What are the recommended antibiotic treatments for Enterobacter infections?

Antibiotic Recommendations for Enterobacter Infections

For infections caused by Enterobacter bacteria, carbapenems (meropenem or imipenem) are strongly recommended as first-line treatment for severe infections and bacteremia. 1

First-Line Treatment Options

For Severe Infections/Bacteremia:

• Carbapenems:
  • Meropenem: 1g IV every 8 hours (adjust for renal function) 1
  • Imipenem: 500mg IV every 6 hours 1
  • Ertapenem: Can be used for bloodstream infections without septic shock 2

For KPC-producing Carbapenem-resistant Enterobacter:

• Novel β-lactam/β-lactamase inhibitor combinations:
  • Ceftazidime-avibactam: 2.5g (2g ceftazidime + 0.5g avibactam) IV every 8 hours 2, 1
  • Meropenem-vaborbactam: Highly effective against KPC-producing strains 2, 3

For OXA-48-like Producing Carbapenem-resistant Enterobacter:

• Ceftazidime-avibactam should be the first-line treatment option 2

For Metallo-β-lactamase (MBL) Producing Carbapenem-resistant Enterobacter:

• Ceftazidime-avibactam plus aztreonam is strongly recommended 2
• Cefiderocol may also be considered as an alternative 2, 4

Treatment for Less Severe Infections

For non-severe, low-risk infections due to third-generation cephalosporin-resistant Enterobacter:

• Piperacillin-tazobactam
• Fluoroquinolones (if susceptible)
• Aminoglycosides (particularly for urinary tract infections) 2

For complicated urinary tract infections without septic shock:

• Aminoglycosides (when active in vitro) for short durations of therapy
• IV fosfomycin 2

Combination Therapy Considerations

• For polymicrobial infections: Add metronidazole to cover anaerobes 1
• For carbapenem-resistant Enterobacter infections susceptible to and treated with ceftazidime-avibactam, meropenem-vaborbactam, or cefiderocol, combination therapy is not recommended 2
• For severe infections caused by carbapenem-resistant Enterobacter susceptible only to polymyxins, aminoglycosides, tigecycline, or fosfomycin, treatment with more than one drug active in vitro is suggested 2

Important Caveats and Pitfalls

1. Avoid first and second-generation cephalosporins due to intrinsic resistance 1

2. Avoid third-generation cephalosporins (e.g., ceftazidime alone) due to high risk of developing resistance during therapy 1

3. Avoid cephamycins and cefepime for third-generation cephalosporin-resistant Enterobacter infections 2

4. Avoid tigecycline for bloodstream infections and hospital-acquired/ventilator-associated pneumonia 2

5. Source control is crucial - drainage of abscesses, removal of infected catheters, etc. 1

6. Consider local resistance patterns when selecting empiric therapy

7. De-escalate to narrower spectrum antibiotics once patients are stabilized and susceptibility results are available 2

8. Monitor for resistance development during therapy, particularly with Enterobacter species which can rapidly develop resistance

The choice of antibiotic should be guided by susceptibility testing whenever possible, with carbapenems remaining the cornerstone of therapy for severe Enterobacter infections. For carbapenem-resistant strains, the specific mechanism of resistance (KPC, MBL, OXA-48) should determine the optimal treatment approach.