- Erysipelas and cellulitis are infections of the dermis and subcutaneous layers of the skin that are rapidly progressive and are often accompanied by systemic signs, such as fever, leukocytosis, and elevated markers of systemic inflammation.
- Both erysipelas and cellulitis require systemic antibiotic therapy.
- The clinical presentation of erysipelas and cellulitis are similar, presenting with unilateral erythema, edema, warmth, and tenderness. Systemic signs of inflammation (fever, malaise, leukocytosis) are almost always seen. There are several distinguishing features listed below.
- Erysipelas affects the lower extremities (76% of cases) but commonly has facial involvement (17%), is unilateral, sharply demarcated, typically involves more superficial lymphatics within the dermis to give a waxy or intensely superficial edematous (peaud’orange) appearance.
- Cellulitis commonly affects the lower extremities, typically affects one limb, and may result from an underlying abscess or trauma.
- Trauma, surgery, preexisting skin disease, and chronic lymphedema may be risk factors for cellulitis.
- There is an important non-infectious differential diagnosis of cellulitis, including contact dermatitis, venous stasis dermatitis, deep vein thrombosis, and vasculitis. Venous stasis dermatitis is commonly bilateral, and is not accompanied by signs of systemic inflammation.
- Most cases of cellulitis are caused by streptococci. Staphylococcus aureus is an important consideration in cases of cellulitis associated with trauma or an underlying abscess.
Cellulitis can occur as a primary disease entity or it can complicate a preexisting dermatosis (i.e., microbes may enter the skin via either an inapparent or an obvious portal of entry). It accounts for 10% of infection-related hospitalizations in the United States (US), and is a common presentation for ambulatory visits in the US. The choice of parenteral versus oral therapy is influenced by the presentation of fever, leukocytosis, and/or lymphangitis, and by the location of the infection (e.g., classic erysipelas of the face). Rapidly progressive disease, cellulitis that complicates preexisting edema of the lower extremities, cellulitis with significant neutrophilia, and cellulitis in immunosuppressed, diabetic, and neutropenic patients requires parenteral therapy. Although initial therapy is dictated by the likelihood that the causative organisms are streptococci or, less likely, S. aureus, in immunocompromised individuals many other organisms may be responsible. More serious soft tissue infections, such as early necrotizing fasciitis, may resemble cellulitis. The following situations require alternative management strategies than those outlined below since they may be caused by unusual organisms: buccal cellulitis (Haemophilus influenzae), diabetic foot ulcer associated cellulitis (gram-negative organisms and anaerobes), human bites (oral anaerobes, Eikenella, Streptococcus viridans), dog and cat bites (Pasteurella multocida, Capnocytophaga canimorsus), cellulitis associated with salt water exposure (Vibrio vulnificus), cellulitis associated with exposure to fresh water (Aeromonas), and cellulitis in a butcher (Erysipelothrix).
Erysipelas is a superficial form of cellulitis that involves superficial lymphatics located within the upper dermis. Beta-hemolytic streptococci are the most common cause, followed by group B, C, and G streptococci, and rarely by staphylococci or other bacterial organisms.