What antibiotics cover Eikenella infections?

Antibiotics for Eikenella Infections

For Eikenella corrodens infections, the first-line treatment options are amoxicillin-clavulanate, ampicillin-sulbactam, or a third-generation cephalosporin such as ceftriaxone. 1

First-Line Treatment Options

Oral Options:

• Amoxicillin-clavulanate (875/125 mg twice daily)
• Doxycycline (100 mg twice daily) - excellent activity against Eikenella species 1

Intravenous Options:

• Ampicillin-sulbactam (1.5-3.0 g every 6 hours)
• Ceftriaxone (1 g every 12-24 hours)
• Cefotaxime (1-2 g every 6-8 hours)
• Piperacillin-tazobactam (3.37-4.5 g every 6-8 hours)

Treatment Algorithm

1. Determine infection severity:

   • For mild-moderate infections: Use oral therapy
   • For severe infections: Begin with IV therapy

2. Consider infection location:

   • For human bite wounds (common source of Eikenella): Use amoxicillin-clavulanate or ampicillin-sulbactam as these cover the polymicrobial nature of these infections 1
   • For endocarditis involving HACEK organisms (including Eikenella): Use ceftriaxone for 4 weeks 1

3. Consider patient factors:

   • For penicillin allergy: Use doxycycline or a fluoroquinolone (e.g., ciprofloxacin) 1
   • For immunocompromised patients: Consider broader coverage with piperacillin-tazobactam

Important Considerations

Antibiotic Resistance Patterns

Eikenella corrodens has important resistance patterns to be aware of:

• Resistant to: Clindamycin, macrolides, aminoglycosides, metronidazole, and first-generation cephalosporins 1, 2, 3
• Susceptible to: Penicillins, tetracyclines, third-generation cephalosporins, and fluoroquinolones 2, 4, 5

Common Pitfalls

• Misdiagnosis: Eikenella grows slowly and requires special culture conditions (CO2 enrichment). Alert the laboratory when Eikenella is suspected to ensure proper isolation techniques 2
• Inadequate coverage: Using clindamycin or metronidazole alone for human bite wounds can lead to treatment failure and persistent Eikenella infection 2, 3
• Insufficient duration: Eikenella infections often require longer treatment courses, especially in cases of endocarditis (4 weeks) 1

Mixed Infections

Eikenella is frequently part of polymicrobial infections, particularly with streptococci. Treatment should cover both organisms:

• Beta-lactam/beta-lactamase inhibitor combinations (amoxicillin-clavulanate, ampicillin-sulbactam) provide excellent coverage for mixed infections 1
• For human bite wounds, empiric therapy should always cover both Eikenella and other oral flora 1

Duration of Therapy

• Soft tissue infections: 7-10 days
• Endocarditis: 4 weeks of ceftriaxone or ampicillin plus gentamicin 1
• Bone/joint infections: 4-6 weeks

Remember that surgical drainage is often necessary for abscesses containing Eikenella, as antibiotics alone may be insufficient for adequate treatment 4, 3.