What are the recommended injectable antibiotic regimens for patients with pneumonia, including dose and frequency?

Injectable Antibiotic Regimens for Pneumonia

Community-Acquired Pneumonia (CAP)

Pediatric Patients (>3 months)

For hospitalized children with CAP, ampicillin 150-200 mg/kg/day IV every 6 hours or ceftriaxone 50-100 mg/kg/day IV every 12-24 hours are the preferred first-line injectable antibiotics. 1

Standard Empiric Therapy by Clinical Scenario:

Fully immunized children in areas with low penicillin resistance:

• Preferred: Ampicillin 150-200 mg/kg/day IV every 6 hours 1
• Alternatives: Ceftriaxone 50-100 mg/kg/day IV every 12-24 hours (preferred for outpatient parenteral therapy) or cefotaxime 150 mg/kg/day IV every 8 hours 1

Incompletely immunized children, high penicillin resistance areas, or life-threatening infection:

• Preferred: Ceftriaxone 50-100 mg/kg/day IV every 12-24 hours or cefotaxime 150 mg/kg/day IV every 8 hours 1

When atypical pathogens (Mycoplasma, Chlamydophila) are suspected:

• Add IV azithromycin 10 mg/kg on days 1-2 (transition to oral when possible) to β-lactam therapy 1
• Alternative: IV erythromycin lactobionate 20 mg/kg/day every 6 hours 1

For suspected MRSA (empyema, necrotizing pneumonia):

• Add vancomycin 40-60 mg/kg/day IV every 6-8 hours (target trough 15-20 mg/mL) or clindamycin 40 mg/kg/day IV every 6-8 hours to β-lactam therapy 1

Highly resistant S. pneumoniae (MIC ≥4.0 μg/mL):

• Preferred: Ceftriaxone 100 mg/kg/day IV every 12-24 hours 1
• Alternatives: Ampicillin 300-400 mg/kg/day IV every 6 hours or levofloxacin 16-20 mg/kg/day IV every 12 hours (ages 6 months-5 years) or 8-10 mg/kg/day once daily (ages 5-16 years, max 750 mg) 1

Adult Patients - Hospitalized (Medical Ward)

For adults hospitalized with CAP on medical wards, ceftriaxone 1-2 g IV every 12-24 hours plus a macrolide, or a respiratory fluoroquinolone alone are the recommended regimens. 1

Standard regimens:

• Ceftriaxone 1 g IV daily (or 2 g IV daily for severe cases) 1, 2
• OR Cefotaxime 1 g IV every 8 hours 1
• OR Cefuroxime 750-1500 mg IV every 8 hours 1

Note: Research demonstrates ceftriaxone 1 g daily is as effective as 2 g daily for community-acquired pneumonia 2, 3, though 2 g may be preferred for severe cases or resistant organisms 2

Combination therapy (when atypical coverage needed):

• Add IV erythromycin 1 g every 6-8 hours 1
• OR Add IV azithromycin 500 mg daily 1

Alternative monotherapy:

• Levofloxacin 750 mg IV daily 1
• OR Moxifloxacin 400 mg IV daily 1

Adult Patients - Intensive Care Unit

For severe CAP requiring ICU admission, combination therapy with a β-lactam plus either a macrolide or respiratory fluoroquinolone is mandatory. 1

Without Pseudomonas risk:

• Ceftriaxone 1-2 g IV every 12-24 hours or cefotaxime 1 g IV every 8 hours 1
• PLUS macrolide (erythromycin 1 g IV every 6 hours or azithromycin 500 mg IV daily) 1
• OR moxifloxacin 400 mg IV daily or levofloxacin 750 mg IV daily ± cephalosporin 1

With Pseudomonas risk factors:

• Antipseudomonal β-lactam: ceftazidime 1-2 g IV every 8-12 hours, cefepime 2 g IV every 8 hours, piperacillin-tazobactam 4.5 g IV every 6 hours, or meropenem 1 g IV every 8 hours 1
• PLUS ciprofloxacin 400 mg IV every 12 hours or levofloxacin 750 mg IV daily 1
• OR PLUS macrolide + aminoglycoside (gentamicin 5-7 mg/kg IV daily or amikacin 20 mg/kg IV daily) 1

For aspiration pneumonia with anaerobic coverage:

• Amoxicillin-clavulanate 2 g IV every 6 hours 1
• OR clindamycin 600 mg IV every 8 hours + cephalosporin 1

Hospital-Acquired Pneumonia (HAP) / Ventilator-Associated Pneumonia (VAP)

Standard HAP (Not High Risk)

For HAP without MRSA risk factors or high mortality risk, monotherapy with piperacillin-tazobactam 4.5 g IV every 6 hours, cefepime 2 g IV every 8 hours, or levofloxacin 750 mg IV daily is appropriate. 1

Preferred options:

• Piperacillin-tazobactam 4.5 g IV every 6 hours 1
• OR Cefepime 2 g IV every 8 hours 1
• OR Levofloxacin 750 mg IV daily 1
• OR Imipenem 500 mg IV every 6 hours or meropenem 1 g IV every 8 hours 1

HAP with MRSA Risk or High Mortality Risk

For HAP with MRSA risk factors or high mortality risk, dual antipseudomonal coverage plus vancomycin or linezolid is required. 1

Combination regimen (choose TWO from different classes, avoid two β-lactams):

β-lactam options:

• Piperacillin-tazobactam 4.5 g IV every 6 hours 1, 4
• OR Cefepime or ceftazidime 2 g IV every 8 hours 1
• OR Imipenem 500 mg IV every 6 hours or meropenem 1 g IV every 8 hours 1

PLUS one of:

• Levofloxacin 750 mg IV daily or ciprofloxacin 400 mg IV every 8 hours 1
• OR Aminoglycoside: gentamicin or tobramycin 7 mg/kg IV daily (trough <1 μg/mL) or amikacin 20 mg/kg IV daily (trough <4-5 μg/mL) 1

PLUS MRSA coverage:

• Vancomycin 15 mg/kg IV every 8-12 hours (target trough 15-20 μg/mL; consider 25-30 mg/kg loading dose for severe illness) 1
• OR Linezolid 600 mg IV every 12 hours 1

Nosocomial Pneumonia - Pediatric

For pediatric nosocomial pneumonia (ages 2 months-9 months):

• 90 mg/kg IV (80 mg piperacillin/10 mg tazobactam) every 6 hours 4

For pediatric nosocomial pneumonia (>9 months):

• 112.5 mg/kg IV (100 mg piperacillin/12.5 mg tazobactam) every 6 hours 4

Treatment Duration

CAP duration: 5-7 days for responding patients is adequate 1; up to 10-14 days may be needed for bacteremic pneumococcal pneumonia 1

HAP/VAP duration: 7-14 days, with 7 days appropriate for most cases 1, 4

S. aureus pneumonia: Up to 4 weeks may be required if bacteremia is present 1

Critical Pitfalls

• Never delay appropriate empiric therapy - inappropriate initial antibiotics significantly increase mortality in HAP/VAP 1
• Assess MRSA risk factors carefully - prior IV antibiotics within 90 days, local MRSA prevalence >20%, or prior MRSA colonization mandate MRSA coverage 1
• Avoid fluoroquinolone monotherapy in ICU - combination therapy is mandatory for severe CAP 1
• Monitor vancomycin troughs - target 15-20 μg/mL for serious infections 1
• De-escalate based on cultures - narrow therapy once pathogens identified to minimize resistance 1