ABSCESS

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
Staphylococcus aureus and staphylococcus viridans are common
Escherichia 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
Bacteroides 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
IV drug use
Chron's 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
DIAGNOSIS TESTS & NTERPRETATION
Lab
Routine laboratory tests are not typically indicated.
Glucose determination may be useful if:
Underlying undiagnosed diabetes is a concern
There is a concern for associated 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
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
Elliptical incision prevent early closure
Break loculations with gentle exploration
Irrigate cavity after expressing all pus
Loose packing of abscess cavity when:
Larger than 5 cm
Comorbid medical conditions
HIV
Diabetes
Malignancy
Chronic steroid use
Immunosuppressed
Abscess location: face, neck, scalp, hands/feet, perianal, perirectal, genital
Promote drainage and prevent premature closure
For simple cutaneous abscesses (<5 cm) packing may not be routinely indicated.
Routine antibiotics are not indicated.
Antibiotics are indicated for the following conditions:
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:
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 days 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/Streptococcus 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/Streptococcus 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
Adult dose: 4 mg/kg IV q24h
Linezolid:
Use:
Adult dose: 600 mg IV/PO q12h (peds: 30 mg/kg/d div q8h)
Clindamycin:
Use:
Adult dose: 600 mg (peds: 10–15 mg/kg) IV q8h