrix rhusiopathiae primarily enters its host via scratches or puncture wounds on the surface of the skin. A patient infected by this organism with the localized cutaneous form commonly exhibit symptoms of a throbbing itching pain and swelling on the finger or part of hand infected. Infections can be easily treated by antibiotic therapy.
A species which causes swine erysipelas, human erysipeloid, non-suppurative polyarthritis in lambs, and septicaemia in mice, and commonly infects fish handlers; it is the type species of the genus Erysipelothrix. Synonym: Erysipelothrix insidiosa.