Treatment of Aerococcus Urinary Tract Infection
For Aerococcus UTI, use amoxicillin or penicillin as first-line therapy, with nitrofurantoin as an alternative for uncomplicated cystitis. 1, 2, 3
First-Line Penicillin Options
Amoxicillin or penicillin are the drugs of choice for Aerococcus urinae UTI based on excellent in vitro susceptibility and clinical experience. 2, 3, 4
- Amoxicillin-clavulanate 20-40 mg/kg per day in 3 divided doses (or standard adult dosing of 500-875mg twice daily) is recommended for oral treatment 5
- Penicillin demonstrates low MICs against Aerococcus urinae with minimal inter-isolate variability 2
- Ampicillin is equally effective if susceptibility is confirmed 6, 4
Alternative Oral Options for Uncomplicated Cystitis
Nitrofurantoin 100mg four times daily achieves clinical and microbiological success in 71%/76% of A. urinae cystitis cases. 7
- Fosfomycin 3g single dose is an alternative option for uncomplicated A. urinae cystitis 1
- Pivmecillinam has demonstrated success in patients with A. urinae cystitis 7
Parenteral Options for Severe or Complicated Infections
For pyelonephritis or complicated UTI, use ceftriaxone 75 mg/kg every 24 hours or cefotaxime 150 mg/kg per day divided every 6-8 hours. 1
- Ciprofloxacin achieved success in patients with pyelonephritis caused by A. urinae 7
- For serious infections (bacteremia, endocarditis), penicillin or ampicillin combined with gentamicin provides rapid bactericidal activity 6, 2
- Penicillin or vancomycin alone exhibit slow or no bactericidal activity; combination with gentamicin is essential for severe cases 2
Treatment Duration
Treat uncomplicated Aerococcus cystitis for 7 days. 1
- For complicated UTI or pyelonephritis, use 7-14 days of therapy 5
- Courses shorter than 7 days are inferior and should be avoided 5
Critical Clinical Considerations
Obtain urine culture with susceptibility testing before initiating treatment, as Aerococcus is frequently misidentified as streptococci or staphylococci on Gram stain. 1, 4
- MALDI-TOF mass spectrometry provides rapid and accurate identification of Aerococcus species 4
- Differentiate between A. urinae and A. sanguinicola, as A. sanguinicola shows lower response rates to nitrofurantoin (42%/50% success) 7
- Elderly men with urinary tract abnormalities, chronic retention, or indwelling catheters are at highest risk 3, 4
Common Pitfalls to Avoid
Do not rely on trimethoprim-sulfamethoxazole or fluoroquinolones as empiric therapy, as their effectiveness against Aerococcus remains uncertain despite in vitro susceptibility. 4
- Avoid treating asymptomatic bacteriuria, which fosters resistance and increases recurrence 1
- Do not misidentify Aerococcus as alpha-hemolytic streptococci or enterococci, leading to inappropriate therapy 4
- Failing to add an aminoglycoside in serious infections (bacteremia, endocarditis) results in inadequate bactericidal activity 6, 2
- Inadequate treatment duration under 7 days leads to treatment failure 1