What is the recommended treatment for a patient with dysuria and a positive urine culture for Staphylococcus (Staph) aureus?

Treatment of Dysuria with Staphylococcus aureus in Urine

For symptomatic urinary tract infection with confirmed S. aureus (≥50,000 CFU/mL as a single pathogen), treat with targeted antimicrobial therapy based on susceptibility testing: cefazolin or antistaphylococcal penicillins for MSSA, or vancomycin/daptomycin for MRSA, for 7-14 days depending on clinical response. 1

Initial Assessment: Distinguish True Infection from Colonization

• Obtain a properly collected urine culture to confirm S. aureus as the causative pathogen with ≥50,000 CFU/mL as a single organism 1
• Verify the patient is truly symptomatic with dysuria, frequency, urgency, or suprapubic pain—asymptomatic bacteriuria should NOT be treated in most patients as it typically represents contamination or colonization 2, 1
• Assess for risk factors including urinary catheterization, recent urological procedures, male sex, diabetes, or structural urinary abnormalities 3, 4
• Consider S. aureus bacteremia as a potential source, particularly if the patient has persistent fever, appears systemically ill, has had recent urological instrumentation, or has risk factors for endovascular infection 1, 4, 5

Critical Decision Point: Blood Cultures

• Obtain blood cultures in high-risk patients including those with persistent fever, systemic symptoms, urological instrumentation, indwelling catheters, or implanted devices 1, 4, 5
• Do NOT routinely obtain blood cultures in well-appearing outpatients with isolated dysuria and no risk factors 4
• If S. aureus bacteremia is confirmed, perform transesophageal echocardiography for high-risk patients (persistent bacteremia ≥48 hours, persistent fever, metastatic infection foci, or implantable cardiac devices) 1, 5

Antimicrobial Treatment for Symptomatic UTI

For Methicillin-Susceptible S. aureus (MSSA):

• First-line: Cefazolin or antistaphylococcal penicillins (nafcillin, oxacillin) based on susceptibility testing 1, 5
• Alternative if penicillin allergy: Ciprofloxacin or clindamycin 1
• Trimethoprim-sulfamethoxazole may be effective based on susceptibility (91% susceptibility in community-acquired cases) 3

For Methicillin-Resistant S. aureus (MRSA):

• First-line: Vancomycin or daptomycin based on susceptibility testing 2, 1, 5
• Alternative options: Linezolid (600 mg PO/IV twice daily) 2
• Vancomycin trough concentrations of 15-20 mcg/mL are recommended for serious infections, though routine monitoring is not required for uncomplicated UTI in patients with normal renal function 2

Treatment Duration:

• 7 days for prompt symptom resolution 1
• 10-14 days for delayed response or complicated infection 1, 6
• Minimum 14 days if S. aureus bacteremia is confirmed and uncomplicated 1, 5
• 4-6 weeks if complicated bacteremia or endocarditis is present 1, 5

Special Considerations for Catheter-Associated Bacteriuria

• Replace the catheter if it has been in place ≥2 weeks before starting antimicrobial therapy, as antibiotic therapy alone will likely fail due to biofilm formation 1
• Remove short-term catheters when feasible to improve treatment success 2
• Consider catheter removal in patients with persistent symptoms despite appropriate antibiotics 1

Monitoring and Follow-Up

• Assess clinical response within 48-72 hours and adjust antibiotics based on culture and susceptibility results 1
• Obtain repeat urine culture in patients with urinary catheterization, urological abnormalities, diabetes, or inpatient status, as these factors are associated with recurrence 4
• Do NOT routinely repeat urine cultures in well-appearing outpatients who respond clinically 4

Common Pitfalls to Avoid

• Do not treat asymptomatic bacteriuria except before endoscopic urologic procedures with mucosal trauma (use 1-2 doses of targeted antimicrobial 30-60 minutes pre-procedure) 2, 1
• Do not assume contamination in male patients or those with risk factors—S. aureus bacteriuria warrants investigation 6, 4
• Do not miss occult bacteremia—S. aureus in urine may represent bacteremic seeding from another site, particularly in patients with recent procedures or indwelling devices 4, 5
• Do not use empiric fluoroquinolones if local resistance rates are >10% or if the patient has used fluoroquinolones in the last 6 months 6, 7
• Do not use vancomycin for MSSA when susceptibility results are available—beta-lactams are superior 2, 5