Cefepime for Gram-Positive Bacilli
Cefepime has limited and unreliable activity against Gram-positive bacilli and should not be used as primary therapy for these organisms.
Spectrum Against Gram-Positive Organisms
Cefepime's activity is primarily directed at Gram-negative bacteria, with only modest coverage of select Gram-positive cocci—not bacilli 1, 2. The FDA label specifies activity against Gram-positive cocci including methicillin-susceptible Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, and viridans group streptococci, but makes no mention of Gram-positive bacilli 1.
Key Limitations for Gram-Positive Coverage
Gram-positive bacilli are not included in cefepime's approved spectrum of activity according to the FDA label, which lists only Gram-positive cocci as susceptible organisms 1.
Cefepime lacks activity against important Gram-positive bacilli such as Bacillus species and Corynebacterium jeikeium, which require vancomycin for treatment 3.
The 2002 IDSA guidelines note that while some antibiotics like ticarcillin, piperacillin, and carbapenems have excellent activity against most viridans streptococci strains, cefepime (but not ceftazidime) has activity against these organisms—but this refers to streptococci (cocci), not bacilli 3.
Clinical Implications
For suspected Gram-positive bacilli infections, vancomycin is the appropriate empiric choice, as organisms like Bacillus species and C. jeikeium are susceptible only to vancomycin 3.
When cefepime is used for empiric therapy in febrile neutropenia or serious infections, it should be combined with vancomycin if Gram-positive coverage is needed, particularly for catheter-related infections or known colonization with resistant Gram-positive organisms 3.
The IDSA guidelines recommend incorporating vancomycin into initial regimens for high-risk patients when Gram-positive infections are suspected, then discontinuing after 24-48 hours if no such infection is identified 3.
Common Pitfalls
Do not rely on cefepime for Gram-positive bacilli coverage—its spectrum is designed for Gram-negative organisms and select Gram-positive cocci only 1, 2.
Cefepime is inactive against enterococci and methicillin-resistant staphylococci, further limiting its Gram-positive utility 1, 2.
When treating mixed infections or empiric therapy requiring both Gram-positive and Gram-negative coverage, cefepime must be combined with an agent active against Gram-positive organisms such as vancomycin or linezolid 3.