Erysipeloid

Erysipeloid is considered to be a zoonotic infection, meaning that exposure to contaminated animal products is a mandatory step in the pathogenesis of the infection [1] [2]. Chicken, turkey, and fish are common animal hosts of Erysipelothrix rhusiopathiae, and its transfer to humans almost exclusively happens after fishing, livestock handling or other occupations involving animal contact [1] [2] [3]. The organism is inoculated onto previously abraded or injured skin (as a result of occupational or accidental injury), and after an incubation period of several days (2-7 in most cases), initial signs and symptoms appear. Because of the nature of acquisition of the infection, lesions predominantly appear on the hands and fingers [4] [5]. Some patients may experience an asymptomatic course of the disease, but burning, itching or throbbing pain at the site of skin injury followed by edema, erythema, and localized inflammation is a typical finding [2] [3]. The lesion is well-defined, contains raised edges and mimics subacute cellulitis, which is why it is often misdiagnosed as erysipelas or cellulitis, caused by streptococcal or staphylococcal species, respectively [3] [5]. Furthermore, the absence of suppuration, together with a history of animal contact and immense pain, are distinguishing features of erysipeloid [3]. In addition, vesicles, bullae, and erosions can be encountered, while proximal lymphadenopathy and signs of more severe infection (fever, arthralgia) are seen in a small number of cases [4] [5]. In the majority of cases, the clinical course is self-limiting, and spontaneous resolution is seen within 3-4 weeks without the need for antibiotic therapy, but in rare cases, relapses have been documented [3] [5].

The diagnosis of erysipeloid may be difficult to obtain without a proper patient history and a thorough examination of the wound. Firstly, a detailed interview with the patient about his/her occupation and possible animal contact, as well as recent injury to the skin is an essential step in order to suspect Erysipelothrix rhusiopathiae as a possible cause. Moreover, a detailed physical examination of the lesion can reveal key features of erysipeloid, and the diagnosis can often be made solely on clinical criteria supported by details from patient history [5]. A confirmation of the pathogen, however, can only be obtained after microbiological testing. A viable sample for cultivation requires a full-thickness biopsy of the lesion (due to the fact that bacteria is located deep within the skin), but the results may be provided after at least 3 or more days [3]. Visualization of thin, gram-positive rods is considered diagnostic, but gram stains and other cultivation methods frequently yield negative results [3]. For this reason, the introduction of novel molecular techniques, such as polymerase chain reaction (PCR), is slowly being introduced into regular practice, since they can rapidly detect bacterial DNA [2].

1. Boyd AS, Ritchie C, Fenton JS. Cutaneous Erysipelothrix rhusiopathiae (erysipeloid) infection in an immunocompromised child. Pediatr Dermatol. 2014;31(2):232-235.
2. Mandell GL, Bennett JE, Dolin R. Mandel, Douglas and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, Pennsylvania: Churchill Livingstone; 2015.
3. Murray PR, Rosenthal KS, Pfaller MA. Medical Microbiology. Seventh edition. Philadelphia: Elsevier/Saunders; 2013.
4. Veraldi S, Girgenti V, Dassoni F, Gianotti R. Erysipeloid: a review. Clin Exp Dermatol. 2009;34(8):859-862.
5. Brooke CJ, Riley TV. Erysipelothrix rhusiopathiae: bacteriology, epidemiology and clinical manifestations of an occupational pathogen. J Med Microbiol. 1999;48(9):789-799.