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)

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

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

• 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

• 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

• 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

Pre Hospital

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

Initial Stabilization/Therapy

• 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

Medication

• 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

Disposition

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

Follow-Up Recommendations

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

See Also

• Bartholin Abscess
• Bite, Animal
• Cellulitis
• CA-MRSA
• Hand Infection
• Mastitis
• Paronychia