In an adult with a cutaneous abscess who has undergone incision and drainage, has no known drug allergies, and no severe renal or hepatic impairment, what are the appropriate oral antibiotic choices for MRSA coverage and when is intravenous therapy indicated?

Antibiotic Choices for Cutaneous Abscesses

Primary Treatment

Incision and drainage is the primary and often sufficient treatment for simple cutaneous abscesses, with antibiotics reserved for specific high-risk situations. 1

When Antibiotics Are Indicated

Antibiotic therapy is mandatory after incision and drainage when ANY of the following conditions are present: 1

• Severe or extensive disease (multiple infection sites) 1
• Rapid progression with associated cellulitis 1
• Signs of systemic illness (fever, tachycardia, hypotension) 1
• Comorbidities or immunosuppression (diabetes, HIV/AIDS, malignancy) 1
• Extremes of age (very young or elderly) 1
• Difficult-to-drain locations (face, hand, genitalia) 1, 2
• Associated septic phlebitis 1
• Lack of response to incision and drainage alone 1

Oral Antibiotic Options for MRSA Coverage

First-Line Oral Agents (Outpatient)

For purulent abscesses requiring antibiotics, the following oral options provide MRSA coverage: 1

Monotherapy options:

• TMP-SMX: 1-2 double-strength tablets twice daily (adults); trimethoprim 4-6 mg/kg/dose every 12 hours (pediatrics) 1
• Doxycycline: 100 mg twice daily (adults); 2 mg/kg/dose every 12 hours for children >45 kg 1
• Minocycline: 200 mg loading dose, then 100 mg twice daily (adults); 4 mg/kg loading, then 2 mg/kg/dose every 12 hours (pediatrics) 1
• Clindamycin: 300-450 mg three times daily (adults); 10-13 mg/kg/dose every 6-8 hours, max 40 mg/kg/day (pediatrics) 1
• Linezolid: 600 mg twice daily (adults); 10 mg/kg/dose every 8 hours, max 600 mg/dose (pediatrics) 1

Important Caveats About Oral Agents

• TMP-SMX and tetracyclines lack reliable activity against β-hemolytic streptococci, so if streptococcal coverage is needed, add amoxicillin 500 mg three times daily 1
• Clindamycin and linezolid cover both MRSA and streptococci as monotherapy 1
• TMP-SMX is pregnancy category C/D and contraindicated in third trimester and children <2 months 1
• Tetracyclines are contraindicated in children <8 years and pregnancy (category D) 1
• Linezolid is significantly more expensive than alternatives with no proven superiority 1
• Clindamycin may increase risk of C. difficile infection compared to other oral agents 1

Duration of Oral Therapy

5-10 days of treatment is recommended, adjusted based on clinical response 1

Intravenous Therapy Indications

IV antibiotics are indicated for patients with systemic toxicity, rapidly progressive infection despite appropriate oral antibiotics, or hospitalized patients with complicated SSTI. 1

IV Antibiotic Options

For hospitalized patients requiring IV therapy: 1

• Vancomycin: 15-20 mg/kg IV every 8-12 hours (adults); 10-15 mg/kg IV every 6 hours (pediatrics) 1, 2
• Linezolid: 600 mg IV twice daily (adults); 10 mg/kg/dose IV every 8 hours (pediatrics) 1
• Daptomycin: 4 mg/kg IV once daily (adults only, not approved for pediatrics) 1
• Telavancin: 10 mg/kg IV once daily (adults) 1
• Clindamycin: 600 mg IV three times daily 1

Duration of IV Therapy

7-14 days is recommended for complicated SSTI, adjusted based on clinical response 1

Special Considerations

Facial Abscesses

Facial abscesses require obligatory antibiotic therapy due to difficulty achieving complete drainage. 2 The recommended empirical regimen is: 2

• Vancomycin PLUS piperacillin-tazobactam, ampicillin-sulbactam, or a carbapenem (imipenem or meropenem) 2
• This broader coverage accounts for polymicrobial flora and anatomic complexity 2

Complex Abscesses (Perianal, Perirectal, IV Drug Use Sites)

Broad-spectrum coverage including Gram-positive, Gram-negative, and anaerobic bacteria is required. 1

Agents to Avoid

Rifampin should NOT be used as monotherapy or adjunctive therapy for SSTI due to rapid resistance development and lack of data supporting benefit 1

Clinical Monitoring

Patients should be reassessed at 48-72 hours for clinical improvement. 2 If no improvement occurs, consider: 2

• Inadequate drainage requiring repeat procedure
• Resistant organisms necessitating culture-directed therapy change
• Deeper infection requiring imaging (CT/MRI) and possible surgical consultation