What is the appropriate cefepime dose for an adult with community‑ or hospital‑acquired pneumonia, how should it be adjusted for impaired renal function, what are the pediatric dosing recommendations, typical treatment duration, and alternatives for severe β‑lactam allergy?

Cefepime Dosing for Pneumonia

Adult Dosing for Community-Acquired Pneumonia (CAP)

Cefepime should be reserved for CAP only when specific risk factors for Pseudomonas aeruginosa are present, not as routine first-line therapy. 1

When to Use Cefepime in CAP

• Add cefepime only if the patient has documented risk factors for P. aeruginosa: structural lung disease (bronchiectasis, cystic fibrosis), recent hospitalization with IV antibiotics within 90 days, or prior respiratory isolation of Pseudomonas 1
• Standard CAP therapy uses ceftriaxone or cefotaxime; cefepime is not a preferred first-line agent 1

Dosing Regimen When Indicated

• Cefepime 2 g IV every 8 hours is the recommended dose for empiric Pseudomonas coverage in CAP 1
• Must be combined with dual antipseudomonal coverage: add ciprofloxacin 400 mg IV every 8 hours or levofloxacin 750 mg IV daily, plus an aminoglycoside (gentamicin or tobramycin 5–7 mg/kg IV daily) for severe infections 1
• Never use cefepime monotherapy for pneumonia—combination therapy is mandatory 1

Hospital-Acquired Pneumonia (HAP) Dosing

Standard HAP Regimen

• Cefepime 2 g IV every 8 hours for patients not at high risk of mortality but with factors increasing likelihood of MRSA or gram-negative pathogens 1
• Combine with vancomycin 15 mg/kg IV every 8–12 hours (target trough 15–20 mg/mL) or linezolid 600 mg IV every 12 hours if MRSA coverage needed 1

High-Risk HAP (Septic Shock or Ventilatory Support)

• Use two antipseudomonal agents: cefepime 2 g IV every 8 hours plus ciprofloxacin 400 mg IV every 8 hours or aminoglycoside 1
• Add MRSA coverage with vancomycin or linezolid 1

Renal Dose Adjustments

Cefepime requires careful dose adjustment in renal impairment to prevent neurotoxicity. 2

Dosing by Creatinine Clearance

• CrCl ≥50 mL/min: 2 g IV every 8 hours (standard dose) 2
• CrCl 30–49 mL/min: 2 g IV every 12 hours 2
• CrCl 11–29 mL/min: 2 g IV every 24 hours 2
• CrCl <10 mL/min or hemodialysis: 2 g IV every 36–48 hours 2

Critical Monitoring in Renal Impairment

• Monitor for neurotoxicity (confusion, muscle jerks, non-convulsive seizures) even with dose adjustment, especially if CrCl <30 mL/min 2
• Trough concentrations >20–30 mg/L indicate accumulation and require immediate dose reduction or drug discontinuation 2
• Symptoms may be subtle and mistaken for ICU delirium—maintain high index of suspicion 2

Pediatric Dosing

Infants and Children (>2 months)

• 50 mg/kg IV every 8 hours for moderate infections 1
• Maximum single dose: 2 g 1
• Use third-generation cephalosporins (ceftriaxone, cefotaxime) as preferred agents; reserve cefepime for resistant organisms or Pseudomonas 1

Severe Pediatric Pneumonia

• 50 mg/kg IV every 8 hours combined with vancomycin or clindamycin if MRSA suspected 1
• Ceftriaxone 100 mg/kg/day remains preferred for most hospitalized children 1

Treatment Duration

Standard Duration

• Minimum 5 days and continue until afebrile for 48–72 hours with no more than one sign of clinical instability 1
• Typical total duration: 7–10 days for uncomplicated pneumonia 1

Extended Duration

• 14–21 days if Legionella, Staphylococcus aureus, or gram-negative enteric bacilli isolated 1
• 10 days minimum for severe microbiologically undefined pneumonia 1

Transition to Oral Therapy

• Switch from IV cefepime when patient is hemodynamically stable (SBP ≥90 mmHg, HR ≤100 bpm), clinically improving, afebrile 48–72 hours, able to take oral medications, and oxygen saturation ≥90% on room air 1
• Oral step-down options: ciprofloxacin 750 mg PO twice daily or levofloxacin 750 mg PO daily if Pseudomonas coverage needed 1
• For non-Pseudomonas infections, transition to amoxicillin 1 g PO three times daily or amoxicillin-clavulanate 875/125 mg PO twice daily 1

Severe β-Lactam Allergy Alternatives

For patients with documented severe penicillin/cephalosporin allergy (anaphylaxis, Stevens-Johnson syndrome), cefepime is contraindicated. 1, 3

Alternative Regimens

• Aztreonam 2 g IV every 8 hours (no cross-reactivity with other β-lactams) plus respiratory fluoroquinolone (levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily) 1, 3
• For MRSA coverage: add linezolid 600 mg IV every 12 hours (preferred over vancomycin in renal impairment) 3
• Fluoroquinolone monotherapy (levofloxacin 750 mg IV daily) acceptable for non-ICU CAP without Pseudomonas risk 1

Critical Pitfalls to Avoid

Inappropriate Use

• Never use cefepime as first-line empiric therapy for CAP—it is reserved for Pseudomonas risk factors only 1
• Ceftriaxone, cefotaxime, or ampicillin-sulbactam are preferred β-lactams for standard CAP 1

Neurotoxicity Risk

• 10% of ICU patients with renal impairment develop cefepime neurotoxicity despite dose adjustment 2
• Symptoms (confusion, myoclonus, seizures) may be non-specific and attributed to other causes 2
• Obtain plasma levels if CrCl <30 mL/min or unexplained neurologic changes occur 2

Inadequate Coverage

• Cefepime monotherapy fails to cover atypical pathogens (Mycoplasma, Chlamydophila, Legionella)—always combine with macrolide or fluoroquinolone 1
• Only 45–65% of patients achieve adequate coverage for pathogens with MIC ≥8 mg/L at standard dosing 2

Timing Errors

• Delaying first antibiotic dose beyond 8 hours increases 30-day mortality by 20–30% 1
• Administer immediately upon diagnosis, ideally in the emergency department 1

Resistance Development

• Obtain blood and sputum cultures before starting antibiotics to enable pathogen-directed de-escalation 1
• Discontinue cefepime if cultures show no Pseudomonas and narrow to ceftriaxone-based regimen 1