What antibiotic covers Staphylococcus aureus (Staph aureus) and impetigo?

Antibiotics for Staphylococcus aureus and Impetigo

For impetigo caused by Staphylococcus aureus, topical mupirocin is the first-line treatment for localized infections, while oral dicloxacillin, cephalexin, clindamycin, or trimethoprim-sulfamethoxazole are recommended for widespread lesions or when MRSA is suspected. 1, 2

First-Line Treatment Options

Topical Treatment

• Mupirocin: Applied twice daily for 5 days 1

  • Highly effective against S. aureus (including MRSA) and Streptococcus pyogenes 2
  • Demonstrated equal efficacy to oral antibiotics in clinical trials 3
  • Provides high drug concentration at infection site with minimal systemic absorption 4
  • Resistance has been reported, particularly with prolonged use 1

• Retapamulin: Alternative topical option, applied twice daily for 5 days 1

Oral Treatment (for widespread impetigo or when topical therapy is impractical)

For Methicillin-Susceptible S. aureus (MSSA):

• Dicloxacillin or Cephalexin: First-line oral options 1
  • Penicillinase-resistant β-lactams effective against MSSA

For Methicillin-Resistant S. aureus (MRSA) or Penicillin Allergy:

• Clindamycin: 300-450 mg orally four times daily 5, 6

  • Effective against both MRSA and streptococci
  • Caution: 50% of MRSA strains may have inducible or constitutive clindamycin resistance 1

• Trimethoprim-sulfamethoxazole (TMP-SMX): 1-2 double-strength tablets twice daily 5

  • Effective against most community-acquired MRSA
  • Not recommended as single agent for initial treatment if Group A Streptococcus is suspected 1

• Doxycycline: 100 mg twice daily 1, 5

  • Safe in children ≥2 years when used <2 weeks
  • Not recommended for children under 8 years

Treatment Duration and Considerations

• Standard treatment duration is 7 days for oral therapy 1
• For bullous impetigo (exclusively caused by S. aureus), consider longer treatment courses 7, 8
• During outbreaks, systemic antibiotics are preferred over topical to decrease transmission 1
• For patients with recurrent S. aureus infections, consider decolonization with nasal mupirocin (twice daily for 5-7 days) 1

Clinical Pearls and Pitfalls

• Pitfall: Using penicillin alone for impetigo - most S. aureus strains produce penicillinase, rendering penicillin ineffective 1
• Pitfall: Failure to recognize MRSA as a potential pathogen - community-acquired MRSA is increasingly common 1
• Pearl: Culture wound exudates in treatment failures or atypical presentations to guide antibiotic selection 1
• Pearl: Re-evaluate patients on doxycycline or TMP-SMX within 24-48 hours to verify clinical response, as treatment failures have been reported 1
• Caveat: When treating impetigo during outbreaks of post-streptococcal glomerulonephritis, systemic antibiotics should be used to eliminate nephritogenic strains from the community 1

Special Populations

• For children: First-line oral options include dicloxacillin or cephalexin; clindamycin or TMP-SMX for suspected MRSA 1
• For pregnant women: Avoid tetracyclines; β-lactams are generally considered safe 5
• For immunocompromised patients: Consider early systemic therapy and broader coverage 5