“Acute bacterial infection of the dermis and subcutaneous tissue”
- Skin trauma
- IV drug use (unusual organism)
- Chronic lymphoedemats
- Flora colonising skin e.g commonly Strep. pyogenes and Staph. aureus gain entry e.g. through breaks in skin, burns, insect bites, surgical incisions and IV catheters.
- S. aureus cellulitis spreads from a central localised infection e.g. splinter
- S. pyogenes cellulitis spreads rapidly and diffusely, associated with lymphangitis and fever.
- Recurrent streptococcal cellulitis can be seen in the lower extremities in conjunction with chronic venous stasis or saphenous vein harvest for CABG
- Disruption in cutaneous barrier -> invasion of micro-organisms to the dermal and subcutaneous tissue
- Pain, heat, swelling and erythema, most commonly on the lower limb. Lacks demarcation from uninvolved skin. Formation of blisters and bullae. Fever, malaise, nausea and rigors may accompany the skin changes
- Blood culture, swab for culture if open wound, and sensitivity tests, especially in cases with unusual organisms.
- Diagnosis mainly based on the clinical setting and morphological features of the lesion
- Eron classification used for management decisions (Class I->IV)
- Class I: no signs of systemic toxicity or uncontrolled comorbidities
- Management of uncomplicated cellulitis (Class I): appropriate antibiotic prescription, analgesia, adequate fluid, elevation of affected area to reduce oedema if applicable, advice on when to seek immediate medical review. Management of underlying risk factors
- Hospital admission may be required for class II cellulitis and is necessary for class III-IV cellulitis
- Class II: systemically unwell or systemically well with comorbidity e.g. peripheral arterial disease
- Class III: significant systemic upset, unstable comorbidities which may interfere with treatment, or a limb-threatening infection due to vascular compromise
- Class IV: sepsis or severe life-threatening infection e.g. necrotising fasciitis
- Necrotising fasciitis
- Persistent leg ulceration
- Recurrent cellulitis