Cellulitis_erysipelas Diagnosis

• Diagnosis is usually made by clinical presentation with or without Gram stain and culture
• On evaluation, location and extent of edema, erythema, warmth, and tenderness are noted so that resolution or progression may be monitored in detail
  
  • Examine for bullae, crepitus, fluctuance, necrosis, purpura, and systemic signs (eg tachycardia, hypotension)

Cellulitis

Uncomplicated

• Area involved is erythematous, warm to the touch, swollen and is distinguished from erysipelas by non-elevated, ill-defined margins
• Primarily involves the subcutaneous tissues and dermis 
• Patients are usually asymptomatic and without comorbidity

Complicated

• Cellulitis in diabetes mellitus (DM) patients including diabetic leg ulcer
• Presence of comorbidities or vascular compromise (eg peripheral vascular disease, chronic venous insufficiency, morbid obesity); if necessary, patients are hospitalized to stabilize comorbid condition
• Presence of significant systemic symptoms: Acute confusion, tachycardia, tachypnea, hypotension
• Signs of potentially severe deep soft-tissue infection: violaceous bullae, cutaneous hemorrhage, skin sloughing, gas in the tissue; surgical debridement of affected area may be required

Purulent

• Presence of purulent exudate or drainage without a drainable abscess

Nonpurulent

• Absence of purulent exudate or drainage and no abscess

Recurrent

• Cellulitis occurring 3-4 times/year even with pharmacological prophylaxis and control of predisposing factors
  
  

Gram Stain, Culture and Sensitivity

• Lesion Culture
  • Cultures of aspirate, biopsy and blood specimens in adults without comorbid conditions yield low results and are generally not indicated
  • Essential only for those with history of malignancy or immunosuppression, recurrent or multiple abscess, treatment failure with initial antibiotic regimen, patients with systemic complications (ie pyrexia, hypotension), predisposing factors (ie immersion injury, animal bites, neutropenia), severe local infection, indication for prophylaxis of infective endocarditis, living in areas with increased S aureus susceptibility patterns
  • Fine-needle aspiration of closed lesions give positive results approximately 30% of the time
  • This technique may be useful when unusual pathogens are suspected (eg immunocompromised patients), when fluctuant areas are detected or when initial antimicrobial therapy failed
  • If a specimen can be taken from the site of origin of the cellulitis, positive culture can be obtained in about ¹/₃ of the patients

• Blood cultures (BC)
  
  • Useful only in patients with significant leukocytosis, severe systemic symptoms, underlying comorbidities, cellulitis complicating lymphedema, buccal or periorbital cellulitis, persistent/recurrent cellulitis, certain exposures (water- related injury or animal bites), and in the elderly or immunocompromised patient
    
    

• Serologic Testing
  
  • Patients with history of recurrent cellulitis may benefit from serologic assays such as anti-streptolysin-O (ASO) reaction, antideoxyribonuclease B test (anti-DNAse B), anti-hyaluronidase test (AHT), or Streptozyme antibody assay
    
    

• Unnecessary in most cases
• Computed tomography (CT) or magnetic resonance imaging (MRI) for suspected necrotizing fasciitis
• Radiographic exams may be used to rule out osteomyelitis and other diseases that may be secondary to underlying comorbidities