Treatment Guideline Chart
Cellulitis is an acute spreading skin infection that may go deep, involving the subcutaneous tissues.
It typically occurs in areas where the skin integrity has been compromised.
May result from blood-borne spread of infection to the skin and subcutaneous tissues.
It is commonly caused by beta-hemolytic streptococci and Staphylococcus aureus in adults and Haemophilus influenzae type B in patients <3 year of age.

Cellulitis_erysipelas%20(pediatric) Diagnosis


  • Diagnosis is usually made by clinical presentation with or without Gram stain and culture
  • Clinical response is usually evident within 24-48 hours
  • Disease progression despite receipt of oral antibiotics suggests infection with resistant microbes, an underlying condition or presence of a deeper, more serious infection
  • In patients who become increasingly ill or experience increasing toxicity, an aggressive evaluation should be initiated, and antibiotic treatment modified on the basis of Gram stain results, culture results and antimicrobial susceptibilities of organisms obtained from surgical specimens


Uncomplicated Cellulitis

  • 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
  • Erysipelas is more common among infants and young children
  • Local tenderness and regional adenopathy are usually present
  • Constitutional signs and symptoms are usually present (eg fever, chills and malaise)

Complicated Cellulitis

  • Cellulitis in patients with diabetes mellitus (DM)
  • Facial cellulitis, as meningitis may occur
  • Presence of comorbidities (eg peripheral vascular disease, chronic venous insufficiency, morbid obesity)
  • Presence of significant systemic symptoms (eg irritability, tachycardia, tachypnea, hypotension)
  • Signs of potentially severe deep soft-tissue infection (eg violaceous bullae, cutaneous hemorrhage, skin sloughing, gas in the tissue)

Purulent Cellulitis

  • Presence of purulent exudate or drainage without a drainable abscess

Nonpurulent Cellulitis

  • Absence of purulent exudate or drainage and no abscess

Recurrent Cellulitis

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

Laboratory Tests

Gram Stain, Culture and Sensitivity

  • Cellulitis in a neonate should prompt a full sepsis evaluation
  • Etiology of cellulitis remains unidentified in most patients and empiric treatment may be based on clinical presentation
  • Lesion culture
    • Cultures of aspirate, biopsy and swabs identify causative organism in ~25% of cases
    • If a specimen can be taken from the site of origin of the cellulitis, positive culture can be obtained in about 1/3 of patients
    • Essential only for those with history of malignancy, systemic complications (eg pyrexia, hypotension), predisposing factors (eg immersion injury, animal bites, neutropenia)
  • Blood cultures (BC)
    • Useful only in patients with significant leukocytosis, neutropenia, acute onset and high fever, animal bites, immersion injuries, in immunocompromised or in a toxic-appearing patient 
  • Lumbar puncture should be done if H influenzae facial cellulitis is suspected, or if there are signs of systemic toxicity
  • 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) scan for suspected necrotizing fasciitis
  • Radiographic exams may be used to rule out osteomyelitis

Differential Diagnosis

  • Necrotizing fasciitis
  • Toxic shock syndrome
  • Erythema migrans
  • Gas gangrene
  • Contact dermatitis
  • Herpes zoster
  • Drug reaction, vaccination site reaction
  • Deep venous thrombosis
  • Vasculitis
  • Lymphedema
  • Lipodermatosclerosis
  • Insect bite
  • Rheumatologic diseases: Septic arthritis, septic bursitis, osteomyelitis, acute gout
Editor's Recommendations
Special Reports