From the Guidelines
Cefazolin is the preferred treatment for persistent Methicillin-Sensitive Staphylococcus aureus (MSSA) bacteremia.
Key Considerations
- The choice of antibiotic therapy for Staphylococcus aureus bacteremia (SAB) depends on whether the isolate is methicillin-susceptible or -resistant, with beta-lactams showing superior outcomes for MSSA bloodstream infections compared to vancomycin 1.
- Cefazolin is a suitable option for MSSA bacteremia, despite concerns about the cefazolin inoculum effect (CzIE), which may decrease its efficacy in some isolates.
- Recent observational data suggest similar efficacy, or even a trend towards superiority of cefazolin over anti-staphylococcal penicillins (ASPs), such as cloxacillin 1.
- The preferable safety profile of cefazolin compared to ASPs, along with large-scale observational data supporting its efficacy, make it a comfortable choice for most patients with MSSA bacteremia 1.
Treatment Approach
- Beta-lactam therapy, such as cefazolin, should be considered as the primary treatment for MSSA bacteremia.
- In areas with high MRSA prevalence, an empiric combination approach (e.g., vancomycin or daptomycin and a beta-lactam) may be considered to provide optimal upfront therapy for both MSSA and MRSA, but this approach is still debated 1.
From the Research
Treatment Options for Persistent Methicillin-Sensitive Staphylococcus aureus (MSSA) Bacteremia
The treatment for persistent MSSA bacteremia is not well-established, but several options are available:
- Modification of antimicrobial therapy, in conjunction with source control and infectious diseases consultation, may be necessary to sterilize blood cultures in patients with persistent MSSA bacteremia 2
- Dual β-lactam regimens may be considered for persistent MSSA bacteremia, although data are limited to case reports and case series 2
- Cefazolin and cloxacillin are commonly used antibiotics for the treatment of MSSA bacteremia, and treatment with cefazolin is not significantly different from treatment with cloxacillin 3
- Other beta-lactams, including second and third generation cephalosporins, might be associated with higher mortality 3
Considerations for Treatment
When selecting a treatment regimen for persistent MSSA bacteremia, the following factors should be considered:
- Recent exposure to antibiotics
- Source control
- Available synergy and clinical data
- The potential for combination therapy, such as the use of multiple antibiotics together 4, 5
Limitations of Current Evidence
There is limited guidance on the best approach for managing patients with persistent MSSA bacteremia, and further research is needed to establish a preferred treatment regimen 2, 6