From the FDA Drug Label
Cefepime has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section. Gram-positive bacteria Staphylococcus aureus (methicillin-susceptible isolates only) NOTE: Most isolates of enterococci, e.g., Enterococcus faecalis, and methicillin-resistant staphylococci are resistant to cefepime.
Cefepime does not cover Methicillin-resistant Staphylococcus aureus (MRSA), as it is only effective against methicillin-susceptible isolates of Staphylococcus aureus. Most isolates of methicillin-resistant staphylococci are resistant to cefepime 1.
From the Research
Cefepime does not reliably cover MRSA (Methicillin-resistant Staphylococcus aureus). Cefepime is a fourth-generation cephalosporin with excellent activity against many gram-negative bacteria, including Pseudomonas aeruginosa, and some gram-positive organisms, but it lacks consistent activity against MRSA. This is because MRSA has altered penicillin-binding proteins (specifically PBP2a) that have low affinity for beta-lactam antibiotics, including cephalosporins like cefepime.
Key Points to Consider
- For MRSA infections, appropriate antibiotic choices include vancomycin (15-20 mg/kg IV every 8-12 hours), daptomycin (4-6 mg/kg IV daily), linezolid (600 mg IV/PO twice daily), or trimethoprim-sulfamethoxazole (5 mg/kg of the trimethoprim component IV/PO twice daily) depending on the site and severity of infection, as supported by recent studies 2.
- In empiric therapy where MRSA is a concern, cefepime would need to be combined with one of these anti-MRSA agents until culture results are available, as suggested by studies on combination therapy 3.
- Always consider local resistance patterns and patient-specific factors when selecting antimicrobial therapy for suspected or confirmed MRSA infections, taking into account the most recent evidence on antibiotic effectiveness and safety 4, 2.
Evidence Summary
The most recent and highest quality study on the treatment of MRSA infections suggests that linezolid may be a preferred antibiotic due to its superiority in clinical and microbiological success without difference in safety compared to vancomycin and daptomycin 2. Another study found that concomitant empiric cefepime improved MRSA BSI clearance when used with vancomycin, indicating a potential role for cefepime in combination therapy 3. However, cefepime alone does not reliably cover MRSA due to its lack of consistent activity against this pathogen.