Cellulitis

Also known as: cellulitis, bacterial skin infection, infection of the dermis and subcutaneous tissue, non-purulent cellulitis, erysipelas

Cellulitis is an acute bacterial infection of the deeper layers of the skin and subcutaneous tissue. It usually causes an expanding area of redness, warmth, swelling and tenderness, most often on a lower leg, although any site can be affected. Fever, chills, malaise and swollen lymph nodes may occur. Prompt antibiotic treatment is required because untreated infection can spread and cause serious complications. [S1][S2][S3] Cellulitis usually develops when bacteria enter through a break in the skin, including a cut, ulcer, fissure, insect bite, dermatitis, surgical wound or fungal infection between the toes. Group A Streptococcus and Staphylococcus aureus are common causes, although likely organisms vary with wounds, bites, water exposure, immune status and healthcare exposure. [S3][S4] Diagnosis is usually clinical. A clinician assesses the appearance, rate of spread, systemic symptoms, entry site, comorbidities and possible mimics. Investigations may be needed when disease is severe, recurrent, purulent, atypical, associated with systemic illness or failing to improve. Antibiotics are the core treatment. Route, choice and duration depend on severity, likely organisms, allergy history, comorbidities and local antimicrobial guidance. Elevation, hydration, analgesia and treatment of skin breaks or fungal infection may also be advised. Marking the edge of redness can help monitor spread. [S1][S2][S4] Acupuncture, moxibustion, cupping, gua sha and Chinese herbal medicine must not be used as substitutes for antibiotics or medical assessment. There is no acceptable evidence that they eradicate the bacterial infection. During active cellulitis, local needling, heat, massage, scraping, cupping and topical herbal products over the affected area are contraindicated because they may worsen tissue injury, obscure progression or introduce further infection. [S5]