What is the recommended antibiotic (abx) treatment for Aerococcus sanguinicola infections?

Antibiotic Treatment for Aerococcus sanguinicola Infections

Penicillin is the recommended first-line antibiotic for Aerococcus sanguinicola infections, with consideration for adding an aminoglycoside (gentamicin) in severe invasive infections such as infective endocarditis. 1, 2, 3

First-Line Treatment

• Penicillin G is the reference antibiotic for A. sanguinicola infections, as all tested isolates demonstrate universal susceptibility 1, 3
• Alternative beta-lactams with proven efficacy include:
  • Ampicillin 3
  • Cefotaxime 1
  • Ceftriaxone 4
  • Meropenem 1

Severe/Invasive Infections

For infective endocarditis or bacteremia with severe sepsis:

• Penicillin plus gentamicin combination therapy should be considered, as synergy between these agents has been demonstrated in approximately 50% of A. sanguinicola isolates 2, 5
• This combination is particularly important in endocarditis cases, where aminoglycoside addition may improve outcomes despite variable synergy testing results 2, 5

Alternative Agents

When beta-lactams cannot be used:

• Vancomycin - all isolates show universal susceptibility 1, 3, 4
• Linezolid - demonstrates complete susceptibility across tested isolates 1
• Rifampicin - shows universal susceptibility and may be considered as adjunctive therapy 1, 3

Important Clinical Considerations

Urinary Tract Focus

• The urinary tract is the primary source in most A. sanguinicola infections, particularly in elderly patients with underlying urological abnormalities 3, 5
• Evaluate and address any urinary tract pathology as part of source control 5

Problematic Agents

• Avoid trimethoprim-sulfamethoxazole and fluoroquinolones as first-line agents, as their efficacy against aerococci remains uncertain and unreliable 2
• These agents should not be used for definitive therapy even if in vitro testing suggests susceptibility 2

Duration of Therapy

• Uncomplicated bacteremia: 10-14 days of intravenous therapy 3
• Infective endocarditis: Extended courses following standard endocarditis treatment protocols, typically 4-6 weeks with combination therapy 2, 5
• Urinary tract infections: Standard UTI treatment durations, though specific data for aerococci are limited 4

Prognosis

• Despite affecting elderly patients with significant comorbidities, the prognosis of A. sanguinicola bacteremia without endocarditis is relatively favorable when appropriately treated 2, 5
• Mortality risk increases with delayed recognition or inadequate treatment, particularly in endocarditis cases 3, 5

Identification Pitfall

• A. sanguinicola is frequently misidentified as streptococci or staphylococci on conventional testing, leading to potential treatment delays 2
• MALDI-TOF mass spectrometry provides rapid and accurate species identification 2, 4