What is the treatment for Staphylococcus (Staph) aureus infections?

Treatment for Staphylococcus aureus Infections

The treatment of Staphylococcus aureus infections requires different antibiotics based on methicillin susceptibility, infection type, and severity, with incision and drainage being the primary treatment for cutaneous abscesses. 1

Classification of S. aureus Infections

1. Based on Antibiotic Susceptibility

• Methicillin-susceptible S. aureus (MSSA)
• Methicillin-resistant S. aureus (MRSA)
  • Healthcare-associated MRSA (HA-MRSA)
  • Community-associated MRSA (CA-MRSA)

2. Based on Clinical Presentation

• Skin and soft tissue infections (SSTIs)
  • Simple abscesses/boils
  • Purulent cellulitis
  • Non-purulent cellulitis
  • Complicated SSTIs
• Invasive infections
  • Bacteremia
  • Endocarditis
  • Pneumonia
  • Osteomyelitis

Treatment Algorithm for S. aureus Infections

Skin and Soft Tissue Infections

1. Simple Abscesses/Boils

• Primary treatment: Incision and drainage (A-II) 1
• Antibiotic therapy indicated if:
  • Severe/extensive disease or rapid progression with cellulitis
  • Signs of systemic illness
  • Immunosuppression or comorbidities
  • Extremes of age
  • Abscess in difficult-to-drain area (face, hand, genitalia)
  • Associated septic phlebitis
  • Lack of response to incision and drainage alone 1

2. Purulent Cellulitis (with drainage/exudate, no drainable abscess)

• Empiric therapy for CA-MRSA pending culture results (A-II)
• Duration: 5-10 days, individualized based on clinical response 1
• Outpatient options:
  • Clindamycin 300-450 mg PO TID (A-II)
  • Trimethoprim-sulfamethoxazole (TMP-SMX) (A-II)
  • Doxycycline/minocycline (A-II)
  • Linezolid 600 mg PO twice daily (A-II) 1

3. Non-purulent Cellulitis

• Empiric therapy for β-hemolytic streptococci (A-II)
• Consider MRSA coverage if no response to β-lactam therapy or systemic toxicity
• Duration: 5-10 days, individualized based on clinical response 1

4. Complicated SSTIs (deeper infections, surgical wounds, major abscesses)

• Hospitalization with surgical debridement and broad-spectrum antibiotics
• Empiric MRSA therapy pending culture results:
  • Vancomycin IV (A-I)
  • Linezolid 600 mg IV/PO twice daily (A-I)
  • Daptomycin 4 mg/kg IV once daily (A-I)
  • Telavancin 10 mg/kg IV once daily (A-I)
  • Clindamycin 600 mg IV/PO TID (A-III) 1
• Duration: 7-14 days, individualized based on clinical response 1

Bacteremia and Invasive Infections

MSSA Bacteremia

• First-line: Cefazolin or antistaphylococcal penicillins (e.g., dicloxacillin, flucloxacillin) 2, 3
• Duration: 2 weeks for uncomplicated bacteremia; 4-6 weeks for complicated cases 1

MRSA Bacteremia

• First-line: Vancomycin 30-60 mg/kg/day IV in divided doses (A-I) 1
• Alternatives:
  • Daptomycin 6-10 mg/kg IV once daily 1, 4
  • Teicoplanin (where available) 1
• Duration: 2 weeks for uncomplicated; 4-6 weeks for complicated cases 1

Special Populations

Pediatric Patients

1. Minor skin infections:

   • Mupirocin 2% topical ointment (A-III) 1

2. Hospitalized children with complicated SSTIs:

   • Vancomycin IV (A-II)
   • If stable: Clindamycin 10-13 mg/kg/dose IV every 6-8h if local resistance <10% (A-II)
   • Linezolid: 10 mg/kg/dose PO/IV every 8h for <12 years; 600 mg PO/IV twice daily for >12 years (A-II) 1

3. Important considerations:

   • Tetracyclines should not be used in children <8 years (A-II) 1
   • Daptomycin is indicated for S. aureus bacteremia in pediatric patients (1-17 years) 4

Management of Recurrent SSTIs

Hygiene Measures

• Keep draining wounds covered with clean, dry bandages
• Regular bathing and hand hygiene
• Avoid sharing personal items (razors, linens, towels) 1

Environmental Measures

• Clean high-touch surfaces
• Use appropriate cleaners according to label instructions 1

Decolonization Strategies

• Consider if recurrent SSTI despite optimizing hygiene or ongoing transmission
• Options include:
  • Nasal mupirocin twice daily for 5-10 days
  • Topical body decolonization with chlorhexidine for 5-14 days or dilute bleach baths 1

Common Pitfalls and Caveats

1. Rifampin should not be used as monotherapy for SSTI due to rapid resistance development (A-III) 1

2. Culture collection is essential before starting antibiotics for:

   • Patients receiving antibiotic therapy
   • Severe local infection or systemic illness
   • Inadequate response to initial treatment
   • Suspected outbreaks 1

3. β-lactam antibiotics remain first-line for MSSA infections despite widespread penicillin resistance 2

4. Vancomycin is less effective for MRSA infections with higher MICs within the susceptible range 5

5. Source control is critical for S. aureus bacteremia, including removal of infected devices, drainage of abscesses, and surgical debridement 3

6. All patients with S. aureus bacteremia should undergo echocardiography to rule out endocarditis 3

By following this treatment algorithm and considering the specific characteristics of each infection, clinicians can effectively manage S. aureus infections while minimizing morbidity and mortality.