What is the recommended treatment for infections caused by Pseudomonas aeruginosa?

Treatment of Pseudomonas aeruginosa Infections

For infections caused by Pseudomonas aeruginosa, the recommended first-line treatment is an antipseudomonal β-lactam (such as piperacillin-tazobactam, ceftazidime, cefepime, or a carbapenem) with consideration for combination therapy with an aminoglycoside or fluoroquinolone in severe or complicated infections. 1

First-Line Treatment Options

Intravenous Options:

• Antipseudomonal β-lactams:
  • Piperacillin-tazobactam: 3.375-4.5g IV every 6 hours 2
  • Ceftazidime: 2g IV every 8 hours 1
  • Cefepime: 2g IV every 8-12 hours 1
  • Carbapenems (imipenem or meropenem) 3

Combination Therapy Considerations:

• For severe infections or nosocomial pneumonia:
  • Add an aminoglycoside (e.g., tobramycin 5-7mg/kg/day) 1
  • OR add a fluoroquinolone (ciprofloxacin or levofloxacin) 1

Oral Step-Down Options:

• Ciprofloxacin 500mg twice daily or Levofloxacin 750mg daily (when susceptible) 1

Treatment Duration

• Uncomplicated infections: 7 days
• Complicated infections: 10-14 days
• Nosocomial pneumonia: 7-14 days 3, 1

Special Considerations

For Multidrug-Resistant P. aeruginosa:

• Consider newer agents:
  • Ceftolozane-tazobactam: 1.5-3g IV every 8 hours
  • Ceftazidime-avibactam: 2.5g IV every 8 hours
  • Colistin: 5 mg/kg IV loading dose, then 2.5 mg/kg IV every 12 hours 1

For Specific Infection Sites:

Nosocomial Pneumonia:

• Piperacillin-tazobactam 4.5g every 6 hours PLUS an aminoglycoside 2
• Treatment duration: 7-14 days
• Continue aminoglycoside in patients from whom P. aeruginosa is isolated 3

Urinary Tract Infections:

• Antipseudomonal β-lactam monotherapy is usually sufficient 1
• Consider removing or replacing urinary catheters if present

Skin and Soft Tissue Infections:

• Documented infections should be treated based on antimicrobial susceptibilities 3
• Duration: 7-14 days 3

Monitoring and Response Assessment

• Clinical response should be evident within 48-72 hours of appropriate therapy
• If no improvement after 72 hours, consider repeat cultures and antibiotic adjustment 1

Important Considerations

Resistance Concerns:

• Check local resistance patterns to guide therapy choices 1
• Avoid fluoroquinolones for empirical treatment if local resistance rate is >10% or if patient has used fluoroquinolones in the last 6 months 1
• Synergy has been demonstrated between piperacillin-tazobactam and aminoglycosides in in vitro studies 4

Dosing in Renal Impairment:

• Adjust dosing based on creatinine clearance:
  • For creatinine clearance 20-40 mL/min: reduce dose of piperacillin-tazobactam to 2.25g every 6 hours
  • For creatinine clearance <20 mL/min: further reduce to 2.25g every 8 hours 2

Biofilm Considerations:

• P. aeruginosa readily forms biofilms, particularly in catheterized patients
• Short-course systemic antibiotic therapy can postpone biofilm infections for up to 1-2 weeks 1

Conclusion

When treating P. aeruginosa infections, the choice of antibiotics should be guided by susceptibility testing, site of infection, severity, and patient factors. Combination therapy should be considered for severe infections, particularly nosocomial pneumonia. Monitor for clinical response and be prepared to adjust therapy based on culture results and clinical progression.