Treatment of UTI Caused by Aerococcus urinae in a Patient on Anticoagulants
For patients on anticoagulants with a urinary tract infection caused by Aerococcus urinae, nitrofurantoin is the recommended first-line treatment due to its documented clinical and microbiological success rates of 71-76% against this pathogen.
First-Line Treatment Options
- Nitrofurantoin 100 mg orally every 6 hours is the preferred treatment for uncomplicated UTI caused by Aerococcus urinae in patients on anticoagulants, as it has demonstrated good clinical efficacy against this organism 1
- For patients with normal renal function, a 5-day course of nitrofurantoin is recommended for uncomplicated lower UTI 2, 3
- Nitrofurantoin is contraindicated if creatinine clearance is <60 mL/min due to inadequate urinary concentrations and increased toxicity risk 4
Alternative Treatment Options
- Fosfomycin 3 g as a single oral dose is an effective alternative for patients who cannot tolerate nitrofurantoin or have renal impairment 2, 3
- Pivmecillinam has shown success in treating A. urinae cystitis and can be considered as an alternative option 1
- Penicillins (ampicillin/amoxicillin) are highly effective against A. urinae with 100% susceptibility in vitro and can be used if other options are unavailable 5, 6
- Ciprofloxacin should be reserved for cases of pyelonephritis, as approximately 10.9% of A. urinae isolates show resistance to fluoroquinolones 1, 6
Special Considerations for Anticoagulated Patients
- When treating UTI in anticoagulated patients, avoid antibiotics that may interact with anticoagulants or increase bleeding risk 2
- Single-dose fosfomycin may be particularly advantageous in anticoagulated patients as it minimizes potential drug interactions due to its short duration of therapy 2
- Monitor anticoagulation parameters more frequently during antibiotic treatment, especially with antibiotics known to interact with anticoagulants 2
Treatment Duration and Follow-up
For uncomplicated lower UTI, treatment duration should be:
For complicated UTI or pyelonephritis, extend treatment to 7-14 days based on clinical response 2, 1
Obtain a urine culture before starting antibiotics to guide therapy if symptoms don't resolve 4
Consider follow-up urine culture after treatment completion to confirm microbiological cure, especially in patients with recurrent infections 4
Important Caveats
- A. urinae infections are more common in elderly patients with underlying urological conditions and may require longer treatment courses in these populations 5
- If the patient has signs of systemic infection (fever, flank pain), consider parenteral therapy with ampicillin or a cephalosporin 6, 7
- In cases of severe infection or bacteremia, longer treatment courses (4 weeks or more) may be necessary 7
- Nitroxoline shows high activity against A. urinae in vitro (97.6% susceptibility) and could be considered as an alternative oral treatment option where available 6