What are the first-line and second-line antibiotic treatments for skin local infections?

First-Line and Second-Line Antibiotics for Skin Local Infections

For skin local infections, first-line treatment includes topical mupirocin for limited lesions and oral beta-lactams (dicloxacillin, cephalexin) for more extensive infections, while second-line options include clindamycin, trimethoprim-sulfamethoxazole, or doxycycline, particularly when MRSA is suspected. 1

Classification of Skin Infections

Superficial Infections

• Impetigo: Highly contagious superficial infection characterized by honey-colored crusts 1
• Erysipelas: Well-demarcated, fiery red plaque caused primarily by streptococci 1
• Cellulitis: Acute bacterial infection of dermis and subcutaneous tissue 1
• Folliculitis/Furuncles/Carbuncles: Infections of hair follicles of varying severity 1

First-Line Treatment Options

Topical Therapy (for limited lesions)

• Mupirocin 2% ointment applied three times daily for 5-7 days 1, 2
  • Excellent for impetigo and limited superficial infections 3
  • Particularly effective against Staphylococcus aureus and streptococci 2
• Retapamulin twice daily for 5 days (alternative topical option) 1, 4

Oral Therapy (for more extensive infections)

• Dicloxacillin 500 mg four times daily (first choice for MSSA) 1
• Cephalexin 500 mg four times daily (alternative first-line) 1
• Amoxicillin-clavulanate 875/125 mg twice daily (when broader coverage needed) 1

Second-Line Treatment Options

For MRSA or Penicillin Allergy

• Clindamycin 300-450 mg three times daily 1
  • Effective against both MRSA and streptococci 1
• Trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 double-strength tablets twice daily 1
  • Not recommended as single agent for cellulitis due to potential streptococcal resistance 1
• Doxycycline 100 mg twice daily 1
  • Not recommended for children under 8 years of age 1
• Linezolid 600 mg twice daily (reserved for severe cases) 1

Treatment Algorithm Based on Infection Type

Impetigo

1. Limited lesions: Topical mupirocin or retapamulin 1, 5
2. Multiple lesions: Oral therapy with dicloxacillin or cephalexin 1
3. MRSA suspected: Clindamycin, TMP-SMX, or doxycycline 1

Folliculitis/Furuncles/Carbuncles

1. Small lesions: Warm compresses, topical antibiotics 1
2. Larger lesions: Incision and drainage is primary treatment 1
3. Systemic symptoms or extensive disease: Add oral antibiotics 1
   • Consider MRSA coverage if risk factors present 1

Cellulitis/Erysipelas

1. Mild: Oral beta-lactam (dicloxacillin, cephalexin) 1
2. Moderate/Severe: Consider hospitalization with IV antibiotics 1
3. MRSA suspected: Clindamycin, TMP-SMX, or doxycycline 1

Special Considerations

Pediatric Patients

• Impetigo: Topical mupirocin is first-line for limited lesions 1
• Oral options: Dosing based on weight 1
• Avoid tetracyclines in children under 8 years 1

Animal and Human Bites

• First-line: Amoxicillin-clavulanate 1
• Alternatives: Clindamycin plus fluoroquinolone or TMP-SMX 1

Common Pitfalls to Avoid

• Failure to drain abscesses: Incision and drainage is the primary treatment for abscesses, with antibiotics as adjunctive therapy 1
• Inappropriate MRSA coverage: Overuse of broad-spectrum antibiotics when not indicated 1
• Inadequate duration: 5-10 days of therapy is typically recommended, individualized based on clinical response 1
• Neglecting cultures: Obtain cultures from abscesses and purulent infections, especially with treatment failure or suspected MRSA 1
• Using TMP-SMX alone for cellulitis: May miss streptococcal coverage 1

Prevention of Recurrent Infections

• Maintain good personal hygiene with regular bathing 1
• Keep draining wounds covered with clean, dry bandages 1
• Avoid sharing personal items (razors, towels, etc.) 1
• Consider decolonization strategies for recurrent S. aureus infections 1