What is the antimicrobial spectrum and typical dosing of cefepime?

Cefepime Coverage and Dosing

Cefepime is a fourth-generation cephalosporin with broad-spectrum activity against both gram-positive organisms (similar to cefotaxime) and gram-negative organisms including Pseudomonas aeruginosa (similar to ceftazidime), with enhanced stability against many beta-lactamases.

Antimicrobial Spectrum

Gram-Positive Coverage

• Staphylococcus aureus (methicillin-susceptible): Excellent activity, 4-fold more potent than ceftazidime 1, 2
• Streptococcus pneumoniae: Highly active including penicillin-resistant strains (97.4% susceptible, MIC90 = 1 μg/mL) 3
• Does NOT cover: Methicillin-resistant S. aureus (MRSA), Enterococcus species 1, 2

Gram-Negative Coverage

• Enterobacteriaceae: 99.5% susceptible (MIC90 = 0.25 μg/mL), including many ESBL-producing strains (92.5-93.8% susceptible) 3
• Pseudomonas aeruginosa: 85.2% susceptible, comparable to imipenem 3
• Enhanced activity against: Enterobacter species and other AmpC-producing organisms due to poor beta-lactamase induction 2, 4
• Limited activity: Bacteroides and other anaerobes 1

Key Resistance Mechanisms

Cefepime is stable against many plasmid- and chromosomally-mediated beta-lactamases and is a poor inducer of AmpC beta-lactamases 2, 4. However, it can be hydrolyzed by some extended-spectrum beta-lactamases, though to a lesser extent than third-generation cephalosporins 4.

Standard Dosing Regimens

Adults (Normal Renal Function: CrCl >60 mL/min)

Per FDA labeling 5:

Indication	Dose	Frequency	Duration
Moderate-severe pneumonia	1-2 g IV	Every 8-12 hours	10 days
Pneumonia with Pseudomonas	2 g IV	Every 8 hours	10 days
Febrile neutropenia	2 g IV	Every 8 hours	7 days or until neutropenia resolves
Mild-moderate UTI	0.5-1 g IV	Every 12 hours	7-10 days
Severe UTI	2 g IV	Every 12 hours	10 days
Skin/soft tissue infections	2 g IV	Every 12 hours	10 days
Complicated intra-abdominal (with metronidazole)	2 g IV	Every 8-12 hours	7-10 days

Pediatric Dosing (>2 months to 16 years, Normal Renal Function)

Standard dose: 50 mg/kg/dose IV every 12 hours 5

• Febrile neutropenia: 50 mg/kg/dose IV every 8 hours 5
• Maximum single dose: 2 g 6
• For Pseudomonas infections: 50 mg/kg/dose IV every 8 hours (maximum 2 g/dose) 6

Neonatal Dosing 6

Gestational age <36 weeks: 30 mg/kg/dose IV every 12 hours
Gestational age ≥36 weeks: 50 mg/kg/dose IV every 12 hours

Administration

Administer intravenously over approximately 30 minutes 5. Extended infusions (3-hour) or continuous infusions may improve pharmacodynamic target attainment, particularly for resistant organisms 7, 8.

Renal Dose Adjustment

Critical: Dose adjustment required when CrCl ≤60 mL/min 5. Failure to adjust doses in renal impairment significantly increases neurotoxicity risk 5, 9.

Clinical Guideline Applications

Hospital-Acquired Pneumonia

Cefepime is recommended as empiric monotherapy for HAP in patients without MRSA risk factors 10:

• Dose: 2 g IV every 8 hours
• Combination with vancomycin or linezolid if MRSA risk factors present

Complicated Intra-Abdominal Infections

Acceptable for pediatric and adult patients 11:

• Dose: 2 g IV every 8 hours (adults); 50 mg/kg/dose every 8 hours (pediatrics)
• Must combine with metronidazole for anaerobic coverage

Nosocomial Endocarditis

For early prosthetic valve endocarditis or catheter-associated infections 12:

• Pediatric: 100-150 mg/kg/day divided every 8-12 hours (maximum 6 g/day)
• Combined with vancomycin and gentamicin (±rifampin if prosthetic material)

Gram-Negative Endocarditis

For enteric bacilli 12:

• Pediatric: 100-150 mg/kg/day divided every 8 hours (maximum 6 g/day)
• Must combine with aminoglycoside (gentamicin, tobramycin, or amikacin)

Critical Safety Considerations

Neurotoxicity Risk

Cefepime-induced neurotoxicity (CIN) is significantly underrecognized 5, 9. The ACORN trial demonstrated 21% fewer delirium- and coma-free days with cefepime versus piperacillin-tazobactam 9.

High-risk patients:

• Age ≥65 years
• Renal impairment (especially if doses not adjusted)
• Pre-existing neurological conditions
• High plasma concentrations (>20-30 mg/L)

If neurotoxicity occurs, discontinue cefepime immediately 5.

Mortality Concerns

Recent meta-analysis showed 94.4% posterior probability of increased mortality with cefepime versus other beta-lactams (OR 1.10), with 98.6% probability in published peer-reviewed trials (OR 1.17) 13. This warrants careful consideration when alternative agents are available.

Therapeutic Drug Monitoring

Strongly consider TDM in:

• Critically ill patients 7, 8
• Renal dysfunction
• Augmented renal clearance
• Infections with resistant organisms (MIC >4 mg/L)

Target: Free steady-state concentrations 100% time above MIC; avoid concentrations >30 mg/L to minimize neurotoxicity 7.

Optimized Dosing Strategies

For resistant organisms or critically ill patients 7, 8:

• Extended infusions (3-hour): Achieve 2-fold higher breakpoints than 30-minute infusions
• Continuous infusion: 2 g loading dose, then 4 g/day continuous infusion achieves 96% target attainment for Enterobacterales (MIC 4 mg/L) and 93% for P. aeruginosa (MIC 8 mg/L) with lower neurotoxicity risk 7

In pediatric critical care: Extended or continuous infusions strongly recommended for Pseudomonas and resistant pathogens 8.