What antibiotic is effective against both Klebsiella and Pseudomonas infections?

Antibiotics Effective Against Both Klebsiella and Pseudomonas

Carbapenems, particularly meropenem, imipenem, or doripenem, are the most reliable antibiotics effective against both Klebsiella and Pseudomonas infections, with newer agents like ceftazidime/avibactam or ceftolozane/tazobactam serving as excellent carbapenem-sparing alternatives. 1

First-Line Treatment Options

Carbapenems

• Meropenem: 1g IV every 8 hours (adjust for renal function)
  • Highly effective against both pathogens
  • Preferred for severe infections and septic shock 1
• Imipenem/cilastatin: 1g IV every 8 hours
  • Excellent activity against both organisms 2, 3
• Doripenem: 500mg IV every 8 hours 1

Carbapenem-Sparing Alternatives

• Piperacillin/tazobactam: 4.5g IV every 6 hours
  • Effective against both pathogens but may have limitations against ESBL-producing Klebsiella 1, 4
• Ceftazidime/avibactam: 2.5g IV every 8 hours + metronidazole (for intra-abdominal infections)
  • Particularly effective against KPC-producing Klebsiella 1, 5
• Ceftolozane/tazobactam: 1.5g IV every 8 hours + metronidazole (for intra-abdominal infections)
  • Especially effective against multidrug-resistant Pseudomonas 1

Special Considerations for Pseudomonas Infections

For confirmed Pseudomonas infections, combination therapy is often recommended initially:

• Antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) plus either:
  • Ciprofloxacin or levofloxacin (750mg dose), OR
  • An aminoglycoside (e.g., amikacin 15-20 mg/kg/day) plus azithromycin 1

Treatment Based on Resistance Patterns

For ESBL-Producing Strains

• Carbapenems remain the treatment of choice
• Ceftazidime/avibactam is an effective alternative 1

For Carbapenem-Resistant Infections

• KPC-producing organisms: Ceftazidime/avibactam or meropenem/vaborbactam 1
• OXA-48-like producers: Ceftazidime/avibactam 1
• Metallo-β-lactamase producers: Limited options; consider ceftazidime/avibactam plus aztreonam or cefiderocol 1, 6

Practical Considerations

• Duration of therapy: Typically 7-14 days depending on infection site, severity, and clinical response 1
• De-escalation: Once susceptibilities are known, narrow therapy to the most appropriate agent 1
• Source control: Critical for successful treatment of intra-abdominal infections 1

Pitfalls to Avoid

1. Extended use of cephalosporins should be discouraged due to selection pressure for ESBL-producing organisms 1
2. Fluoroquinolones should be used cautiously due to increasing resistance rates 1
3. Monotherapy for Pseudomonas may lead to rapid development of resistance; combination therapy is often preferred initially 1
4. Failing to adjust for renal function can lead to toxicity with many of these agents 4, 5

In extremely resistant cases where options are limited, combination therapies may be necessary. However, mortality remains high with pandrug-resistant infections (resistant to all tested antibiotics), though not as high as might be expected 7.