What is the treatment for a urinary tract infection (UTI) caused by Staphylococcus?

Treatment of Staphylococcal Urinary Tract Infection

For staphylococcal UTI, obtain a urine culture before initiating treatment, then use culture-directed antimicrobial therapy based on susceptibility testing for 7-14 days, recognizing that coagulase-negative staphylococci are typically contaminants while Staphylococcus aureus represents true infection requiring treatment. 1

Key Diagnostic Considerations

Distinguish between pathogenic and contaminant staphylococci:

• Coagulase-negative staphylococci (including S. epidermidis) and Corynebacterium species are NOT considered clinically relevant urine isolates in otherwise healthy patients 1
• S. saprophyticus is a recognized uropathogen causing >10% of uncomplicated UTIs in young women 2
• S. aureus bacteriuria is a true pathogen, particularly in catheterized patients, and warrants treatment 3

Pre-Treatment Requirements

Always obtain urine culture before starting antibiotics:

• Culture is mandatory to document true UTI and guide antimicrobial management 1
• For catheterized patients with catheters in place ≥2 weeks, replace the catheter and obtain culture from the fresh catheter before initiating therapy 1
• Antimicrobial sensitivities should be used to adjust initial empiric therapy 1

Treatment Approach

Empiric Therapy Selection

Base initial antibiotic choice on:

• Local antimicrobial sensitivity patterns and antibiograms 1
• Patient-specific factors including allergies, prior culture data, and recent antibiotic exposure 1
• Severity of illness and ability to tolerate oral medications 1

For complicated UTI with systemic symptoms, use combination therapy: 1

• Amoxicillin plus aminoglycoside, OR
• Second-generation cephalosporin plus aminoglycoside, OR
• Intravenous third-generation cephalosporin

Specific Staphylococcal Considerations

For confirmed S. aureus UTI:

• Methicillin-resistant S. aureus (MRSA) comprises 86% of S. aureus urinary isolates in long-term care settings 3
• If MRSA is suspected or confirmed, follow IDSA MRSA treatment guidelines 1
• Trimethoprim-sulfamethoxazole has documented efficacy for staphylococcal UTI 4

For S. saprophyticus (young women with uncomplicated UTI):

• First-line agents: nitrofurantoin, trimethoprim-sulfamethoxazole, or fosfomycin 1
• Treatment duration: 3-7 days for uncomplicated cases 1

Treatment Duration

Standard duration is 7-14 days: 1

• 7 days for patients with prompt symptom resolution 1
• 10-14 days for delayed response or when prostatitis cannot be excluded in men 1
• Shorter courses (7 days) may be considered when patient is hemodynamically stable and afebrile for ≥48 hours 1

Special Populations

Catheter-Associated Staphylococcal UTI

Management requires:

• Remove or replace indwelling catheter if present ≥2 weeks to hasten symptom resolution 1
• 33% of catheterized patients with S. aureus bacteriuria have symptomatic UTI, and 13% are bacteremic at presentation 3
• 58% of patients have persistent staphylococcal bacteriuria at ≥2 months, with median duration of 4.3 months 3

Pediatric Patients (2-24 months)

Treatment considerations:

• Oral or parenteral routes are equally efficacious 1
• Duration: 7-14 days 1
• Coagulase-negative staphylococci are NOT considered clinically relevant isolates in otherwise healthy children 1

Critical Pitfalls to Avoid

Do not treat asymptomatic bacteriuria:

• Treatment of asymptomatic bacteriuria fosters antimicrobial resistance and increases recurrent UTI risk 1
• Exception: pregnant women and patients undergoing invasive urinary procedures 1

Avoid fluoroquinolones for empiric therapy if:

• Local resistance rate is ≥10% 1
• Patient is from urology department or used fluoroquinolones in last 6 months 1

Recognize S. aureus as a serious pathogen:

• S. aureus bacteriuria can lead to subsequent invasive infection, with late-onset bacteremia occurring up to 12 months after initial isolation 3
• Persistent staphylococcal bacteriuria may require consideration of underlying urological abnormalities 5, 6

Monitoring and Follow-Up

Adjust therapy based on culture results:

• Tailor antibiotics according to susceptibility testing once available 1
• If symptoms persist despite treatment, repeat urine culture to assess for ongoing bacteriuria before prescribing additional antibiotics 1
• For recurrent infections with same organism at close intervals, investigate for bacterial focus or structural abnormality requiring correction 6