Cellulitis

BASICS

BASICS

BASICS

Skin and soft tissue infections (SSTIs) are a common health burden with approximately a quarter of patients requiring hospitalization, leading to >650,000 admissions per year in the United States.

DESCRIPTION

DESCRIPTION

DESCRIPTION

  • Acute bacterial infection of the dermis and subcutaneous tissue
  • Types and locations:
    • Most common on lower extremities, unilateral
    • Periorbital cellulitis: infection of the eyelid and surrounding tissues
    • Orbital cellulitis: infection of the eye posterior to the septum; most common risk factor is sinusitis.
    • Facial cellulitis: preceded by URI or otitis media
    • Buccal cellulitis: infection of cheek in children associated with bacteremia (common before Haemophilus influenzae type B vaccine)
    • Peritonsillar cellulitis: common in children; associated with fever, sore throat, and “hot potato” speech
    • Perianal cellulitis: sharply demarcated, bright, perianal erythema
    • Necrotizing cellulitis: gas-producing bacteria in the lower extremities; more common in diabetics

EPIDEMIOLOGY

EPIDEMIOLOGY

EPIDEMIOLOGY

  • Predominant sex: male = female
  • Increased hospitalizations for cellulitis in the summer and fewer in the winter months

Incidence

Incidence

Incidence

1.5 to 24.6 per 1,000 person-years with recurrence rate ranging from 16% to 53% within 3 years.

Prevalence

Prevalence

Prevalence

Visits to U.S. ambulatory practices for purulent SSTI range from 5.4 to 11.3 million visits annually.

ETIOLOGY AND PATHOPHYSIOLOGY

ETIOLOGY AND PATHOPHYSIOLOGY

ETIOLOGY AND PATHOPHYSIOLOGY

Caused by bacterial penetration through a compromise in the epidermis into the deep dermis and subcutaneous tissues.

  • Microbiology
    • β-Hemolytic streptococci (groups A, B, C, G, and F), staphylococci (Staphylococcus aureus, including MRSA) and gram-negative aerobic bacilli most common
    • S. aureus seen in periorbital and orbital cellulitis and people who inject IV drugs
    • Pseudomonas aeruginosa seen in diabetics and other immunocompromised patients
    • H. influenzae causes buccal cellulitis.
    • Clostridia and non–spore-forming anaerobes: necrotizing cellulitis (crepitant/gangrenous)
    • Streptococcus agalactiae: following lymph node dissection
    • Pasteurella multocida and Capnocytophaga canimorsus: precipitated by bites
    • Streptococcus iniae: immunocompromised hosts
    • Rare causes: Mycobacterium, fungal (mucormycosis, aspergillosis)

Genetics

Genetics

Genetics

None

RISK FACTORS

RISK FACTORS

RISK FACTORS

  • Disruption of skin barrier from trauma, infection, insect bites, injection drug use, body piercing, maceration, ulcerations, chronic wounds, fissured toe webs
  • Inflammation from excoriating skin disorders or radiation therapy
  • Edema due to venous insufficiency; lymphatic obstruction due to surgery or congestive heart failure
  • Advanced age, male gender, diabetes, hypertension (HTN), cancer, obesity
  • Dermatomycosis, tinea pedis, onychomycosis, presence of S. aureus and/or streptococci in toe webs
  • Previous episode of cellulitis
  • Recurrent cellulitis:
    • Cellulitis recurrence score (predicts recurrence of lower extremity cellulitis based on presence of lymphedema, chronic venous insufficiency, peripheral vascular disease, and deep venous thrombosis)
    • Recurrent cellulitis is seen in immunocompromised patients (HIV/AIDS), steroids and TNF-α inhibitor therapy, diabetes, hypertension, cancer, peripheral arterial or venous diseases, chronic kidney disease, dialysis, IV or SC drug use.

GENERAL PREVENTION

GENERAL PREVENTION

GENERAL PREVENTION

  • Good skin hygiene and hydration to avoid dryness and cracking
  • Management of edema with elevation, compression stockings, pneumatic pressure pumps
  • Maintain glycemic control and proper foot care in diabetic patients.

COMMONLY ASSOCIATED CONDITIONS

COMMONLY ASSOCIATED CONDITIONS

COMMONLY ASSOCIATED CONDITIONS

Abscess, lymphedema, venous insufficiency, stasis dermatitis, obesity

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