What antibiotics are used to treat skin abscesses?

Antibiotic Treatment for Skin Abscesses

For skin abscesses, incision and drainage is the primary treatment for simple abscesses, while antibiotics are recommended for complex abscesses or those with significant cellulitis, systemic symptoms, or in immunocompromised patients. 1

Simple vs. Complex Abscesses

Simple Abscesses

• Defined as having induration and erythema limited to a defined area
• Do not extend into deeper tissues or have multiloculated extension
• Treatment: Incision and drainage alone is sufficient; antibiotics are not needed 1

Complex Abscesses

• Include perianal, perirectal, and abscesses at IV drug injection sites
• Treatment: Incision and drainage plus antibiotic therapy, especially if:
  • Systemic signs of infection are present
  • Patient is immunocompromised
  • Source control is incomplete
  • Significant cellulitis surrounds the abscess 1

Antibiotic Selection Algorithm

First-line Options:

• For standard skin infections (MSSA likely):

  • Cephalexin 500 mg orally 4 times daily for 5-7 days 2
  • Dicloxacillin 500 mg orally 4 times daily for 5-7 days 2

• If MRSA is suspected or prevalent in community:

  • TMP-SMX 1-2 DS tablets (160/800 mg) twice daily for 5-7 days 2
  • Doxycycline 100 mg orally twice daily for 5-7 days 2
  • Clindamycin 300-450 mg orally 3 times daily for 5-7 days 2

For Severe Infections (requiring hospitalization):

• Vancomycin 15 mg/kg IV every 12 hours 2
• Linezolid 600 mg IV/PO every 12 hours 2, 3
• Consider adding gram-negative coverage if risk factors present 2

Treatment Duration

• Mild infections: 5-7 days
• Moderate infections: 7-10 days
• Severe infections: 10-14 days 2

Evidence Supporting Antibiotic Use

Recent high-quality evidence supports the use of antibiotics for abscesses after drainage:

• A 2017 study showed that clindamycin or TMP-SMX in conjunction with incision and drainage improved short-term outcomes compared to incision and drainage alone 4
• For MRSA abscesses specifically, a 10-day course of TMP-SMX was superior to a 3-day course in preventing treatment failure and recurrence 5
• Antibiotics have shown benefit across all lesion sizes, with greatest effect in patients with history of MRSA, fever, or positive MRSA culture 6

Special Considerations

Pediatric Patients

• Avoid doxycycline in children under 8 years due to risk of dental staining 2
• Cephalexin suspension is well-accepted by young children 7

Pregnant Patients

• Avoid doxycycline 2
• Consider alternative antibiotics based on safety profile

Immunocompromised Patients

• May require broader coverage (e.g., vancomycin plus piperacillin-tazobactam or a carbapenem) 2
• May need extended treatment duration based on clinical response 2

Important Caveats

1. Obtain cultures when possible to guide targeted therapy, especially in recurrent cases
2. Consider local resistance patterns when selecting empiric therapy
3. Monitor for clinical improvement within 48-72 hours; if none, reassess diagnosis and consider changing antibiotics 2
4. Address predisposing factors to prevent recurrence (underlying skin conditions, edema, hygiene practices) 2
5. Cephalexin is not effective against MRSA - use appropriate alternatives if MRSA is suspected 2

Remember that while older studies suggested antibiotics might be unnecessary after drainage of uncomplicated abscesses 8, more recent evidence supports their use, particularly for MRSA infections, which now account for a significant percentage of skin abscesses.