What antibiotics can be prescribed for a 77-year-old female with impaired renal function (Renal Impairment) and an allergy to macrolide antibiotics for a suspected MRSA (Methicillin-Resistant Staphylococcus Aureus) axillary abscess?

Antibiotic Options for MRSA Axillary Abscess in a 77-Year-Old Female with Renal Impairment and Macrolide Allergy

For a 77-year-old female with renal impairment and macrolide allergy with a suspected MRSA axillary abscess, linezolid 600mg twice daily is the recommended first-line antibiotic therapy. 1

Primary Treatment Options

First-Line Option:

• Linezolid 600mg PO/IV twice daily 1, 2
  • Excellent for MRSA coverage
  • No dose adjustment needed in renal impairment
  • 100% oral bioavailability (same dose for IV and oral)
  • Avoids the nephrotoxicity concerns of vancomycin

Alternative Options:

1. Daptomycin 4-6 mg/kg IV once daily 1, 3

   • Effective against MRSA skin infections
   • Can be used in renal dysfunction patients, though monitoring is required
   • High-dose/short-interval regimens have been reported as safe even in renal dysfunction 3

2. Trimethoprim-sulfamethoxazole (TMP-SMX) 2

   • 1-2 double-strength tablets (160/800 mg) twice daily
   • Dose reduction needed in renal impairment
   • Effective for community-acquired MRSA

3. Ceftaroline 1

   • Dose adjustment required in renal impairment
   • Active against MRSA

Why Not Vancomycin?

Vancomycin should be avoided in this patient due to:

• Presence of renal impairment 1
• Risk of further nephrotoxicity, especially in elderly patients 1
• Difficulty in dosing with fluctuating renal function 1
• Need for frequent drug level monitoring 1

Treatment Algorithm

1. Surgical drainage of the axillary abscess is essential and may be sufficient for small abscesses 2

   • Obtain cultures during drainage to guide definitive therapy

2. Initial empiric therapy while awaiting culture results:

   • Linezolid 600mg twice daily (oral or IV) 1, 2

3. Duration of therapy:

   • For uncomplicated abscess with adequate drainage: 5-10 days 2
   • For complicated infection: 14-21 days 2

4. Monitoring during therapy:

   • If using linezolid: Monitor for myelosuppression, particularly with treatment >2 weeks
   • If using daptomycin: Monitor creatine phosphokinase (CPK) levels
   • If using TMP-SMX: Monitor renal function and electrolytes

Special Considerations for Elderly Patients with Renal Impairment

• Linezolid may require dose adjustment in severe renal dysfunction with prolonged use 4

  • Consider 450mg twice daily if prolonged therapy is needed in severe renal impairment 4

• If daptomycin is used, standard dosing appears safe despite renal dysfunction 3

  • Monitor renal function and CPK levels

• Avoid combination therapy with other nephrotoxic medications

Common Pitfalls to Avoid

• Inadequate surgical drainage of the abscess 2
• Using vancomycin in patients with renal impairment 1
• Assuming beta-lactam/beta-lactamase inhibitor combinations will cover MRSA 2
• Premature discontinuation of antibiotics before complete resolution 2
• Failing to obtain cultures before initiating antibiotics 2
• Using fluoroquinolone monotherapy for MRSA infections due to risk of resistance development 2

Linezolid offers significant advantages in this case due to its excellent MRSA coverage, lack of need for dose adjustment in renal impairment, and availability in both oral and IV formulations, making it the optimal choice for this elderly patient with renal dysfunction and a suspected MRSA axillary abscess.