From the Guidelines
Nafcillin is the preferred agent over cefazolin for central nervous system (CNS) methicillin-sensitive Staphylococcus aureus (MSSA) infections, particularly in cases of brain abscess complicating MSSA infections, due to its better blood-brain barrier penetration. For CNS MSSA infections, nafcillin is typically dosed at 2 grams IV every 4 hours, while cefazolin is given at 2 grams IV every 8 hours (dose adjustments needed for renal impairment) 1. Treatment duration typically ranges from 4-6 weeks depending on infection severity, surgical intervention, and clinical response. The historical preference for nafcillin stems from its slightly better blood-brain barrier penetration and lower minimum inhibitory concentration (MIC) against MSSA. However, cefazolin achieves adequate CNS concentrations at standard doses and has advantages including less frequent dosing, fewer adverse effects (particularly hepatotoxicity and interstitial nephritis), and lower cost.
Key Considerations
- Nafcillin is preferred for brain abscess complicating MSSA infections due to its better penetration into the CNS 1.
- Vancomycin should be used if the patient cannot tolerate nafcillin therapy 1.
- The choice between nafcillin and cefazolin should ultimately be guided by patient-specific factors including tolerance, allergies, and comorbidities.
- Therapeutic drug monitoring may be helpful in complicated cases, and adjunctive treatments like surgical drainage should be considered when appropriate.
Treatment Options
- Nafcillin: 2 grams IV every 4 hours, with dose adjustments for renal impairment.
- Cefazolin: 2 grams IV every 8 hours, with dose adjustments for renal impairment.
- Vancomycin: may be used as an alternative to nafcillin in cases of intolerance, with dosing adjusted based on renal function and therapeutic drug monitoring.
From the Research
Comparison of Nafcillin and Cefazolin for CNS MSSA Infections
- The effectiveness of nafcillin versus cefazolin for central nervous system (CNS) methicillin-susceptible Staphylococcus aureus (MSSA) infections is a topic of interest in the medical field.
- A narrative review 2 suggests that dose-optimized cefazolin is likely a safe and effective alternative to antistaphylococcal penicillins, such as nafcillin, for CNS infections due to MSSA.
- Another study 3 found that patients who received cefazolin had a lower risk of mortality and similar odds of recurrent infections compared with nafcillin or oxacillin for MSSA infections complicated by bacteremia.
Treatment Outcomes and Mortality Rates
- A retrospective cohort study 4 compared treatment outcomes with cefazolin versus oxacillin for deep-seated MSSA bloodstream infections and found that the rates of treatment failure were similar among cefazolin-treated and oxacillin-treated patients.
- The study 3 also found that patients who received cefazolin had a 37% reduction in 30-day mortality and a 23% reduction in 90-day mortality compared with patients receiving nafcillin or oxacillin.
CNS Infections and Treatment Approaches
- A review of SA CNS infections 5 highlights the challenges in management and treatment, with poor clinical outcomes and long hospital stays.
- A study on Staphylococcus aureus CNS infections in children 6 found that most patients were treated with nafcillin (MSSA) or vancomycin (MRSA) with or without rifampin, but the study did not directly compare nafcillin and cefazolin for CNS MSSA infections.