Would you treat a patient with Enterococcus faecalis in urine with a colony count of 50,000-100,000 Colony-Forming Units per Milliliter (CFU/mL)?

Treatment of Enterococcus faecalis in Urine with Colony Count 50,000-100,000 CFU/mL

Treatment is recommended for Enterococcus faecalis in urine with colony counts of 50,000-100,000 CFU/mL when accompanied by urinary symptoms or pyuria, as this represents a clinically significant urinary tract infection requiring antimicrobial therapy. 1, 2

Diagnostic Considerations

When evaluating Enterococcus faecalis with colony counts of 50,000-100,000 CFU/mL, consider:

• Presence of symptoms: Dysuria, frequency, urgency, and suprapubic pain strongly suggest a true UTI requiring treatment 2
• Pyuria: Significant pyuria (≥10 WBC/mm³ on enhanced urinalysis or ≥5 WBC per high power field on centrifuged specimen) indicates infection 1
• Patient factors: Hospitalized patients and those with symptoms are significantly more likely to have true UTI even with colony counts below 100,000 CFU/mL 3

Treatment Algorithm

1. If symptomatic OR pyuria present: Treat as active infection

   • First-line options:
     • Ampicillin 500mg orally four times daily for 5-7 days 1, 2
     • Nitrofurantoin 100mg twice daily for 5 days 2
     • Fosfomycin 3g single oral dose 2

2. If asymptomatic AND no pyuria: Do not treat

   • Asymptomatic bacteriuria should not be treated to avoid antimicrobial resistance and disruption of protective flora 1, 2

Special Considerations

• Underlying conditions: Consider structural abnormalities if Enterococcus faecalis is isolated, as studies show higher rates of urological abnormalities in enterococcal UTIs 4
• Risk of endocarditis: E. faecalis can cause endocarditis, but this is rare with uncomplicated UTIs without risk factors 1
• Recurrent infections: If recurrent enterococcal UTIs occur, evaluate for anatomical abnormalities, stones, or other underlying conditions 2

Evidence Strength and Rationale

The American Academy of Pediatrics guidelines specifically state that 50,000 CFU/mL is the appropriate threshold for specimens obtained by catheterization to diagnose UTI 1. For clean-catch specimens, colony counts of 50,000-100,000 CFU/mL are clinically significant when accompanied by symptoms or pyuria 2, 3.

Recent research demonstrates that more than half of patients with enterococcal counts below 100,000 CFU/mL may have true UTI, particularly if hospitalized or symptomatic 3. This contradicts older approaches that only considered counts ≥100,000 CFU/mL as significant.

Common Pitfalls to Avoid

• Undertreating: Failing to treat symptomatic patients with counts of 50,000-100,000 CFU/mL can lead to persistent infection and complications 3
• Overtreating: Treating asymptomatic bacteriuria increases antimicrobial resistance and may eliminate protective flora 1, 2
• Inadequate follow-up: Not obtaining repeat cultures when symptoms persist after treatment 2
• Missing underlying conditions: Failure to consider anatomical abnormalities, stones, or other factors that may contribute to enterococcal UTIs 2, 4

In conclusion, the colony count of 50,000-100,000 CFU/mL for Enterococcus faecalis should be considered clinically significant when accompanied by symptoms or pyuria, and appropriate antimicrobial therapy should be initiated based on susceptibility testing.