Critical Alerts

• Incision and drainage (I&D) is primary treatment: Antibiotics alone are insufficient
• MRSA is common pathogen: Consider in purulent infections
• Antibiotics adjunct in select cases: Surrounding cellulitis, systemic illness, immunocompromise
• Rule out necrotizing fasciitis: Disproportionate pain, rapid spread, crepitus
• Packed wounds may need repacking: Follow-up in 24-48 hours
• Recurrent abscesses warrant MRSA decolonization consideration

Necrotizing Fasciitis Warning Signs

Emergency Treatments

Overview

A skin abscess is a localized collection of pus within the dermis and deeper skin tissues. It is most commonly caused by Staphylococcus aureus, including MRSA. Incision and drainage (I&D) is the primary treatment. Antibiotics are adjunctive in select cases. The key ED task is distinguishing simple abscess from complicated infection (cellulitis, necrotizing fasciitis).

Classification

By Size/Depth:

Epidemiology

• Very common: ~3% of ED visits are skin/soft tissue infections
• Rising incidence: Community-acquired MRSA (CA-MRSA)
• Common sites: Buttocks, groin, axilla, extremities

Etiology

Pathogens:

Risk Factors:

Necrotizing Fasciitis

Complicated Abscess

Other Causes of Skin Swelling

Clinical Diagnosis

• Abscess is a clinical diagnosis
• Fluctuance is key finding

Ultrasound

Indications:

• Differentiating abscess from cellulitis
• Locating abscess for I&D
• Assessing size and depth

Findings:

• Hypoechoic fluid collection
• Posterior acoustic enhancement

Laboratory

Discharge Criteria

• Successful I&D
• No systemic illness
• Able to perform wound care or have follow-up for repacking
• Reliable follow-up

Admission Criteria

• Necrotizing fasciitis concern
• Extensive cellulitis
• Sepsis
• Failed outpatient I&D
• Immunocompromised with severe infection
• Facial abscess with concern for spread

Referral

Follow-Up

Condition Explanation

• "You have a skin abscess, which is a pocket of pus under the skin."
• "The best treatment is to drain it, which we did."
• "You may need antibiotics to help prevent the infection from spreading."

Wound Care

• Keep dressing clean and dry
• Return for packing removal/change in 24-48 hours
• Warm compresses may help
• Take antibiotics as directed (if prescribed)

Prevention (MRSA)

• Don't share towels, razors, or personal items
• Keep cuts and scrapes clean and covered
• Wash hands frequently
• Consider bleach baths (1/4 cup bleach to full bathtub) if recurrent

Warning Signs to Return

• Fever
• Increasing redness or swelling
• Pain getting worse
• Red streaks spreading
• Not improving in 48 hours

Diabetes

• Higher infection risk
• Consider antibiotics even for simple abscess
• Close follow-up

Immunocompromised

• Broader antibiotic coverage
• Lower threshold for admission
• Consider atypical pathogens

Injection Drug Users

• Consider endocarditis if bacteremia
• Blood cultures if febrile
• Screen for HIV, hepatitis

Recurrent Abscesses

• Consider MRSA decolonization
• Mupirocin nasal ointment × 5 days
• Bleach baths
• Chlorhexidine washes

Performance Indicators

Documentation Requirements

• Size of abscess
• Amount of purulent drainage
• Presence of cellulitis
• Wound packing
• Antibiotic prescribed (if any)
• Follow-up plan

Diagnostic Pearls

• Fluctuance = Abscess: Needs I&D
• Ultrasound if uncertain: Differentiates abscess from cellulitis
• Pain out of proportion = Necrotizing fasciitis: Emergency
• Recurrent abscesses suggest MRSA colonization
• Perirectal abscess needs surgical evaluation

Treatment Pearls

• I&D is primary treatment: Antibiotics alone don't work
• Pack large cavities: Prevents premature closure
• TMP-SMX or doxycycline for MRSA coverage: If antibiotics needed
• Antibiotics NOT needed for simple, uncomplicated abscess
• Warm compresses promote drainage

Disposition Pearls

• Most can be discharged: After I&D
• Follow-up for packing removal: 24-48 hours
• Admit for nec fasc, sepsis, or extensive infection
• MRSA decolonization for recurrent cases