CELLULITIS IS AN ACUTE, spreading infection of the dermis or subcutaneous layer of the skin. It may follow damage to the skin, such as a bite or wound. As the cellulitis spreads, fever, erythema, and lymphangitis may occur. Persons with comorbid conditions, such as diabetes, immunodeficiency, or impaired circulation, are at increased risk. If treated promptly, the prognosis is usually good.
Cellulitis of the lower extremity is more likely to develop into thrombophlebitis in an older patient.
- Bacterial infections, commonly with group A streptococcus or Staphylococcus aureus
- Uncommonly, fungal infections
As the offending organism invades the compromised area, it overwhelms the defensive cells (neutrophils, eosinophils, basophils, and mast cells) that normally contain and localize inflammation and cellular debris accumulates. As cellulitis progresses, the organism invades tissue around the initial wound.
SIGNS AND SYMPTOMS
- Classic signs: erythema and edema due to inflammatory response
- Pain at site and possibly in surrounding area
- Fever and warmth
- White blood cell count
- Erythrocyte sedimentation rate
- Gram stain and culture of fluid from abscesses and bulla
- Culture of primary lesion by biopsy or aspiration
- “Touch” preparation—skin lesion specimen touched to microscopic slide; application of KOH; examination for yeast and mycelial forms of fungus
- Oral or IV penicillin (drug of choice for initial treatment) unless patient has known penicillin allergy; antifungal medications if necessary
- Warm soaks to the site to help relieve pain and decrease edema by increasing vasodilation
- Pain medication as needed
- Elevation of infected extremity