What are the recommended antibiotics (Abx) for treating Enterobacter cloacae infections?

Recommended Antibiotics for Enterobacter cloacae Infections

Carbapenems are the first-line treatment for Enterobacter cloacae infections, with meropenem and imipenem being the most effective options. 1

First-line Treatment Options

Carbapenems

• Meropenem: Highly effective against E. cloacae, including many resistant strains 1, 2

  • Dosing: 1g IV every 8 hours (adjust for renal function)
  • Preferred for severe infections and septic shock

• Imipenem: Alternative carbapenem with good activity against E. cloacae 1

  • Dosing: 500mg IV every 6 hours

• Ertapenem: May be considered for less severe infections, but not recommended for critically ill patients 3

  • Dosing: 1g IV every 24 hours

Newer β-lactam/β-lactamase inhibitor combinations

• Ceftazidime-avibactam: Effective for E. cloacae infections, including some carbapenem-resistant strains 1, 4
  • Dosing: 2.5g (2g ceftazidime + 0.5g avibactam) IV every 8 hours
  • Clinical cure rate of 84.6% reported for E. cloacae infections 4

Second-line Treatment Options

For less severe infections or based on susceptibility testing:

• Cefepime: May be effective against some strains, particularly when other options are limited 5

  • Dosing: 1-2g IV every 8-12 hours
  • Better than other cephalosporins against E. cloacae due to stability against AmpC β-lactamases

• Aminoglycosides (e.g., amikacin): Can be used as part of combination therapy 3, 6

  • Dosing: 15-20 mg/kg IV once daily
  • Particularly useful in combination with meropenem for resistant strains

Treatment Considerations Based on Infection Site

Bloodstream Infections

• Carbapenems are strongly preferred over other β-lactams 2
• Studies show lower mortality rates (9.4% vs 29.5%) and fewer breakthrough infections with carbapenem therapy compared to non-carbapenem β-lactams 2

Intra-abdominal Infections

• Combination therapy with metronidazole is recommended for polymicrobial infections 1, 4
• Ceftazidime-avibactam plus metronidazole is an effective alternative to carbapenems 4

Urinary Tract Infections

• Aminoglycosides may be considered for uncomplicated UTIs if susceptibility is confirmed 1, 3
• Single-dose aminoglycoside therapy may be effective for simple cystitis 1

Management of Resistant Strains

For Carbapenem-Resistant E. cloacae:

• Ceftazidime-avibactam: First choice for carbapenem-resistant strains that don't produce metallo-β-lactamases 1, 7
• Polymyxin-based combination therapy: Consider for highly resistant strains 1, 8
  • Combination with chloramphenicol has shown synergistic effects against colistin-resistant E. cloacae 8
• Meropenem-vaborbactam or imipenem-cilastatin-relebactam: Newer options for resistant strains 1, 7

Important Clinical Considerations

• First and second-generation cephalosporins should be avoided due to intrinsic resistance 1
• Third-generation cephalosporins (e.g., ceftazidime) are not recommended due to high risk of developing resistance during therapy 1
• E. cloacae can develop resistance during treatment through AmpC β-lactamase induction or derepression 1, 5
• Source control (e.g., drainage of abscesses, removal of infected catheters) is crucial for successful treatment 1
• Duration of therapy typically ranges from 7-14 days depending on infection site, severity, and clinical response 3

Treatment Algorithm

1. Assess infection severity and site
2. Obtain cultures before starting antibiotics when possible
3. Start empiric therapy with a carbapenem for suspected E. cloacae infection
4. Adjust therapy based on susceptibility testing
5. Consider source control measures
6. Monitor clinical response within 48-72 hours
7. De-escalate to narrower spectrum antibiotics if possible to reduce selection pressure for resistance

By following these evidence-based recommendations, clinicians can optimize outcomes for patients with E. cloacae infections while practicing good antimicrobial stewardship.