Cellulitis

Aka: Cellulitis, Staphylococcal Cellulitis, Streptococcal Cellulitis

1. See Also
   1. Skin Infection
   2. Hand Infection
   3. Nodular Lymphangitis
   4. Erysipelas
   5. Impetigo
   6. Preseptal Cellulitis and Periorbital Cellulitis
   7. Cellulitis in Diabetes Mellitus
2. Risk factors
   1. Also see Group A Streptococcus Cellulitis (Erysipelas)
   2. Trauma
      1. Laceration
      2. Puncture Wound
      3. Post-operative infection at incision site
   3. Underlying skin lesion
      1. Superficial Folliculitis or Furuncle (Staphylococcus infection)
      2. Skin Ulcer
      3. Fungal Dermatoses
      4. Non-Group A Streptococcus Cellulitis related lesions
         1. Coronary Artery bypass with saphenous vein graft
         2. Radical pelvic surgery or radiation
   4. Neoplasms
      1. Lymphatic Cutaneous metastases from neoplasms
      2. Inflammatory Breast Cancer
      3. Carcinoma Erysipeloides
   5. Extremity Stasis or Edema
      1. Chronic Dependent edema (may progress rapidly)
      2. Peripheral Vascular Disease
   6. Perianal Streptococcal Cellulitis (in children)
   7. Diabetes Mellitus
      1. See Cellulitis in Diabetes Mellitus
   8. Immunocompromised patients
3. Causes: General
   1. Common (most Cellulitis cases)
      1. Staphylococcal Cellulitis
      2. Group A Streptococcus Cellulitis (Erysipelas)
   2. Less common Streptococcal infections
      1. Pneumococcus
      2. Non-Group A Streptococcus Cellulitis
         1. Group C or G Streptococcus Cellulitis
         2. Group B Streptococcus Cellulitis in newborns
   3. Rapidly progressive Cellulitis
      1. See Necrotizing Fasciitis
      2. Vibrio Cellulitis (Vibrio vulnificus)
      3. Clostridium perfringens
      4. Pasteurella multocida
      5. Aeromonas Hydrophila
4. Causes: Exposure
   1. Fish Handlers or water exposure (See Marine Trauma)
      1. Erysipelothrix rhusiopathiae (Erysipeloid)
      2. Mycobacterium marinum (Fish tank exposure)
      3. Aeromonas Hydrophila
      4. Vibrio Cellulitis
   2. Animal Bites
      1. Cat Bites
         1. Pasteurella multocida
      2. Dog Bites
         1. Staphylococcus intermedius
      3. Envenomation spines of stonefish (South Pacific)
         1. Risk of serious systemic toxicity, pulmonary edema
      4. Human Bites
         1. See Fight Bite
   3. Miscellaneous
      1. Pseudomonas aeruginosa
         1. Sweaty Tennis Shoe Syndrome
      2. Eosinophilic Cellulitis
5. Immunocompromised Patients
   1. Serratia
   2. Proteus
   3. Enterobacteriaceae
   4. Cryptococcus
   5. Legionella pneumophila
      1. Associated with Legionella pneumonia
   6. Legionella micdadei
      1. Seen in renal transplant patients
   7. Escherichia coli
      1. Seen in children with relapsing Nephrotic Syndrome
6. Symptoms
   1. Inflamed skin wound develops rapidly days after injury
      1. Local tenderness
      2. Pain
      3. Very red, hot, swollen an painful
   2. Associated symptoms
      1. Malaise
      2. Fever, chills
7. Signs
   1. Draw margins of erythema with marker
      1. Follow course of infection on antibiotics
   2. Wound with contiguous inflammation
      1. Erythema (Rubor)
      2. Swelling (Tumor)
      3. Local tenderness (Dolor)
      4. Warm to touch (Calor)
   3. Abscess
      1. Hallmark of Staphylococcus aureus
   4. Regional spread
      1. Ascending lymphangitis
      2. Regional Lymphadenopathy
   5. Small patches of necrosis
   6. Gram Negative superinfection may also be present
   7. Hemorrhagic and necrotic bullae (specific conditions)
      1. Group A Streptococcal Cellulitis
      2. Pseudomonas Cellulitis
      3. Vibrio Cellulitis (Vibrio vulnificus)
      4. Clostridium perfringens
      5. Aeromonas Hydrophila
8. Differential Diagnosis: Non-infectious Conditions
   1. Vascular Conditions
      1. Superficial Thrombophlebitis
      2. Deep Vein Thrombosis
   2. Dermatologic Conditions
      1. Contact Dermatitis
      2. Insect Bites
      3. Acute Drug Reaction
      4. Eosinophilic Cellulitis
      5. Sweet Syndrome
   3. Rheumatologic Conditions
      1. Gouty Arthritis
      2. Relapsing Polychondritis
   4. Miscellaneous
      1. Erythromelalgia
      2. Inflammatory Carcinoma (metastatic cancer to skin)
      3. Foreign body reaction (mesh, metal, silicone implant)
      4. Familial Mediterranean fever
   5. References
      1. Vergidis (2005) Ann Intern Med 142:47-55
9. Labs
   1. Blood Culture (25% sensitivity)
   2. Skin biopsy (25% sensitivity)
   3. Fine Needle Aspiration
   4. Saline injection and aspiration
      1. Listed for historical purposes only (rarely done in clinical practice)
      2. Technique
         1. Leading edge injection and aspiration with saline
      3. Efficacy
         1. May assist diagnosis with Cellulitis
         2. Not useful in Erysipelas
         3. 30% sensitivity from closed lesions (efficacy may be as low as 5%)
      4. Indication
         1. Unusual pathogens suspected
         2. Cellulitis refractory to current antibiotics
10. Imaging
    1. Soft tissue Ultrasound
       1. Abcess formation is consistent with staphylococcal infection
11. Management: General Care
    1. Tetanus prophylaxis
    2. Immobilization and elevation of involved limb
       1. Splint in a position of function
       2. Decreases swelling
    3. Clean wound site
       1. Copious irrigation
       2. Debride devitalized tissue
       3. Incision and Drainage if deep fluctuant pocket
    4. Compresses
       1. Cool sterile saline dressings decrease pain
       2. Later, moist heat helps localize infection
12. Management: Factors affecting antibiotic selection and course
    1. Distinguish Erysipelas, abscess and Cellulitis
       1. Erysipelas (superficial)
          1. Sharply demarcated, bright red, indurated
          2. Typically caused by Group A Streptococcus
       2. Cellulitis (deep, subcutaneous)
          1. Abrupt onset of indistinct faint erythema with rapidly advancing border
          2. Typically caused by group A. Streptococcus or Group G (although Staphylococcus can cause this as well)
       3. Abscess
          1. Hallmark of Staphylococcus aureus infection
          2. Primary management is Incision and Drainage
          3. If antibiotics are needed (Cellulitis with abscess), then cover MRSA (see below)
       4. Other bacterial Skin Infections
          1. Folliculitis
          2. Impetigo
    2. Distinguish most likely organism: Streptococcus or Staphylococcus
       1. Streptococcus (especially Group A Streptococcus)
          1. Streptococcus (especially Group A) is the most common cause of Cellulitis and Erysipelas
          2. Abrupt onset with rapid spread
          3. May be associated with fever and ascending lymphangitis
          4. Typically associated with an inciting skin injury with associated break in the skin (e.g. Tinea Pedis)
       2. Staphylococcus (typically MRSA)
          1. Less common cause of Cellulitis
          2. Typically presents without a primary skin injury site
          3. Primary source is often a Folliculitis
          4. Abscess is often present (Incision and Drainage is primary treatment)
             1. Consider soft tissue Ultrasound if suspect occult abscess
    3. Consider Antibiotic Resistance
       1. Avoid Fluoroquinolones in Cellulitis due to high resistance
       2. Staphylococcus aureus infections are often due to MRSA
    4. Course
       1. Standard course has been 10 days of antibiotics
       2. New: 5 day as effective as 10 day if uncomplicated
       3. Hepburn (2004) Arch Intern Med 164:1669-74
13. Management: Extremity Infections (non-diabetic patients)
    1. See Skin Infections in Diabetes Mellitus
    2. Erysipelas (well demarcated and bright red): Streptococcus coverage
       1. Treat as Cellulitis with broader coverage unless classic Erysipelas appearance
       2. Mild-Moderate infections (oral, oupatient management)
          1. Penicillin VK 500 mg orally four times per day for 7-10 days or
          2. Amoxicillin 500 mg orally three times per day for 7-10 days or
          3. Cephalexin 500 mg orally four times per day for 7-10 days
       3. Penicillin Allergy
          1. Azithromycin 500 mg orally on day 1, then 250 mg orally on days 2-5
          2. Clindamycin 300 mg orally four times per day for 7-10 days
       4. Severe infections (requiring IV antibiotics)
          1. Penicillin G 2 million units IV every 6 hours or
          2. Cefazolin 1 gram IV every 8 hours or
          3. Clindamycin 600 mg IV every 8 hours or
          4. Vancomycin 15 mg/kg IV every 12 hours
    3. Cellulitis (less distinct margins): Streptococcus and Staphylococcus coverage
       1. First Line: Streptococcus (most likely) and MSSA coverage
          1. Oral
             1. Cephalexin 500 mg orally four times per day for 7-10 days or
             2. Dicloxacillin 500 mg orally four times per day for 7-10 days or
             3. Amoxicillin-Clavulanate (Augmentin) 875 mg orally twice per day for 7-10 days
          2. Parenteral (more severe infections)
             1. Cefazolin 1 gram IV every 8 hours or
             2. Nafcillin 2 grams IV q4 hours or
             3. Oxacillin 2 grams IV q4 hours
          3. Outpatient parenteral (adults, narrower spectrum parenteral protocol)
             1. Protocol: Both medications for 7-10 days
                1. Cefazolin 2 gram IV q24 hours AND
                2. Probenacid 1 gram PO q24 hours (Decreases Cefazolin excretion)
             2. References
                1. Grayson (2002) Clin Infect Dis 34:1440-8
       2. Second Line: Streptococcus and MRSA coverage
          1. Oral
             1. Septra DS 2-3 tabs twice daily WITH Penicillin, Amoxicillin, or Cephalexin (see dosing above) or
             2. Clindamycin 300 mg orally four times per day for 7-10 days or
             3. Linezolid 600 mg PO bid (very expensive)
          2. Parenteral (more severe infections)
             1. Vancomycin 15 mg/kg IV every 12 hours or
             2. Linezolid 600 mg IV q12 hours (very expensive) or
             3. Clindamycin 600 mg IV q8 hours
    4. Cellulitis with Abscess (or per Gram Stain): Staphylococcus coverage
       1. Incision and Drainage is primary treatment of abscess
          1. Antibiotics are not required if no Cellulitis is present
          2. Antibiotics are at the discretion of the provider and may be warranted despite lack of Cellulitis
             1. Serious comorbidity
             2. Unreliable follow-up
             3. Large abscess (e.g. 5 cm and greater)
          3. Antibiotic selection and course
             1. Antibiotic selection is the same as for abscess with Cellulitis (typically MRSA)
             2. Choose a single agent (esp. Septra)
             3. Course is brief (3-5 days)
       2. Staphylococcus Cellulitis present: MRSA coverage
          1. Septra DS 2-3 tabs twice daily or
          2. Clindamycin 300 mg orally four times per day for 7-10 days or
          3. Minocycline of Doxycycline 100 mg twice daily for 7-10 days or
          4. Linezolid 600 mg PO bid (very expensive)
       3. Severe infections
          1. Vancomycin 15 mg/kg IV every 12 hours
          2. Linezolid 600 mg IV q12 hours (very expensive)
14. Management: Facial erysipelas
    1. Staphylococcus aureus may be difficult to exclude (despite most cases being Group A Streptococcus)
       1. Guidelines in 2012 recommend covering for MRSA
       2. Sanford guide recommends Vancomycin parenterally or Linezolid orally or IV
    2. Mild to moderate infections
       1. Clindamycin 300 mg orally four times per day or
       2. Augmentin high dose with Septra DS 2 tabs twice daily or
    3. Severe infections
       1. Vancomycin 15 mg/kg IV every 12 hours or
       2. Linezolid 600 mg IV q12 hours (very expensive)
15. Management: Cellulitis in comorbid Diabetes Mellitus
    1. See Skin Infections in Diabetes Mellitus
16. Prevention: Recurrent abscess
    1. Wash all sheets, towels and clothes after an episode
    2. Dispose of used razors
    3. Consider Antibacterial soap (e.g. Chlorhexidine)
    4. Consider Mupirocin (Bactroban) in nares twice daily for 5 days (decolonization)
17. Prevention: Recurrent Cellulitis
    1. Reduce peripheral edema (support stockings)
    2. Good skin hygiene
    3. Prophylactic antibiotics:
       1. Efficacy
          1. Not useful if underlying predisposing condition
       2. No Penicillin Allergy
          1. Penicillin G 1.2 MU IM q4 weeks
          2. Penicillin V 250 mg PO bid
       3. Penicillin Allergic
          1. Erythromycin 500 mg PO qd
          2. Azithromycin 250 mg PO qd
          3. Clarithromycin 500 mg PO qd
18. Complications:
    1. Thrombophlebitis in older patients
    2. Necrotizing Fasciitis
19. References
    1. Gilbert (2011) Sanford Guide
    2. Moran in Majoewsky (2013) EM:Rap 13(2): 11
    3. Stulberg (2002) Am Fam Physician 66(1):119-24