What are the recommended antibiotic choices for Eikenella corrodens infections?

Antibiotic Treatment for Eikenella corrodens Infections

Ceftriaxone is the first-line antibiotic treatment for Eikenella corrodens infections, administered at 2g IV/IM once daily for 4 weeks in native valve endocarditis and 6 weeks in prosthetic valve endocarditis. 1, 2

First-Line Treatment Options

• Ceftriaxone: 2g IV/IM once daily 1, 2

  • Preferred treatment due to high efficacy against HACEK organisms
  • Duration: 4 weeks for native valve infections, 6 weeks for prosthetic material

• Other third/fourth-generation cephalosporins may be substituted 1

  • Examples include cefotaxime
  • Similar dosing and duration as ceftriaxone

Alternative Treatment Options

For patients unable to tolerate cephalosporins:

• Ampicillin: 2g IV every 4 hours 1, 2

  • Only if susceptibility testing confirms sensitivity
  • Many E. corrodens strains now produce β-lactamase

• Fluoroquinolones: 1

  • Ciprofloxacin: 1000 mg/day orally or 800 mg/day IV in 2 divided doses
  • Levofloxacin or moxifloxacin may be substituted
  • Limited clinical evidence but good in vitro activity

• Ampicillin-sulbactam: 1.5-3g IV every 6-8 hours 2, 3

  • Effective against β-lactamase-producing strains
  • Resistance has been reported in some cases

Important Clinical Considerations

1. Resistance patterns:

   • E. corrodens is uniformly resistant to clindamycin and metronidazole 4, 5
   • Increasing prevalence of β-lactamase-producing strains 1
   • Poor activity of aminoglycosides (gentamicin, amikacin) 6

2. Mixed infections:

   • E. corrodens often occurs with other organisms, particularly streptococci 4, 3
   • Treatment with antibiotics that don't cover E. corrodens can lead to persistent pure E. corrodens infection 4

3. Special situations:

   • For human bite wounds: Amoxicillin-clavulanate is preferred empiric therapy 2, 7
   • For intra-abdominal infections: Ampicillin, penicillin, or second-generation cephalosporins 3

4. Treatment duration:

   • Endocarditis: 4 weeks for native valve, 6 weeks for prosthetic valve 1, 2
   • Soft tissue infections: 7-14 days depending on severity 2
   • Persistent or recurrent infections may require longer treatment courses 5

Pitfalls to Avoid

1. Laboratory considerations:

   • Alert laboratory when E. corrodens is suspected due to slow growth and special requirements 4
   • Susceptibility testing is essential due to variable resistance patterns

2. Treatment failures:

   • Using clindamycin or metronidazole alone (E. corrodens is resistant)
   • Using penicillin without confirming β-lactamase status
   • Inadequate surgical drainage of abscesses (often required alongside antibiotics) 5, 7

3. Clinical course:

   • Infections may appear indolent and evolve slowly 3
   • Persistent symptoms despite weeks of seemingly appropriate therapy should raise suspicion for E. corrodens 5

For optimal outcomes, combine appropriate antibiotic therapy with adequate surgical drainage when abscesses are present.