Abscess, Skin/soft Tissue

Basics

Description

  • A localized collection of pus surrounded and walled off by inflamed tissue
    • Abscesses can occur on any part of the body
  • Furuncle:
    • Arises from infected hair follicle
    • Most common on back, axilla, and lower extremities
  • Carbuncle:
    • Larger and more extensive than furuncle
  • Dog/cat bite:
    • Usually polymicrobial
  • Breast:
    • Puerperal:
      • Usually during lactation
      • Located in peripheral wedge
      • Usually staphylococci
    • Duct ectasia:
      • Caused by ecstatic ducts
      • Periareolar location
      • Usually polymicrobial
  • Hidradenitis suppurativa:
    • Chronic abscess of apocrine sweat glands
    • Groin and scalp
    • S. aureus and S. viridans are common
    • E. coli and Proteus may be present in chronic disease
  • Pilonidal abscess:
    • Epithelial disruption of gluteal fold over coccyx
    • Staphylococcal species are most common
    • May be polymicrobial
  • Bartholin abscess:
    • Obstruction of Bartholin duct
  • Perirectal abscess:
    • Originates in anal crypts and extends through ischiorectal space
    • Inflammatory bowel disease and diabetes are predisposing factors
    • B. fragilis and E. coli are most common
    • Requires operative drainage
  • Muscle (pyomyositis):
    • Typically in the tropics
    • S. aureus is most common
  • IV drug abuse:
    • Staphylococcal species are most common
    • MRSA is common
    • May be sterile
  • Paronychia:
    • Infection around nail fold
    • Usually S. aureus
  • Felon:
    • Closed space abscess in distal pulp of finger
    • Usually S. aureus

Etiology

  • Abscess formation typically occurs due to a break in the skin, obstruction of sebaceous or sweats glands, or inflammation of hair follicles. The collection may be classified as bacterial or sterile:
    • Bacterial: Most abscesses are bacterial with the microbiology reflective of the microflora of the involved body part:
      • S. aureus is the most common causative organism
      • Community-acquired MRSA (CA-MRSA) common
  • Sterile: More associated with IV drug abuse and injection of chemical irritants
  • Risk factors for abscess formation:
    • Immunosuppression
    • Soft tissue trauma
    • Mammalian/human bites
    • Tissue ischemia
    • IVDU
    • Crohn disease (perirectal)

Diagnosis

Signs and Symptoms

  • Local:
    • Erythema
    • Tenderness
    • Heat
    • Swelling
    • Fluctuance
    • May have surrounding cellulitis
    • Regional lymphadenopathy and lymphangitis may occur
  • Systemic:
    • Often absent
    • Patients with extensive soft tissue involvement, necrotizing fasciitis, or underlying bacteremia may present with signs of sepsis including:
      • Fever
      • Rigors
      • Hypotension
      • Altered mentation

History
  • Previous episodes: Raise concern for CA-MRSA
  • Immunosuppression
  • Medications:
    • Chronic steroids, chemotherapy
  • IVDU
  • History of mammalian bite

Physical Exam
  • Location and extent of infection
  • Presence of:
    • Associated cellulitis
    • Subcutaneous air
    • Deep structure involvement
  • Involvement of specialty area:
    • Perirectal
    • Hand
    • Face/neck

Essential Workup

  • History and physical exam
  • Gram stain unnecessary for simple abscesses in healthy patients
  • Wound cultures:
    • Not indicated in simple abscesses
    • May help guide therapy if systemic treatment is planned
    • May be useful in confirming CA-MRSA in patients with recurrent abscesses
    • May guide specific therapy in a compromised host, abscesses of the central face or hand, and treatment failures

Diagnostic Tests and Interpretation

Lab
  • Routine lab tests are not typically indicated.
  • Glucose determination may be useful if:
    • Underlying undiagnosed diabetes is a concern
    • There is a concern for associated diabetic ketoacidosis (DKA)
  • For febrile patients who appear septic, systemically ill, or have recent IVDU the following labs are indicated:
    • Blood cultures
    • Lactate
    • Renal function
    • CK if myositis suspected

Imaging
  • Bedside US can be helpful in distinguishing cellulitis from abscess especially in equivocal cases
  • CT/MRI can be helpful in determining deep tissue involvement
  • Plain films may reveal gas in tissue planes

Differential Diagnosis

  • Cellulitis
  • Necrotizing fasciitis
  • Aneurysm (especially with IV drug abusers)
  • Cysts
  • Hematoma

Treatment

Pre Hospital

Caution: Septic patients may require rapid transport with IV access and volume resuscitation

Initial Stabilization/Therapy

Septic patient:
  • Immediate IV access
  • Oxygen
  • Crystalloid volume resuscitation
  • Blood cultures/lactate
  • Early antibiotic therapy—broad spectrum to include MRSA coverage.
  • Rapid source control (abscess drainage)
  • If patient remains hypotensive after volume resuscitation consider:
    • Central venous pressure monitoring
    • Mixed venous sampling

Ed Treatment/Procedures

  • Incision and drainage are the mainstays of treatment
    • Incision should be deep enough to allow adequate drainage
    • The incision should also be wide enough to prevent early skin closure
    • Elliptical incision prevents early closure
    • Break loculations with gentle exploration
    • Irrigate cavity after expressing all pus:
      • Irrigation is still recommended but probably not practiced widely
  • Packing is controversial and small studies cast doubt on efficacy especially for small abscesses (<5 cm)
    • Packing is indicated for the following:
      • Larger than 5 cm
      • Comorbid medical conditions:
        • HIV
        • Diabetes
        • Malignancy
        • Chronic steroid use
        • Immunosuppressed
        • Abscess location: Face, neck, scalp, hands/feet, perianal, perirectal, genital
  • Antibiotics:
    • A recent study demonstrated some value to short- and medium-term cure rates for patients with small (<5 cm) S. aureus abscesses
    • The decision to routinely treat these with antibiotics must include cost of treatment and potential side effects of antibiotics
    • Shared decision making with the patient is recommended
  • Generally accepted indications for antibiotics include:
    • Sepsis/systemic illness
    • Facial abscesses drained into the cavernous sinus
    • Concurrent cellulitis (see Medication)
    • Mammalian bites
    • Immunocompromised hosts
  • Perirectal abscess requires treatment in the operating room
  • Hand infections that may require surgical intervention:
    • Deep abscesses
    • Fight bite abscesses
    • Associated tenosynovitis/deep fascial plane infection
  • Loop drainage technique remains an option with support from small studies:
    • Less invasive
    • Simplifies wound care
    • Procedure:
      • Anesthetize locally
      • Incision made at outer margin of abscess
      • Use a hemostat to break loculations and manually express pus
      • Use hemostat to localize distal margin of abscess and use as guide for a second incision
      • Grasp silicone vessel loop with hemostat and pull through and then gently tie
      • Patient should move loop daily to promote drainage
      • No repeat ED visits generally required
      • Removal in 7–10 d is painless

Pediatric Considerations
Incision and drainage are painful procedures that often require procedural sedation and analgesia

Medication


ALERT
  • Know your local susceptibility patterns
  • Oral antibiotics (moderate associated cellulitis):
    • Amoxicillin/clavulanate:
      • Use: Mammalian bites/MSSA/Strep species
      • Adult dose: 500–875 mg (peds: 40–80 mg/kg/d div q12h) PO q12h
    • TMP-SMX:
      • Use: MRSA
      • Adult dose: 160/800 mg (peds: 4–5 mg/kg) PO BID
    • Clindamycin:
      • Use: MRSA
      • Adult dose: 300–450 mg (peds: 4–8 mg/kg) PO q6h
    • Doxycycline:
      • Use: MRSA
      • Adult dose: 100 mg (peds: over 8 yr: 1.1 mg/kg) PO q12h
    • Cephalexin:
      • Use: MSSA/Strep species
      • Adult dose: 250 mg PO q6h or 500 mg PO q12h (peds: 25–50 mg/kg/d div q12h)
    • Erythromycin:
      • Use: MSSA/Strep species
      • Adult dose: 250–500 mg (peds: 10 mg/kg) PO q6–8h
  • IV antibiotics (systemic illness or extensive associated cellulitis):
    • Ampicillin/sulbactam
      • Uses: Human/mammalian bites and facial cellulitis
      • Adult dose: 1.5–3 g (peds: <40 kg, 75 mg/kg; ≥40 kg, adult dose) IV q6h (max = 12 g/d)
    • Vancomycin:
      • Use: MRSA
      • Adult dose: 15 mg/kg IV q12h (peds: 10–15 mg/kg/d div q6–8 h) (max = 2,000 mg/d)
    • Daptomycin:
      • Use MRSA
      • Adult dose: 4 mg/kg IV q24h
    • Linezolid:
      • Use: MRSA
      • Adult dose: 600 mg IV/PO q12h (peds: 30 mg/kg/d div q8h)
    • Clindamycin:
      • Use: MRSA
      • Adult dose: 600 mg (peds: 10–15 mg/kg) IV q8h

Ongoing Care

Disposition

In accordance with abscess type and severity of infection

Admission Criteria
  • Sepsis/systemic illness
  • Immunocompromised host with moderate/large cellulitis
  • Perirectal involvement
  • Any abscess requiring incision and debridement in the operating room

Discharge Criteria
Most patients with uncomplicated abscesses can be treated with incision and drainage and close follow-up

Follow-Up Recommendations

  • Recheck in 24–48 hr for packing removal and wound check
  • Warm soaks for 2–3 d after packing removal

Pearls and Pitfalls

  • Consider CA-MRSA in recurrent abscesses
  • Pain control is essential during incision and drainage of abscesses
  • Beware of tenosynovitis and deep fascial space infections

Additional Reading

  • Daum RS, Kumar N, Chambers HF. A trial of antibiotics for smaller skin abscesses. N Engl J Med. 2017;377:e36.
  • Hankin A, Everett W. Are antibiotics necessary after incision and drainage of a cutaneous abscess? Ann Emerg Med. 2007;50:49–51.
  • Kessler DO, Krantz A, Mojica M. Randomized trial comparing wound packing to no wound packing following incision and drainage of superficial skin abscesses in the pediatric emergency department. Pediatric Emerg Care. 2012;28:514–517.
  • Ladd AP, Levy MS, Quilty J. Minimally invasive technique in treatment of complex, subcutaneous abscesses in children. J Pediatr Surg. 2012;45:1562–1566.
  • O'Malley GF, Dominici P, Giraldo P, et al. Routine packing of simple cutaneous abscesses is painful and probably unnecessary. Acad Emerg Med. 2009;16:470–473.
  • Talan, DA, Moran GJ, Krishnadasa A, et al. Subgroup analysis of antibiotic treatment for skin abscesses. Ann Emerg Med. 2018;71:21–30.
  • Tsoraides SS, Pearl RH, Stanfill AB, et al. Incision and loop drainage: A minimally invasive technique for subcutaneous abscess management in children. J Pediatr Surg. 2012;45:606–609.

See Also

Authors

Neal P. O'Connor


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