Treatment of Aerococcus sanguinicola with Augmentin
Augmentin (amoxicillin-clavulanate) is an appropriate and effective treatment option for Aerococcus sanguinicola urinary tract infection with >100,000 cfu/mL, as this organism demonstrates universal susceptibility to beta-lactam antibiotics including ampicillin and amoxicillin. 1, 2
Antimicrobial Susceptibility Evidence
A. sanguinicola shows excellent susceptibility to beta-lactam antibiotics:
- 100% susceptibility to ampicillin and penicillin has been documented across multiple studies of clinical isolates 1, 2
- All A. sanguinicola isolates tested (n=18) demonstrated 100% susceptibility to benzylpenicillin and ampicillin using EUCAST methodology 1
- A larger study of 120 Aerococcus isolates (both A. urinae and A. sanguinicola) found universal susceptibility to penicillin, cefotaxime, meropenem, vancomycin, linezolid, and rifampicin 2
- Clinical case series confirm susceptibility to ampicillin, cefuroxime, and penicillin 3
Important Distinction: A. sanguinicola vs A. urinae
A. sanguinicola differs significantly from A. urinae in its resistance to certain oral agents:
- Ciprofloxacin resistance occurs in approximately 11% of Aerococcus species, making fluoroquinolones less reliable 1
- Nitroxoline shows poor activity against A. sanguinicola (MIC50/90 64/128 mg/L) compared to excellent activity against A. urinae, and should be avoided for A. sanguinicola 1
- Nitrofurantoin achieved only 42% clinical success and 50% microbiological success in A. sanguinicola UTI, compared to 71%/76% for A. urinae 4
Clinical Context and Severity
The bacterial load of >100,000 cfu/mL indicates significant bacteriuria requiring treatment:
- This colony count meets standard criteria for urinary tract infection 5
- A. sanguinicola can progress from UTI to urosepsis if untreated, particularly in elderly patients 6
- The median age of patients with A. sanguinicola infection is 82 years, with infections ranging from simple UTI to urosepsis and endocarditis 6, 3
Recommended Treatment Approach
For A. sanguinicola UTI with >100,000 cfu/mL:
- Augmentin (amoxicillin-clavulanate) 875/125 mg twice daily is appropriate based on universal susceptibility to ampicillin 7, 1
- Alternative beta-lactam options include ampicillin, penicillin, or ceftriaxone, all showing 100% susceptibility 1, 2
- Avoid nitrofurantoin as monotherapy given the 50-58% failure rate in A. sanguinicola 4
- Exercise caution with ciprofloxacin due to 11% resistance rates 1
Treatment Duration
Standard UTI treatment duration should be applied:
- For uncomplicated cystitis: 5-7 days of therapy 7
- For complicated UTI or pyelonephritis: 10-14 days 7
- Monitor for progression to bacteremia or endocarditis, particularly in elderly patients with underlying conditions 6, 3
Common Pitfalls to Avoid
- Do not assume A. sanguinicola behaves like A. urinae regarding nitrofurantoin susceptibility 1, 4
- Do not rely on ciprofloxacin without susceptibility testing due to documented resistance 1
- Do not undertreated based on age alone - elderly patients are at highest risk for progression to serious infection 6, 3