Cellulitis

“Acute bacterial infection of the dermis and subcutaneous tissue”

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