Ecthyma

Are You Confident of the Diagnosis?

Characteristic findings on physical examination

Ecthyma is an ulcerative infection of the skin, caused by group-A beta-hemolytic streptococci. In its earliest stage, ecthyma may present in a similar fashion to impetigo. Lesions of ecthyma may result from primary infection, or from secondary infection of other lesions or wounds. There are usually less than ten lesions present (Figure 1.)

Ecthyma on dorsal hand of 55-year old-alcoholic who presented to the emergency room (Courtesy of Chad Hivnor, MD)

Ecthyma usually begins as a small vesicle or pustule. Over the period of several days, theses lesions increase in size and form an overlying crust. The ulcer appears shallow and punched-out when the crust is removed. Ecthyma heals slowly, and residual scarring is left. Regional lymphadenopathy is common, while systemic symptoms, cellulitis, and osteomyelitis is very infrequent.

Diagnosis confirmation

Gram stain and culture may be used for micrbiologic confirmation. The differential diagnosis includes ecthyma gangrenosum, insect bites, pyoderma gangenosum, and infections which cause ulcerative lesions. These infections include entities such as sporotrichosis, leishmaniasis, Mycobacterium marinum, and deep fungal infections to differentiate the infections, culture and biopsies would be indicated.

Who is at Risk for Developing this Disease?

Individuals with immunosuppressive conditions are at higher risk for ecthyma, as are those with preexisting dermatoses or wounds. Individuals with areas of skin injury also have a higher risk. Poor hygiene, crowded conditions, and high temperature and humidity are other risk factors. There is no racial or sexual predisposition.

What is the Cause of the Disease?

Etiology

As noted above, streptococci usually initiate the disease. Staphylococci may contaminate these lesions once they form.

Systemic Implications and Complications

Systemic complications, including cellulitis, osteomyelitis, and bacteremia, are very rare.

Treatment Options

Treatment options are summarized in Table I.

Table I.

Topical	Systemic	Surgical
Mupirocin or retapamulin ointment	Oral penicillin/antistaphylococcal antibiotics (cephalexin 250mg po four times a day; penicillin VK 0.25-0.5g po four times a day; Clindamycin 150-300 mg po four times a day	Debride ecthyma crusts
	Intravenous antibiotics with coverage for streptococci/staphylococci (clindamycin 600–1200mg/day in 2, 3 or 4 equal doses; cephalexin 500mg-1g every 12 hours)

Optimal Therapeutic Approach for this Disease

Topical therapy for mupurocin ointment may be considered for localized disease. In terms or oral therapy, ecthyma caused by streptococci can be adequately treated with a 10-day course of an antibiotic with Gram-positive activity, such as cephalexin or dicloxicillin. In the event of secondary stapylococcal involvement, therapy should be based on microbiologic findings. For more widespread involvement, intravenous antibiotics, including such drugss clindamycin, oxacillin, and vancomycin, should be considered.

Patient Management

The prognosis is favorable. As above, lesions heal slowly over several weeks. Avoiding predisposing factors may be warranted to reduce recurrence. The patient should be monitored closely, with follow-up within 1 week after presentation, or sooner if the condition warrants

Unusual Clinical Scenarios to Consider in Patient Management

Patients with a history of immunosuppression or with other comorbidites should be monitored closely. Ecthyma gangrenosum, which is in the differential diagnosis of ecthyma, is associated with a Pseudomonas aeruginosa bacteremia. This entity usually occurs in patients who are critically ill and immunocompromised.

What is the Evidence?

Wasserzug, O, Valinsky, L, Klement, E. “A cluster of ecthyma outbreaks caused by a single clone of invasive and highly infective Streptococcus pyogenes”. Clin Infect Dis. vol. 48. 2009. pp. 1213-9. (This study demonstrates the possible ramifications of the combination of a virulent and highly infective S. pyogenes strain and poor living conditions, and it emphasizes the importance of early intervention in such conditions.)

Martin, JM, Green, M. “Group A streptococcus”. Semin Pediatr Infect Dis. vol. 17. 2006. pp. 140-8. (The article reviews the manifestations of group A streptococci (GAS). Infections due to GAS include pharyngitis, impetigo, ecthyma, erysipelas, and cellulitis. These infections, as well as the manifestations of invasive disease including streptococcal toxic shock syndrome and necrotizing fasciitis, are reviewed in this article.)

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