Erysipelothrix rhusiopathiae (formerly E. insidiosa) are thin, gram-positive, capsulated, nonsporulating, nonmotile, microaerophilic bacilli with worldwide distribution; they are primarily saprophytes.
E. rhusiopathiae may infect a variety of animals, including shellfish, fish, birds, and mammals (especially swine), and insects. In humans, infection is chiefly occupational and typically follows a penetrating wound in people who handle edible or nonedible animal matter (eg, infected carcasses, rendered products [grease, fertilizer], bones, shells). Most commonly, patients handle fish or shellfish or work in slaughterhouses. Infection can also result from cat or dog bites. Nondermal infection is rare, usually occurring as septic arthritis or infective endocarditis.
Within 1 week of injury, a characteristic raised, purplish red, nonvesiculated, indurated, slowly evolving localized cellulitic rash on the hand (erysipeloid) appears, accompanied by itching and burning. Local swelling, although sharply demarcated, may inhibit use of the hand, the usual site of infection. The lesion’s border may slowly extend outward, causing discomfort and disability that may persist for 3 weeks. Localized erysipelothricosis is usually self-limited.
Regional lymphadenopathy occurs in about one third of cases. Erysipelothricosis rarely becomes generalized cutaneous disease, which is characterized by purple skin lesions that expand as the lesion’s center clears, plus bullous lesions at the primary or distant sites.
Bacteremia is rare and is more often a primary infection than dissemination from cutaneous lesions. It may result in septic arthritis or infective endocarditis, even in people without known valvular heart disease. Endocarditis tends to involve the aortic valve, and the mortality rate and percentage of patients needing cardiac valve replacement are unusually high. Rarely, central nervous system, intra-abdominal, and bone infections occur.
Culture of a full-thickness biopsy specimen is superior to needle aspiration of the advancing edge of a lesion because organisms are located only in deeper parts of the skin. Culture of exudate obtained by abrading a florid papule may be diagnostic. Isolation from synovial fluid or blood is necessary for diagnosis of erysipelothrical arthritis or endocarditis. E. rhusiopathiae may be misidentified as lactobacilli.
Polymerase chain reaction amplification may aid rapid diagnosis of erysipelothricosis. Rapid diagnosis is particularly important if endocarditis is suspected because treatment of endocarditis due to E. rhusiopathiae is often different from the usual empiric treatment of gram-positive bacillary endocarditis (eg, E. rhusiopathiae is resistant to vancomycin, which is typically used).
For localized cutaneous disease, usual treatment is one of the following, given for 7 days:
Cephalosporins are also effective. Daptomycin and linezolid are active in vitro and may be considered if patients are very allergic to beta-lactams. Tetracyclines and macrolides may no longer be dependable.
E. rhusiopathiae are resistant to sulfonamides, aminoglycosides, and vancomycin.
Severe diffuse cutaneous or systemic infection is best treated with one of the following:
Endocarditis is treated with penicillin G for 4 to 6 weeks. Cephalosporins and fluoroquinolones are alternatives. Vancomycin is often used empirically for the treatment of gram-positive bacillary endocarditis; however, E. rhusiopathiae is resistant to vancomycin. Thus, rapid differentiation of E. rhusiopathiae from other gram-positive organisms is critical.
The same drugs and doses are appropriate for arthritis (given for at least 1 week after defervescence or cessation of effusion), but repeated needle aspiration drainage of the infected joint is also necessary.
Erysipelothricosis typically results from a penetrating wound in people who handle edible or nonedible animal matter (eg, in a slaughterhouse) or who work with fish or shellfish.
Within 1 week after the injury, a raised, purplish red, nonvesiculated, indurated, maculopapular rash appears, accompanied by itching and burning; about one third of patients have regional lymphadenopathy.
Bacteremia is rare but may result in septic arthritis or infective endocarditis.
Diagnose by culturing a full-thickness biopsy specimen or an exudate obtained by abrading a florid papule.
If endocarditis due to E. rhusiopathiae is suspected, rapid identification of the pathogen is critical because treatment is often different from the usual empiric treatment of gram-positive bacillary endocarditis; E. rhusiopathiae is resistant to vancomycin, which is typically used to treat gram-positive bacillary endocarditis.
Treat with antibiotics (eg, penicillin, ciprofloxacin) based on extent and location of infection.