What is the recommended treatment for an otherwise healthy adult patient with a skin abscess, considering potential causative organisms and local resistance patterns?

Treatment of Skin Abscess in Otherwise Healthy Adults

Incision and drainage (I&D) is the primary and often sufficient treatment for uncomplicated skin abscesses in healthy adults, with antibiotics reserved for specific high-risk features. 1, 2

Primary Treatment: Incision and Drainage

• I&D is the cornerstone of therapy and is recommended as definitive treatment for all abscesses, carbuncles, and large furuncles. 1
• For very small furuncles, moist heat application may promote spontaneous drainage and could be sufficient without surgical intervention. 1
• Post-procedure care is straightforward: simply covering the surgical site with a dry dressing is usually adequate. 2
• Needle aspiration, even with ultrasound guidance, is insufficient therapy and should be avoided—it has only 26% success compared to 80% with I&D. 3

When to Add Antibiotics After I&D

The decision to add antibiotics should be based on specific clinical criteria, not routine practice. 1

Indications for Antibiotic Therapy:

• Presence of SIRS criteria: temperature >38°C or <36°C, tachypnea >24 breaths/minute, tachycardia >90 beats/minute, or WBC >12,000 or <4,000 cells/µL 1, 2
• Significant surrounding cellulitis extending beyond the abscess borders 2
• High-risk anatomic locations: face, hands, or genitalia 2, 4
• Markedly impaired host defenses or immunocompromised state 1, 2
• Incomplete source control after drainage 2

Evidence Supporting Selective Antibiotic Use:

While I&D alone achieves cure rates of 69-86%, adding antibiotics improves outcomes to 81-93% cure rates. 5, 6 However, this benefit must be weighed against antibiotic resistance concerns and side effects. 7 The treatment effect is greatest in patients with MRSA infection, fever, or history of MRSA. 8

Antibiotic Selection When Indicated

In areas with prevalent community-acquired MRSA (which accounts for approximately 49% of skin abscess isolates), empiric MRSA-active antibiotics are recommended. 5, 6

First-Line MRSA-Active Options:

• Trimethoprim-sulfamethoxazole (TMP-SMX): 320/1,600 mg twice daily for 7-10 days 2, 6

  • Demonstrated 7.2 percentage point improvement in cure rates over placebo 6
  • Lower recurrence rates at new sites (3.1% vs 10.3%) 6
  • Fewer household member infections (1.7% vs 4.1%) 6

• Clindamycin: Standard dosing for 7-10 days 2, 5

  • Similar efficacy to TMP-SMX (83.1% vs 81.7% cure rates) 5
  • Lower new infection rates at 1 month (6.8% vs 13.5% with TMP-SMX) 5
  • Higher adverse event rate (21.9% vs 11.1% with TMP-SMX), though all resolve without sequelae 5

• Doxycycline or minocycline: Alternative MRSA-active agents (avoid in children <8 years) 2

For Non-MRSA Infections:

• Beta-lactams (penicillinase-resistant penicillins or first-generation cephalosporins) when streptococci are suspected 2
• Dicloxacillin: 125-250 mg every 6 hours for mild to moderate infections, taken on empty stomach at least 1 hour before or 2 hours after meals 9

Treatment Duration

• 5-10 days of antibiotic therapy when indicated 1, 2
• Continue for at least 48 hours after patient becomes afebrile and asymptomatic 9

Special Considerations for Recurrent Abscesses

• Search for local causes: pilonidal cyst, hidradenitis suppurativa, or foreign material 1
• Culture early in the course of recurrent infections 1
• Consider decolonization regimen for recurrent S. aureus: 5-day course of intranasal mupirocin twice daily, daily chlorhexidine washes, and decontamination of personal items 1, 2

Culture Recommendations

• Cultures are NOT routinely recommended for typical uncomplicated abscesses 1
• Obtain cultures in: recurrent infections, treatment failures, immunocompromised patients, or when MRSA is suspected 2, 4

Critical Pitfalls to Avoid

• Failing to perform adequate I&D—this is the most important therapeutic intervention and antibiotics cannot substitute for inadequate drainage 2
• Routinely prescribing antibiotics for simple abscesses—this contributes to antibiotic resistance without improving outcomes in uncomplicated cases 4
• Not considering MRSA coverage when antibiotics are indicated in areas with high MRSA prevalence 2
• Using needle aspiration instead of I&D—this has unacceptably low success rates, especially with MRSA (only 8% success) 3

Follow-Up

• Reassess at 48-72 hours to ensure adequate drainage and clinical improvement 4
• If no improvement or worsening occurs, consider inadequate drainage, resistant organisms, or deeper extension requiring further intervention 4