Description

• An acute bacterial skin and skin-structure infection (ABSSI) of the dermis and subcutaneous tissue; commonly characterized by pain, erythema, warmth, and swelling:
  • Periorbital cellulitis: Bacterial infection of the eyelid and surrounding tissues
  • Orbital cellulitis: Infection of the eye posterior to the septum; sinusitis is the most common risk factor.
  • Facial cellulitis: Preceded by URI or OM
  • Buccal cellulitis: Infection of cheek in children associated with bacteremia.
  • Peritonsillar cellulitis: Common in children associated with fever, sore throat, and “hot potato” speech.
  • Abdominal wall cellulitis: Common in morbidly obese.
  • Perianal cellulitis: Sharply demarcated, bright, perianal erythema.
  • Necrotizing cellulitis: Gas-producing bacteria in the lower extremities; common in diabetics.
• System(s) affected: Skin/Exocrine

Epidemiology

Predominant sex: Male = Female (perianal cellulitis more common in boys)

Incidence
200 cases per 100,000 patient-years

Prevalence
Unknown

Risk Factors

• Disruption to skin barrier: Trauma, infection, inflammation, edema, and lymphatic obstruction
• Increased risk factor: Elderly, diabetes, hypertension, obesity (1)
• Recurrent cellulitis: Immunocompromised, diabetes, hypertension, cancer, peripheral arterial or venous diseases, chronic kidney disease, dialysis, IV or SC drug use

Genetics
No genetic pattern

General Prevention

• Maintain good skin hygiene.
• Wear support stockings to decrease edema.
• Maintain tight glycemic control and proper foot care for diabetics.

Pathophysiology

Cellulitis is caused by bacterial penetration through a break in the skin. Hyaluronidase mediates SC spread.

Etiology

Microbiology:

• Beta-hemolytic streptococci (groups A, B, C, G, and F), Staphylococcus aureus, including MRSA and gram-negative aerobic bacilli
• Staphylococcus aureus: Periorbital and orbital cellulitis and IV drug users
• Pseudomonas aeruginosa: Diabetics and other immunocompromised patients
• Aeromonas hydrophila and Vibrio vulnificus: Cellulitis caused by waterborne pathogens
• Haemophilus influenzae: Buccal cellulitis
• Clostridia and non–spore-forming anaerobes: Necrotizing cellulitis (crepitant/gangrenous)
• Streptococcus agalactiae: Cellulitis following lymph node dissection
• Pasteurella multocida and Capnocytophaga canimorsus: Cellulitis preceded by bites
• Streptococcus iniae: Immunocompromised hosts
• Rare causes: Mycobacterium, fungal (mucormycosis, aspergillosis, syphilis)