What is the recommended treatment for Corynebacterium aurimucosum infections?

Treatment of Corynebacterium aurimucosum Infections

For Corynebacterium aurimucosum infections, amoxicillin is the first-line treatment of choice, with vancomycin or linezolid as alternatives for severe infections or in cases of beta-lactam allergy. 1

Antimicrobial Susceptibility Profile

C. aurimucosum has a specific susceptibility pattern that should guide treatment decisions:

• Highly effective agents (>80% susceptibility):

  • Amoxicillin (MIC90: 2 μg/ml)
  • Vancomycin (100% susceptible)
  • Linezolid (100% susceptible)
  • Gentamicin
  • Tetracycline
  • Rifampicin

• Limited activity (~50% susceptibility):

  • Cefotaxime
  • Ciprofloxacin (shows bimodal resistance pattern)

• Poor activity (<10% susceptibility):

  • Penicillin G
  • Clindamycin

Treatment Algorithm

1. Non-severe infections (UTIs, mild skin/soft tissue infections)

• First-line: Amoxicillin
• Alternatives if allergic to beta-lactams:
  • Tetracycline
  • Gentamicin (for UTIs)

2. Severe infections (bacteremia, bone/joint infections, severe tissue infections)

• First-line options:
  • Vancomycin
  • Linezolid
  • Amoxicillin (if susceptible and patient is stable)

3. Mixed infections (common in bone/joint infections)

• Consider broader coverage based on suspected co-pathogens
• Ensure coverage for C. aurimucosum with one of the agents above

Special Considerations

Bone and Joint Infections

These represent approximately 50% of confirmed C. aurimucosum infections 1. For these cases:

• Vancomycin or linezolid should be preferred initially
• Consider surgical debridement in addition to antimicrobial therapy
• Longer treatment courses (4-6 weeks) are typically required

Urinary Tract Infections

These represent about 21% of confirmed infections 1:

• Amoxicillin is typically sufficient if susceptible
• Gentamicin can be considered as an alternative

Bacteremia (14% of infections)

• Vancomycin or linezolid should be used initially
• De-escalate to amoxicillin if susceptible and patient is clinically improving

Treatment Duration

• Uncomplicated UTIs: 5-7 days
• Bacteremia: 10-14 days
• Bone and joint infections: 4-6 weeks

Important Pitfalls to Avoid

1. Misidentification: C. aurimucosum can be misidentified by conventional methods. MALDI-TOF mass spectrometry or gene sequencing should be used for accurate identification.

2. Dismissing as contaminant: While corynebacteria are often considered contaminants, C. aurimucosum is an opportunistic pathogen that can cause serious infections, particularly in immunocompromised patients.

3. Inappropriate empiric therapy: Avoid fluoroquinolones and clindamycin as empiric therapy due to high resistance rates.

4. Inadequate treatment duration: Particularly for bone and joint infections, ensure adequate duration of therapy to prevent relapse.

5. Overlooking mixed infections: C. aurimucosum often occurs in polymicrobial infections, particularly in bone/joint and skin/soft tissue infections. Ensure adequate coverage for all isolated pathogens.

The evidence for C. aurimucosum treatment is limited, but based on in vitro susceptibility data and clinical experience, amoxicillin, vancomycin, and linezolid represent the most reliable therapeutic options for this emerging pathogen 1, 2.