Antibiotic Treatment for Skin Abscess
For simple skin abscesses, incision and drainage alone is the primary treatment and antibiotics are often unnecessary; however, when antibiotics are indicated, trimethoprim-sulfamethoxazole (TMP-SMX) or doxycycline are the preferred first-line oral agents for MRSA coverage, particularly when penicillins or cephalosporins cannot be used. 1
When Antibiotics Are Indicated
Antibiotic therapy should be added to incision and drainage for abscesses with any of the following features 1:
- Severe or extensive disease involving multiple sites or rapid progression with associated cellulitis
- Signs of systemic illness (fever, tachycardia, hypotension)
- Comorbidities or immunosuppression (diabetes, HIV/AIDS, malignancy)
- Extremes of age (very young or elderly patients)
- Difficult-to-drain locations (face, hand, genitalia)
- Associated septic phlebitis
- Lack of response to incision and drainage alone
Oral Antibiotic Options for MRSA Coverage
First-Line Agents (When Beta-Lactams Cannot Be Used)
TMP-SMX 1:
- Adult dose: 1-2 double-strength tablets twice daily for 5-10 days
- Pediatric dose: Trimethoprim 4-6 mg/kg/dose every 12 hours
- Caution: Pregnancy category C/D; avoid in third trimester and children <2 months 1
- Does not cover beta-hemolytic streptococci; add amoxicillin if streptococcal coverage needed 1
Doxycycline 1:
- Adult dose: 100 mg twice daily for 5-10 days
- Pediatric dose: <45 kg: 2 mg/kg/dose every 12 hours
- Contraindication: Children <8 years of age; pregnancy category D 1
- Does not cover beta-hemolytic streptococci; add amoxicillin if streptococcal coverage needed 1
Minocycline 1:
- Adult dose: 200 mg loading dose, then 100 mg twice daily
- Pediatric dose: 4 mg/kg loading dose, then 2 mg/kg/dose every 12 hours
- Same contraindications as doxycycline 1
Alternative Agent with Dual Coverage
- Adult dose: 600 mg twice daily for 5-10 days (oral or IV)
- Pediatric dose: 10 mg/kg/dose every 8 hours (not to exceed 600 mg/dose)
- Covers both MRSA and beta-hemolytic streptococci 1
- Major limitation: Significantly more expensive than alternatives; reserve for patients who cannot tolerate other options 1
- FDA-approved for complicated skin infections with cure rates of 83-90% 2
Special Considerations for Renal Impairment
When renal function is impaired 1:
- TMP-SMX requires dose adjustment in severe renal impairment (CrCl <30 mL/min)
- Doxycycline and minocycline do not require renal dose adjustment, making them preferred tetracyclines in this population
- Linezolid does not require renal dose adjustment 2
- Avoid vancomycin unless hospitalized, as it requires careful monitoring and dose adjustment based on renal function 1
Important Clinical Pitfalls
Do NOT use rifampin as monotherapy or adjunctive therapy for skin abscesses, as resistance develops rapidly without proven benefit 1
Cephalexin is ineffective against MRSA despite being commonly prescribed; a randomized trial showed 87.8% of skin abscess isolates were MRSA, with no benefit from cephalexin over placebo (84.1% vs 90.5% cure rates) 3
Clindamycin resistance is increasing in many communities; it should only be used empirically if local resistance rates are <10% 1
Treatment Duration
- 5-10 days for outpatient treatment of uncomplicated abscesses requiring antibiotics 1
- Individualize based on clinical response, but most patients respond within 7 days 1
When to Hospitalize
Consider inpatient IV therapy with vancomycin, linezolid, or daptomycin for 1:
- Systemic toxicity or hemodynamic instability
- Rapidly progressive infection despite appropriate oral antibiotics
- Complicated skin infections with deeper tissue involvement
- Failed outpatient management