What are the recommended IV (intravenous) antibiotics for treating Pseudomonas infections?

Recommended IV Antibiotics for Pseudomonas Infections

For Pseudomonas aeruginosa infections, the recommended first-line IV therapy is an antipseudomonal β-lactam such as piperacillin-tazobactam, ceftazidime, or cefepime, with combination therapy recommended for severe infections.

First-Line Options Based on Infection Severity

Non-Critically Ill Patients

• Piperacillin-tazobactam: 4.5g IV every 6 hours 1
• Ceftazidime: 2g IV every 8 hours 2
• Cefepime: 2g IV every 8-12 hours 2

Critically Ill Patients

• Meropenem: 1g IV every 8 hours 1, 3
• Imipenem-cilastatin: 1g IV every 8 hours 1
• Doripenem: 500mg IV every 8 hours 1
• Ceftolozane-tazobactam: 1.5-3g IV every 8 hours (especially for difficult-to-treat strains) 2, 1
• Ceftazidime-avibactam: 2.5g IV every 8 hours 2, 1

Combination Therapy for Severe Infections

For severe Pseudomonas infections, combination therapy is recommended:

1. Antipseudomonal β-lactam + Fluoroquinolone:

   • Piperacillin-tazobactam, cefepime, or meropenem PLUS
   • Ciprofloxacin (preferred) or levofloxacin (750mg dose) 1, 2

2. Antipseudomonal β-lactam + Aminoglycoside:

   • Piperacillin-tazobactam, cefepime, or meropenem PLUS
   • Amikacin (15-20 mg/kg IV once daily) 1, 2

Specific Recommendations by Infection Site

Respiratory Infections (HAP/VAP)

• First choice: Antipseudomonal β-lactam + either azithromycin or a fluoroquinolone 1
• For suspected P. aeruginosa: Piperacillin-tazobactam, cefepime, imipenem, or meropenem PLUS ciprofloxacin or levofloxacin (750mg) 1

Urinary Tract Infections

• First choice: Aminoglycoside monotherapy (if susceptible) 2
• Alternative: Ciprofloxacin (if susceptible) 2

Intra-abdominal Infections

• First choice: Piperacillin-tazobactam 4.5g every 6 hours 1
• Alternative: Meropenem 1g every 8 hours 1

Special Considerations

Carbapenem-Resistant Pseudomonas (CRPA)

• First choice: Ceftolozane-tazobactam (if active in vitro) 1
• Alternative options: Ceftazidime-avibactam, cefiderocol, or imipenem-relebactam 1

Biofilm-Associated Infections

• Higher antibiotic concentrations may be required as P. aeruginosa in biofilms needs 100-1000 times higher concentrations 2

Dosing Considerations

• For meropenem against P. aeruginosa, use 1g every 8 hours (not the lower 500mg dose) 3
• Extended infusion of piperacillin-tazobactam (3.375g IV over 4 hours every 8 hours) may improve outcomes in critically ill patients 4

Monitoring and Duration

• Regular culture and susceptibility testing during therapy is crucial 2
• Monitor local resistance patterns to guide empiric therapy 2
• Treatment duration:
  • Uncomplicated UTI: 5-10 days 2
  • Complicated UTI: 10-14 days 2
  • Nosocomial pneumonia: 7-14 days 2

Important Caveats

• Trimethoprim-sulfamethoxazole (Bactrim) has poor activity against P. aeruginosa due to intrinsic resistance 2
• Ciprofloxacin monotherapy is not recommended for pneumonia due to poor pneumococcal coverage 2
• Resistance development is a concern with carbapenem therapy, with higher rates of resistant P. aeruginosa emerging after treatment compared to ceftazidime or piperacillin-tazobactam 5
• When using aminoglycosides, monitor renal function and drug levels, particularly with prolonged therapy 2

Switching to Oral Therapy

When clinically improved, afebrile for ≥24 hours, with functioning GI tract and decreasing WBC count, consider switching to:

• Ciprofloxacin: 500mg PO twice daily (preferred oral option) 2
• Levofloxacin: 750mg PO daily (alternative) 2