Is Staphylococcus (S.) epidermidis a potential urinary tract infection (UTI) pathogen and what antibiotics can be used to treat it?

From the Guidelines

Staphylococcus epidermidis is considered a potential urinary tract infection (UTI) pathogen, although it is less common than other bacteria. When it comes to treating S. epidermidis UTIs, the choice of antibiotics is crucial. According to the European Association of Urology guidelines on urological infections, published in 2024 1, the recommendations for treating complicated UTIs include using a combination of antibiotics such as amoxicillin plus an aminoglycoside or a second-generation cephalosporin plus an aminoglycoside. However, for S. epidermidis specifically, which is often methicillin-resistant, alternative antibiotics may be necessary. Some possible options include:

• Vancomycin 15-20 mg/kg IV every 12 hours
• Linezolid 600 mg twice daily
• Daptomycin 4-6 mg/kg IV every 24 hours
• Trimethoprim-sulfamethoxazole (Bactrim) at 160/800 mg twice daily for 7-14 days
• Nitrofurantoin (Macrobid) 100 mg twice daily for 7 days, although its effectiveness against S. epidermidis can vary. It's essential to note that antibiotic susceptibility testing is crucial for guiding treatment, as resistance patterns vary widely. Patients should complete the full course of antibiotics even if symptoms improve quickly, drink plenty of fluids to help flush bacteria from the urinary tract, and seek medical attention if symptoms worsen or don't improve within 48 hours of starting treatment. Key considerations in treating S. epidermidis UTIs include:
• The potential for biofilm production, which can make treatment more challenging
• The need for effective antibiotic penetration into the urinary tract
• The importance of addressing any underlying urological abnormalities or complicating factors, as recommended by the European Association of Urology guidelines 1.

From the Research

Staphylococcus Epidermidis as a UTI Pathogen

• Staphylococcus epidermidis is considered a potential urinary tract infection (UTI) pathogen, particularly in children with anatomic variants or a history of instrumentation 2, 3, 4.
• It can also cause UTIs in adults, especially those with underlying medical conditions such as nephrolithiasis 5.
• Historically, S. epidermidis was considered a contaminant when grown on urine cultures, but a growing body of literature suggests that it can be a causative agent of UTIs 2, 3, 4.

Antibiotic Treatment for S. Epidermidis UTIs

• The treatment for S. epidermidis UTIs typically involves the use of antibiotics, such as trimethoprim-sulfamethoxazole 6.
• Intravenous antibiotics may be necessary in severe cases, such as pyelonephritis with bacteremia 5.
• The choice of antibiotic should be guided by susceptibility testing and clinical judgment, as S. epidermidis can exhibit resistance to various antibiotics.

Clinical Considerations

• Clinicians should consider the possibility of S. epidermidis as a causative agent of UTIs, especially in patients with underlying medical conditions or anatomic abnormalities 2, 5, 3, 4.
• Urine cultures should be carefully evaluated, and S. epidermidis should not be automatically dismissed as a contaminant 2, 3, 4.
• Further workup for urinary tract abnormalities may be indicated in cases of S. epidermidis UTIs, especially in children 4.