What oral antibiotics are recommended for treating infections?

Oral Antibiotics for Treating Infections

For skin and soft tissue infections, the choice of oral antibiotic depends primarily on whether the infection is purulent or non-purulent, and whether MRSA is suspected or confirmed.

Skin and Soft Tissue Infections (SSTIs)

Purulent Infections (Abscesses, Purulent Cellulitis)

For purulent SSTIs where MRSA is suspected, first-line oral options include:

• Clindamycin 300-450 mg three times daily 1
• Trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 double-strength tablets twice daily 1
• Doxycycline 100 mg twice daily 1, 2
• Linezolid 600 mg twice daily 1

Duration: 5-10 days, individualized based on clinical response 1

Non-Purulent Infections (Cellulitis without drainage)

For non-purulent cellulitis, target β-hemolytic streptococci with:

• Cephalexin 500 mg four times daily 1
• Dicloxacillin 500 mg four times daily 1
• Amoxicillin-clavulanate 875/125 mg twice daily 1
• Penicillin V or amoxicillin 1

If no response to β-lactam therapy, add MRSA coverage as above 1

Impetigo

For impetigo in adults and children:

• Dicloxacillin 250 mg four times daily (adults) or 12 mg/kg/day in 4 divided doses (children) 1
• Cephalexin 250 mg four times daily (adults) or 25 mg/kg/day in 4 divided doses (children) 1
• Mupirocin 2% topical ointment three times daily for limited lesions 1

Methicillin-Susceptible Staphylococcus aureus (MSSA)

Dicloxacillin 500 mg four times daily is the oral agent of choice for MSSA 1

Alternative options:

• Cephalexin 500 mg four times daily 1
• Clindamycin 300-450 mg three times daily 1

Animal and Human Bites

For animal bites, amoxicillin-clavulanate 500-875 mg twice daily is first-line oral therapy 1

Alternative oral regimens:

• Doxycycline 100 mg twice daily 1
• Penicillin 500 mg four times daily plus dicloxacillin 500 mg four times daily 1
• Fluoroquinolones (ciprofloxacin 500-750 mg twice daily, moxifloxacin 400 mg daily) 1

For human bites, amoxicillin-clavulanate remains first-line 1

Diabetic Wound Infections

Mild Infections

Oral options for mild diabetic foot infections:

• Dicloxacillin 1
• Cephalexin 1
• Levofloxacin 1, 3
• Amoxicillin-clavulanate 1
• Doxycycline 1
• TMP-SMX for suspected/confirmed MRSA 1

Moderate to Severe Infections

These typically require parenteral therapy initially, with potential transition to oral agents like levofloxacin or linezolid 1

Anthrax (Community-Acquired Cutaneous)

For cutaneous anthrax:

• Penicillin V 200-500 mg four times daily 1
• Amoxicillin 500 mg every 8 hours 1

For inhalational anthrax post-exposure prophylaxis: doxycycline 100 mg twice daily for 60 days 2

Important Caveats

Incision and drainage is the primary treatment for cutaneous abscesses; antibiotics are adjunctive 1. Antibiotics are indicated when abscesses are associated with severe/extensive disease, systemic illness, immunosuppression, extremes of age, difficult-to-drain locations, or lack of response to drainage alone 1.

Clindamycin resistance: Be aware of potential cross-resistance with erythromycin-resistant strains and inducible resistance in MRSA 1. Use only if local resistance rates are low (e.g., <10%) 1.

Tetracyclines (doxycycline, minocycline) should not be used in children <8 years of age 1.

TMP-SMX has limited activity against β-hemolytic streptococci, so if dual coverage is needed, combine with a β-lactam like amoxicillin 1.

Rifampin should not be used as monotherapy or adjunctive therapy for SSTIs 1.