Skin and Soft Tissue Infections

Skin and soft tissue infections (SSTIs) can be sub-divided based on the anatomical structure(s) affected from superficial to deep. Impetigo affects children more commonly than adults, starting as a macule of erythema and evolving into vesicles that rupture, leaving a golden crusted appearance. Fever and systemic signs are absent. It is highly transmissible and children should be excluded from school until exposed lesions have resolved. Folliculitis is a superficial infection presenting with small papules or pustules on an erythematous base around a hair. Fever and systemic signs are absent. If extension into deeper tissues occurs a dermal abscess (‘boil’ or ‘furuncle’) may occur, and several lesions may coalesce into a ‘carbuncle’. Deeper infection may cause discomfort, fever, and systemic upset. Any hair-bearing area may be affected, but sites most commonly affected include the face, scalp, axilla, inguinal area, thighs, or eyelid (‘stye’), and may be associated with shaved or occluded skin. Cellulitis is rapidly spreading erythema of the skin associated with pain, swelling, fever, and systemic features such as nausea and malaise. It may be seen as a complication of tinea pedis, superficial abrasions, or insect bites, venous insufficiency, lymphoedema, chronic ulcers, and diabetes. It is almost always unilateral and bilateral cellulitis is extremely rare and should prompt consideration of an alternative diagnosis. The Eron grading system can help guide treatment and admission decisions: ● Class I: the patient has no signs of systemic toxicity and no uncontrolled comorbidities. ● Class II: the patient is either systemically unwell or systemically well but with a comorbidity such as peripheral vascular disease, chronic venous insufficiency, diabetes, or obesity, which may complicate or delay resolution of infection. ● Class III: the patient has significant systemic upset such as acute confusion, tachycardia, tachypnoea, hypotension, or unstable comorbidities that may interfere with a response to treatment, or a limb-threatening infection due to vascular compromise. ● Class IV: the patient is septic or has life-threatening infection such as necrotizing fasciitis.