What is the initial treatment approach for bacterial skin infections?

Initial Treatment Approach for Bacterial Skin Infections

The initial treatment approach for bacterial skin infections should include incision and drainage for abscesses, and empiric antibiotic therapy with agents active against gram-positive organisms such as penicillinase-resistant penicillins, cephalosporins, or macrolides for non-purulent infections. 1, 2

Classification of Skin Infections

Bacterial skin infections can be classified based on:

• Necrotizing vs. non-necrotizing character 2
• Anatomical extension (superficial vs. deep) 2
• Purulent vs. non-purulent characteristics 2
• Clinical severity (uncomplicated vs. complicated) 2

Common Types of Bacterial Skin Infections

• Impetigo: Caused primarily by Streptococcus β-hemolítico and/or Staphylococcus aureus 1, 3
• Erysipelas: Caused mainly by streptococci, especially Streptococcus pyogenes 1, 4
• Cellulitis: Most common skin infection (59.1% of cases), caused by streptococci or staphylococci 1, 4
• Folliculitis: Inflammation of hair follicles, commonly caused by Staphylococcus 4
• Furuncles and carbuncles: Deeper infections of hair follicles, usually caused by Staphylococcus 4

Initial Treatment Approach

For Non-Purulent Infections (Cellulitis, Erysipelas)

1. Empiric antibiotic therapy targeting gram-positive organisms 2, 1:

   • First-line options: Beta-lactams such as cephalexin (500 mg orally 3-4 times daily) or dicloxacillin (500 mg orally 4 times daily) 5, 1
   • For penicillin allergic patients: Clindamycin or doxycycline 6, 1
   • If MRSA is suspected: Consider vancomycin, linezolid, or daptomycin 2, 1

2. Severity assessment to determine route of administration:

   • Mild infections without significant comorbidities: Oral antibiotics 1
   • Moderate to severe infections: Parenteral antibiotics 1, 2

For Purulent Infections (Abscesses, Furuncles, Carbuncles)

1. Incision and drainage is the primary treatment 1, 4

   • For simple abscesses, incision and drainage alone may be sufficient without antibiotics 1

2. Antibiotic therapy is indicated if:

   • There are systemic signs of infection 1
   • The patient is immunocompromised 1, 2
   • There is significant surrounding cellulitis 1
   • The abscess is in a critical location 1
   • Adequate drainage cannot be achieved 1

3. When antibiotics are needed:

   • For simple infections: Coverage for Staphylococcus aureus, including consideration of MRSA based on local prevalence 1, 3
   • For complex abscesses: Broader coverage including gram-negative and anaerobic organisms 1

Special Considerations

Immunocompromised Patients

• Broader empiric coverage is recommended for immunocompromised patients 2
• Aggressive diagnostic approach with aspiration and/or biopsy of skin lesions for histological and microbiological evaluation 2
• For neutropenic patients: Vancomycin plus antipseudomonal antibiotics such as cefepime, a carbapenem, or piperacillin-tazobactam 2

Animal and Human Bites

• Higher risk of infection: 30-50% of cat bites, 5-25% of dog bites, and 20-25% of human bites become infected 1
• Recommended empiric therapy: Amoxicillin-clavulanate is the preferred agent 2, 1
• Alternative options: Ampicillin-sulbactam, or a combination of a fluoroquinolone plus metronidazole 2

Common Pitfalls to Avoid

• Failure to perform incision and drainage for purulent collections, which is essential regardless of antibiotic therapy 1, 2
• Underestimating the importance of clinical reassessment after 48-72 hours to evaluate response to initial therapy 1
• Not considering MRSA in areas with high prevalence or in patients with risk factors 1, 3
• Inadequate empiric coverage in immunocompromised patients or those with complex infections 2
• Prolonged antibiotic courses when shorter durations (7-14 days) are typically sufficient for most uncomplicated infections 2

Duration of Treatment

• Non-necrotizing infections: Typically 7-14 days 2
• Necrotizing infections: Continue until no further debridement is needed, clinical improvement is observed, and fever has resolved for 48-72 hours 1

By following these guidelines, clinicians can effectively manage bacterial skin infections while minimizing complications and optimizing patient outcomes.