Erysipelothrix rhusiopathiae is an important opportunistic bacterial pathogen of swine, turkeys, and sheep. It is distributed worldwide and has also been isolated from a wide variety of other species, including cattle, horses, dogs, cats, mice, rats, freshwater and saltwater fish, domestic poultry, marine mammals, and a variety of wild birds and mammals.
In turkeys, cyanotic skin lesions manifest most obviously as a blue comb. Other sequelae of E rhusiopathiae infection in turkeys include muscle petechiae and hemorrhaging, sudden death, and male infertility.
The incidence of erysipelas in poultry has increased in association with the change to cageless production systems, particularly in Europe.
E rhusiopathiae infection causes sporadic but serious disease in captive and wild marine mammals and has caused large-scale mortality events in northern wild ungulates.
As a zoonosis, E rhusiopathiae infection manifests as erysipeloid, a human condition characterized by localized skin infections and cellulitis. Erysipeloid is most likely to develop in people who work with infected animals, infected carcasses, or infected animal by-products. Other, less common manifestations of E rhusiopathiae infection in humans include a generalized cutaneous form and a septicemic form that can involve endocarditis.
In sheep, in addition to nonsuppurative polyarthritis, E rhusiopathiae can cause postdipping lameness, a severe lameness that results from infection caused by the penetration of bacteria through skin abrasions in the hoof or unhealed shearing wounds.
With time and repeated use, sheep dipping solutions can become contaminated with E rhusiopathiae and other bacteria. Discarding heavily contaminated dips is the best way to prevent infection and the associated lameness. Because dipping is now rarely used to control external parasites, nonsuppurative polyarthritis caused by E rhusiopathiae is now rare in sheep.
Etiology of Erysipelothrix rhusiopathiae Infection in Animals
The genus Erysipelothrix is subdivided into two major species: E rhusiopathiae and E tonsillarum. Erysipelothrix piscisicarius has also been described as a cause of low to moderate mortality rates in ornamental fish and of disease outbreaks in farmed turkeys. Other species (eg., E species 1 and E inopinata) are less well characterized and are rarely associated with disease.
At least 28 different Erysipelothrix serotypes are recognized, and pigs are considered to be susceptible to at least 15. Field cases of swine erysipelas are caused predominantly by E rhusiopathiae serotypes 1a, 1b, or 2.
E rhusiopathiae can survive in the soil for up to 5 weeks, and likely much longer; however, soil is not an effective growth medium. Soil and surface water contamination are routes of exposure. Subclinical carriers are the usual source of infectious organisms; however, the bacteria can also be introduced to animal production units by surface water runoff, wild mammals, wild birds, pets, and biting insects.
E rhusiopathiae has not been implicated as a cause of foodborne disease in humans.
E rhusiopathiae is a nonmotile, gram-positive, facultative anaerobic bacillus. It is catalase negative, oxidase negative, and coagulase positive; it is resistant to high salt concentrations; and it produces hydrogen sulfide on triple sugar iron media.
Colonies of E rhusiopathiae are either smooth or rough; rough colonies are slightly larger and have irregular edges. On agar media, colonies are clear, circular, nonhemolytic, and very small (0.1–1.5 mm in diameter) after 24 hours of incubation. The colonies increase in size after 48 hours and tend to develop a pale blue opacity. A zone of incomplete hemolysis also becomes evident around colonies.
E rhusiopathiae is very hardy, able to survive and grow in a wide range of pH values and environmental temperatures.
Many classes of commonly used disinfectants and/or compounds are considered to effectively inactivate E rhusiopathiae. Regardless of which disinfectant is used, removing organic matter by thorough cleaning before application improves effectiveness.
E rhusiopathiae is susceptible to beta-lactam antimicrobials (eg, penicillin, ampicillin) and to cephalosporin (ceftiofur), and it is resistant to sulfonamides, aminoglycosides, and vancomycin.
Key Points
E rhusiopathiae infection can be problematic in domestic poultry, particularly turkeys, in which it can cause death and male infertility.
Septicemia associated with E rhusiopathiae has been documented in captive marine mammals, and reports in wild marine and terrestrial mammals are increasing.
Postdipping lameness is a form of E rhusiopathiae infection, previously described in lambs and adult sheep, that is associated with antiparasitic dip treatments after skin wounds. This form of infection has become less common as a result of decreased use of sheep dips.
For More Information
Logue CM, Andreasen AB, Borst LB, et al. Other bacterial diseases. In: Swayne DE, ed. Boulianne M, Logue CM, McDougald LR, Nair V, Suarez DL, associate eds. Diseases of Poultry. 14th ed. Wiley Blackwell; 2020:995-1085.
Wang Q, Chang BJ, Riley TV. Erysipelothrix rhusiopathiae. Vet Microbiol. 2010;140(3-4):405-417.
Also see pet owner content regarding erysipelas in potbellied pigs.
