What is the treatment for a patient with a catheter-associated urinary tract infection (CAUTI) with urine culture showing >100,000 colony-forming units (CFU) of Enterococcus faecalis and >100,000 CFU of Staphylococcus aureus from an indwelling Foley catheter?

Management of Polymicrobial CAUTI with Enterococcus faecalis and Staphylococcus aureus

Replace the Foley catheter immediately if it has been in place for ≥2 weeks, obtain urine culture from the fresh catheter, and initiate empirical broad-spectrum antibiotics covering both Gram-positive organisms while awaiting susceptibility results. 1, 2

Immediate Management Steps

Catheter Management

• Replace the indwelling catheter before starting antibiotics if it has been in place for ≥2 weeks, as this hastens symptom resolution and reduces risk of subsequent infection by removing the biofilm-laden device 1, 2
• Obtain the urine culture specimen from the freshly placed catheter prior to initiating therapy, as the catheter biofilm may harbor organisms not accurately reflected in cultures from the old catheter 3
• Remove the catheter entirely as soon as it is no longer clinically needed, as catheterization duration is the most important risk factor for CAUTI development 1, 2

Culture and Diagnostic Considerations

• Obtain urine culture before initiating antimicrobial therapy due to the high likelihood of antimicrobial resistance in CAUTI 1, 2, 3
• The polymicrobial nature of this infection (Enterococcus faecalis and Staphylococcus aureus) is common in CAUTI, with both organisms frequently isolated from catheter-associated infections 4, 5
• Assess for biofilm formation, as both organisms are significant biofilm producers in CAUTI, which increases antimicrobial resistance 4, 6

Empirical Antibiotic Selection

First-Line Empirical Regimens

For patients requiring parenteral therapy:

• Intravenous third-generation cephalosporin (e.g., ceftriaxone) PLUS vancomycin to cover both Enterococcus faecalis and potential methicillin-resistant Staphylococcus aureus (MRSA), as multi-drug resistance is significantly higher in CAUTI 2, 4
• Alternative: Ampicillin/sulbactam provides coverage for both organisms and is recommended by European guidelines for complicated UTIs 2

For patients with mild-moderate symptoms who can tolerate oral therapy:

• Amoxicillin-clavulanate may provide adequate coverage for susceptible strains of both organisms, though this should be considered only after susceptibility confirmation 1, 2

Critical Considerations for Antibiotic Selection

• Do NOT use fluoroquinolones (including levofloxacin) as monotherapy for this polymicrobial infection, as they provide inadequate coverage for Enterococcus species 1, 3
• Do NOT use nitrofurantoin for CAUTI, as it doesn't achieve adequate serum concentrations to treat potential systemic infection 1
• Base empirical therapy on local antimicrobial resistance patterns, as CAUTI organisms have higher resistance rates than community-acquired UTI pathogens 1, 2, 4

Tailored Therapy Based on Susceptibilities

Adjusting Treatment

• Narrow antibiotic spectrum once susceptibility results are available to target the specific organisms and their resistance patterns 1, 2
• For Enterococcus faecalis, susceptibility to ampicillin, vancomycin, linezolid, and tigecycline should be assessed 5
• For Staphylococcus aureus, determine methicillin susceptibility (MRSA vs MSSA), as MRSA rates are significantly higher in CAUTI than community infections 4
• If both organisms are susceptible, ampicillin or amoxicillin-clavulanate may be appropriate for step-down oral therapy 2, 5

Treatment Duration

Standard Duration

• 7 days of treatment if symptoms resolve promptly, regardless of whether the catheter remains in place 1, 2, 3
• 10-14 days for patients with delayed clinical response or if systemic symptoms are present 1, 2, 3

Extended Duration Considerations

• Consider 14 days of treatment for male patients when prostatitis cannot be excluded 2
• If the patient does not show clinical improvement with defervescence by 72 hours, extend treatment and perform urologic evaluation 1

Common Pitfalls to Avoid

Critical Errors

• Do NOT treat asymptomatic bacteriuria in catheterized patients, as this leads to antimicrobial resistance without clinical benefit 7, 1
• Do NOT delay catheter replacement if it has been in place for ≥2 weeks, as biofilm formation on the catheter protects organisms from antimicrobials 7, 1
• Do NOT use prophylactic antimicrobials at the time of catheter placement, removal, or routine replacement 7

Resistance Considerations

• Be aware that biofilm-forming organisms (both Enterococcus and Staphylococcus are significant biofilm producers) demonstrate significantly higher antimicrobial resistance than non-biofilm formers 4, 6
• Multi-drug resistance, MRSA, and vancomycin-resistant Enterococci (VRE) are significantly more common in CAUTI than community-acquired UTI 4, 5
• The polymicrobial nature of this infection increases the complexity of treatment and the likelihood of resistance 8, 4