Skin Abscess

Definitions of Skin/Soft Tissue Infections

  • Cellulitis (see Cellulitis, [[Cellulitis]]): skin infection of deeper dermis and subcutaneous fat (resulting from bacterial breach of the skin) characterized by erythema, warmth, and edema without an underlying suppurative focus
  • Erysipelas (see Erysipelas, [[Erysipelas]]): skin infection of upper dermis and superficial lymphatics (resulting from bacterial breach of the skin) characterized by erythema, warmth, and edema without an underlying suppurative focus
  • Impetigo (see Impetigo, [[Impetigo]]): infection of superficial layers of the epidermis
  • Necrotizing Soft Tissue Infection (see Necrotizing Soft Tissue Infection, [[Necrotizing Soft Tissue Infection]]): all of these are characterized by fulminant tissue destruction, systemic toxicity, and high mortality rates
    • Necrotizing Cellulitis
      • Meleney’s Synergistic Gangrene
      • Clostridial Anaerobic Necrotizing Cellulitis
      • Non-Clostridial Anaerobic Necrotizing Cellulitis
    • Necrotizing Fasciitis: deep-seated infection of subcutaneous tissue (involving fascia and fat), which may spare the skin
      • Type I (Mixed Aerobic and Anaerobic Infection)
      • Type II (Monomicrobial Infection)
    • Necrotizing Myositis (Spontaneous Gangrenous Myositis)
  • Clostridial Myonecrosis (Gas Gangrene) (see Clostridial Myonecrosis, [[Clostridial Myonecrosis]]): life-threatening muscle infection which develops either contiguously from a site of trauma or via hematogenous spread from the gastrointestinal tract to the muscle
  • Furuncle (Boil): infection of hair follicle where purulent material extends through the dermis into the subcutaneous tissue, forming a small abscess
  • Carbuncle: coalescence of several inflamed follicles into a single inflammatory mass with purulent drainage from multiple follicles
  • Skin Abscess: collection of pus within dermis and deeper skin tissues

Predisposing Factors

  • Diabetes Mellitus (see Diabetes Mellitus, [[Diabetes Mellitus]])
  • Immunodeficiency
  • Immunosuppression
  • Intravenous Drug Abuse (IVDA) (see Intravenous Drug Abuse, [[Intravenous Drug Abuse]]): particularly “skin popping”
  • Nasal Carriage of Staphylococcus Aureus (see Staphylococcus Aureus, [[Staphylococcus Aureus]]): may be the only risk factor present in a normal patient who develops skin abscess
  • Skin Barrier Breach


  • General Comments
    • Approximately 7% of Cases are Polymicrobial
  • Staphylococcus Aureus (see Staphylococcus Aureus, [[Staphylococcus Aureus]]: most common etiology
    • Methicillin-Resistant Staphylococcus Aureus (MRSA)
  • Staphylococcus Epidermidis (see Staphylococcus Epidermidis, [[Staphylococcus Epidermidis]]
  • Streptococcus (see Streptococcus, [[Streptococcus]])
  • Nocardiosis (Disseminated) (see Nocardiosis, [[Nocardiosis]]): subcutaneous skin abscesses with/without sinus tracts


Complete Blood Count (CBC) (see Complete Blood Count, [[Complete Blood Count]])

Blood Culture (see Blood Culture, [[Blood Culture]])

  • xxxx


  • Useful to Localize a Defined Pocket of Abscess Fluid
    • Studies Indicate that MRSA Can Be Suspected Based on Ultrasound Characteristics of a Skin Abscess (Acad Emerg Med, 2014) [MEDLINE]

Culture of Abscess Drainage Material

  • Indicated

Clinical Manifestations

Dermatologic Manifestations

Painful/Tender, Erythematous Fluctuant Skin Nodule

  • May have central pustule
  • May be surrounded by a rim of erythematous edema

Other Manifestations

Sepsis (see Sepsis, [[Sepsis]])

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Small Furuncle

  • Warm Compress: when used alone, may promote drainage

Skin Abscess or Medium-Large Furuncle/Carbuncle

  • Incision and Drainage (I+D)
  • Indications for Concomitant Antibiotic Therapy (Based on Infectious Disease Society America/IDSA guidelines)
    • Abscess Present in Difficult to Drain Area: face, hand, genitals
    • Associated Septic Phlebitis
    • Comorbid Disease
    • Extreme of Age
    • Immunosuppression
    • Lack of Clinical Response to Incision and Drainage (I+D) Alone
    • Rapid Progression with Associated Cellulitis
    • Severe or Extensive Disease with Multiple Sites of Infection
    • Systemic Toxicity
  • Clinical Efficacy
    • Trial of Sulfamethoxazole-Trimethoprim for Skin Abscess (NEJM, 2016) MEDLINE]: in skin abscesses at least 2 cm in size which were drained, sulfamethazole-trimethoprim increased cure rate at 7 and 14 days
      • Wound Cultures were Positive for MRSA in 45% of Cases
      • Abscess Size of At Least 2 cm is Considered a Useful Threshold Regarding Deciding on Antibiotic Use as Adjunctive Therapy for Skin Abscess


  • 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 Jul 15;59(2):e10-52. doi: 10.1093/cid/ciu444 [MEDLINE]
  • Management of Skin Abscesses in the Era of Methicillin-Resistant Staphylococcus aureus. N Engl J Med 2014; 370:1039-1047March 13, 2014DOI: 10.1056/NEJMra1212788 [MEDLINE]
  • The Massachusetts abscess rule: a clinical decision rule using ultrasound to identify methicillin-resistant Staphylococcus aureus in skin abscesses. Acad Emerg Med. 2014 May;21(5):558-67. doi: 10.1111/acem.12379 [MEDLINE]
  • Trimethoprim-Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess. N Engl J Med. 2016;374(9):823 [MEDLINE]