Cellulitis

Background

Cellulitis of the leg
  • Acute spreading infection of the dermis and subcutanous tissue, causing overlying skin inflammation[1]
  • Most often caused by streptococcus or staphylococcus (including MRSA)
  • Risk factors[2]
    • Previous cellulitis
    • Wound or current leg ulcers
    • Excoriating skin diseases
    • Lymphedema
    • Venous insufficiency
    • Obesity
    • Tinea pedis

Clinical Features

  • Rash
    • Local erythema, warmth, swelling
    • Tender indistinct margins
  • Can be accompanied by fever, chills, malaise, headache, nausea/vomiting

Differential Diagnosis

Skin and Soft Tissue Infection

Look-A-Likes

Hand and finger infections

Foot infection

Look A-Likes

Evaluation

  • Generally clinical diagnosis, may be assisted by ultrasound (above)
  • Ultrasound can aid in diagnosis - may see "cobblestoning" of subcutaneous fat due to accumulation of fluid in these tissues. Also helpful to evaluate for abscess.

Management

Antibiotics

Tailor antibiotics by regional antibiogram[3]

Outpatient

Coverage primarily for Strep

MRSA coverage only necessary if cellulitis associated with: purulence, penetrating trauma, known MRSA colonization, IV drug use, or SIRS[4]

  • 5 day treatment duration, unless symptoms do not improve within that timeframe[4]
    • Cephalexin 500mg PO q6hrs OR
      • Add TMP/SMX DS 1 tab PO BID[5] if MRSA is suspected
      • Most cases of non-purulent cellulitis are caused by Strep. In these cases, the addition of TMP/SMX has been demonstrated to offer no clinical benefit over cephalexin alone.[6]
    • Clindamycin 450mg PO TID covers both Strep and Staph
    • Tetracyclines (like Doxycycline) should be avoided in non-purulent cellulitis due to high rates of Strep resistance[7]

Inpatient

Saltwater related cellulitis

coverage extended for Vibrio vulnificus

Freshwater related cellulitis

coverage extended for Aeromonas sp

Predictors of Treatment Failure[8]

  • Fever (T>38°C) at triage (odds ratio [OR] 4.3)
  • Chronic leg ulcers (OR 2.5)
  • Chronic edema or lymphedema (OR 2.5)
  • Prior cellulitis in the same area (OR 2.1)
  • Cellulitis at a wound site (OR 1.9)

Disposition

  • Admit for:
    • Sepsis
    • Significant hand, face, or genitalia infection
    • Failure of outpatient treatment
    • Significant comorbidity (e.g. immunocompromized, poorly controlled diabetes)

See Also

References

  1. Gunderson CG, Martinello RA. A systematic review of bacteremias in cellulitis and erysipelas. J Infect. 2012 Feb;64(2):148-55.
  2. Quirke M et al. Risk factors for nonpurulent leg cellulitis: a systematic review and meta-analysis. Br J Dermatol. 2017 Aug;177(2):382-394.
  3. Stevens D, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-e52
  4. 4.0 4.1 Stevens D, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-e52
  5. Cadena J, et al. Dose of trimethoprim-sulfamethoxazole to treat skin and skin structure infections caused by methicillin-resistant Staphylococcus aureus. Antimicrobial agents and chemotherapy 55.12 (2011): 5430-5432.
  6. Pallin D, et al. Clinical trial: comparative effectiveness of cephalexin plus trimethoprim-sulfamethoxazole versus cephalexin alone for treatment of uncomplicated cellulitis: a randomized controlled trial. Clinical infectious diseases 56.12 (2013): 1754-1762
  7. Traub, W and Leonhard, B. Comparative susceptibility of clinical group A, B, C, F, and G beta-hemolytic streptococcal isolates to 24 antimicrobial drugs. Chemotherapy 43.1 (1997):10-20.
  8. Peterson D. et al. Predictors of failure of empiric outpatient antibiotic therapy in emergency department patients with uncomplicated cellulitis. Acad Emerg Med. 2014 May;21(5):526-31.