What is the significance of impaired renal function, as evidenced by elevated creatinine, in a patient with Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, presenting with hematuria and proteinuria?

From the Guidelines

The patient with MRSA bacteremia and elevated creatinine of 2.6 with hematuria and proteinuria should be treated with vancomycin (15-20 mg/kg IV every 8-12 hours, adjusted for renal function) as the first-line antibiotic, with close monitoring of serum trough concentrations to achieve target concentrations of 15-20 μg/mL, as recommended by the Infectious Diseases Society of America 1. The management of MRSA bacteremia should include identification and elimination of the primary source of infection, as well as follow-up blood cultures to document clearance of bacteremia 1. Key considerations in the treatment of this patient include:

• Nephrology consultation for evaluation of the kidney injury
• Supportive care to maintain adequate hydration and avoid volume overload
• Monitoring of urine output, daily weight measurements, and frequent electrolyte checks
• Avoidance or dose-adjustment of nephrotoxic medications
• Urinalysis with microscopy, protein-to-creatinine ratio, and renal ultrasound to assess for obstruction or abscess
• Serial creatinine monitoring to track kidney function The use of alternative antibiotics, such as linezolid, may be considered in patients with renal insufficiency or those at risk for vancomycin nephrotoxicity, as suggested by studies on MRSA pneumonia 1. However, the primary goal should be to promptly treat the underlying MRSA infection while minimizing the risk of further kidney injury. Close monitoring of the patient's renal function and adjustment of the treatment plan as needed are crucial to optimize outcomes and reduce the risk of morbidity and mortality.

From the FDA Drug Label

The mean CL T was 9%, 22%, and 46% lower among subjects and patients with mild (CL CR 50 - 80 mL/min), moderate (CL CR 30 - <50 mL/min), and severe (CL CR <30 mL/min) renal impairment, respectively, than in those with normal renal function (CL CR >80 mL/min) Because renal excretion is the primary route of elimination, adjustment of daptomycin for injection dosage interval is necessary in adult patients with severe renal impairment (CL CR <30 mL/min) [see Dosage and Administration (2)

The patient has an elevated creatinine of 2.6 with hematuria and proteinuria, indicating severe renal impairment.

• The creatinine clearance (CL CR) is not explicitly stated, but based on the elevated creatinine, it is likely less than 30 mL/min.
• Daptomycin dosage adjustment is necessary in adult patients with severe renal impairment (CL CR <30 mL/min).
• The patient's MRSA bacteremia requires treatment with daptomycin, but the dosage interval should be adjusted due to the patient's renal impairment 2.

From the Research

Patient Profile

• Elevated creatinine level of 2.6
• Presence of hematuria and proteinuria
• Diagnosed with MRSA bacteremia

Treatment Options

• Vancomycin (VAN) and daptomycin (DAP) are approved as monotherapy for MRSA bacteremia 3
• Combination therapy of daptomycin plus ceftaroline (DAP+CPT) has shown promise in treating MRSA bacteremia 3, 4
• Addition of an antistaphylococcal β-lactam to standard antibiotic therapy with vancomycin or daptomycin did not result in significant improvement in mortality, persistent bacteremia, relapse, or treatment failure 5

Treatment Outcomes

• Daptomycin treatment was associated with significantly lower mortality and higher treatment success compared to vancomycin in patients with MRSA bacteremia and vancomycin minimum inhibitory concentration (MIC) > 1 µg/mL 6
• Vancomycin plus ceftaroline may represent an effective and well-tolerated salvage regimen option for persistent MRSA bacteremia 7
• Combination therapy of DAP+CPT was associated with a numerically lower incidence of clinical failure compared to standard of care in patients with complicated MRSA-BSI 4

Kidney Function

• Acute kidney injury (AKI) occurred in 23% of patients receiving combination therapy with vancomycin or daptomycin and an antistaphylococcal β-lactam, compared to 6% in the standard therapy group 5
• Vancomycin-associated acute kidney injury was observed in 10% of patients receiving vancomycin plus ceftaroline 7