Erysipelothrix rhusiopathiae: an occupational pathogen.

Erysipelothrix rhusiopathiae is a nonsporulating, gram-positive, rod-shaped bacterium which was identified more than 100 years ago as the etiologic agent of swine erysipelas. Since then, it has been found to cause infection in several dozen species of mammals and other animals. Humans become infected through exposure to infected or contaminated animals or animal products. By far the most common type of human infection is a localized, self-limited cutaneous lesion, erysipeloid. Diffuse cutaneous and systemic infections occur rarely. Approximately 50 cases of endocarditis have been reported; all but one recent case have involved native valves. The organism may be isolated from biopsy or blood specimens on standard culture media. It is identified by morphology, lack of motility, and biochemical characteristics; identification may be confirmed by the mouse protection test. It is susceptible to penicillins, cephalosporins, erythromycin, and clindamycin, but it is often resistant to many other antibiotics, including vancomycin, a drug frequently used in empiric therapy for infections due to gram-positive bacteria.