What are the recommended antibiotics (Abx) for Pseudomonas aeruginosa infections?

Recommended Antibiotics for Pseudomonas aeruginosa Infections

For P. aeruginosa infections, the recommended first-line treatment is piperacillin-tazobactam (3.375-4.5g IV q6h) as monotherapy for susceptible strains, or in combination with an aminoglycoside or fluoroquinolone for severe infections. 1, 2

First-Line Antipseudomonal Agents

• Piperacillin-tazobactam: 3.375g IV q6h for standard infections; 4.5g IV q6h for nosocomial pneumonia 2
• Ceftazidime: 2g IV q8h 1
• Cefepime: 2g IV q8-12h 1
• Meropenem: 1g IV q8h (when treating infections caused by P. aeruginosa) 3
• Ciprofloxacin: 400mg IV q8h or 750mg PO q12h 1

Treatment Approach Based on Infection Severity

Non-Severe Infections

• Monotherapy with a highly active β-lactam is generally preferred for susceptible isolates 1
• Options include:
  • Piperacillin-tazobactam 2
  • Ceftazidime 1
  • Cefepime 1
  • Meropenem 3

Severe Infections

• Combination therapy is recommended for critically ill patients 1
• Preferred combinations:
  • Antipseudomonal β-lactam + ciprofloxacin or levofloxacin 1, 4
  • Antipseudomonal β-lactam + aminoglycoside (amikacin, gentamicin, or tobramycin) 4, 1
• For nosocomial pneumonia: piperacillin-tazobactam at 4.5g IV q6h plus an aminoglycoside 2
• P. aeruginosa infection may be treated with two antipseudomonal drugs to reduce the chance of treatment failure 5

Treatment for Resistant Strains

• For carbapenem-resistant P. aeruginosa (CRPA):
  • Ceftolozane-tazobactam is recommended as first-line therapy 6
  • Ceftazidime-avibactam may be considered as an alternative if resistance to ceftolozane-tazobactam is present 6
• For multidrug-resistant strains:
  • Colistin or polymyxin B are options for highly resistant isolates 1
  • Combination therapy should be considered to prevent resistance development 6, 4

Route of Administration and Duration

• Intravenous route is preferred for severe infections 5
• Oral route (ciprofloxacin) can be used for less severe infections if the patient is able to eat 5
• Switch from IV to oral therapy when the patient is clinically stable (usually by day 3) 5
• Treatment duration:
  • 7-10 days for most infections 1
  • 10-14 days for P. aeruginosa pneumonia or bloodstream infections 1
  • For COPD exacerbations with P. aeruginosa: 7-10 days 5

Special Considerations

• For patients with cystic fibrosis:

  • Higher doses of antibiotics are often required 5
  • Inhaled antibiotics (colistin, tobramycin) may be used for maintenance therapy 7
  • Aggressive early treatment may delay development of chronic infection 7

• For immunocompromised patients:

  • Combination therapy is strongly recommended 4
  • An antipseudomonal beta-lactam plus either ciprofloxacin or an aminoglycoside 4

Common Pitfalls and Caveats

• Avoid fluoroquinolone monotherapy for severe infections due to high risk of resistance development 4
• Consider extended-infusion dosing of piperacillin-tazobactam (3.375g IV over 4 hours q8h) for critically ill patients, which has been associated with lower mortality and shorter hospital stays 8
• Aminoglycoside monotherapy should only be considered for uncomplicated urinary tract infections 1
• When susceptibility results become available, de-escalate to monotherapy if appropriate 5
• For patients who have received recent antibiotic therapy (within 90 days), consider using an alternative class of antibiotics to prevent resistance development 1
• Regular monitoring of aminoglycoside levels is necessary to minimize toxicity while ensuring efficacy 4