Do we treat a urine culture with 10,000 to 49,000 CFU/mL of Enterococcus faecalis?

Management of Urine Culture with 10,000 to 49,000 CFU/mL Enterococcus faecalis

Asymptomatic bacteriuria with Enterococcus faecalis at 10,000-49,000 CFU/mL should not be treated with antibiotics unless the patient belongs to specific high-risk categories.

Decision Algorithm for Treatment

Step 1: Determine if the patient is symptomatic

• Symptomatic UTI signs/symptoms:
  • Dysuria (painful urination)
  • Frequency
  • Urgency
  • Suprapubic pain
  • Hematuria
  • Fever (if upper tract involvement)

Step 2: Evaluate colony count and pyuria

• Colony count 10,000-49,000 CFU/mL is below the traditional threshold (100,000 CFU/mL) for diagnosis
• Check for pyuria (≥10 WBC/mm³ or ≥5 WBC/HPF on centrifuged specimen)
• The combination of symptoms + pyuria + bacteriuria is more important than colony count alone 1

Step 3: Determine patient category

Treat if the patient belongs to these categories (even with lower colony counts):

1. Pregnant women (screen and treat all bacteriuria) 2
2. Pre-urologic procedure where mucosal bleeding is anticipated 2
3. Symptomatic patients with pyuria and clinical signs of UTI 1

Do NOT treat in these categories:

1. Asymptomatic non-pregnant women 2
2. Asymptomatic diabetic women 2
3. Asymptomatic elderly persons (community or institutionalized) 2
4. Asymptomatic patients with spinal cord injury 2
5. Catheterized patients while catheter remains in place 2
6. Renal transplant recipients >1 month post-transplant 2

Evidence Analysis

Colony Count Significance

The traditional threshold of 100,000 CFU/mL was established decades ago, but more recent evidence suggests lower counts can be clinically significant. The American Academy of Pediatrics recommends a threshold of ≥50,000 CFU/mL when combined with pyuria and symptoms 1. However, in symptomatic patients, counts as low as 10,000 CFU/mL may be clinically relevant 3.

Enterococcus faecalis Considerations

• E. faecalis is often part of normal gut flora and can cause endogenous UTIs 4
• In a study of paired urine and stool samples, 26.9% of E. faecalis UTIs showed identical strains between urine and stool, confirming endogenous infection route 4
• E. faecalis UTIs are associated with urinary catheterization and recent antibiotic use 5
• E. faecalis shows lower resistance rates compared to E. faecium 5

Treatment Recommendations (if treatment is indicated)

If the patient is symptomatic and treatment is warranted:

1. First-line options:

   • Nitrofurantoin (preferred due to lower resistance rates) 1
   • Fosfomycin trometamol (single 3g dose) 1

2. Alternative options:

   • Trimethoprim-sulfamethoxazole (only in areas with <20% resistance) 1
   • Ciprofloxacin (for complicated UTIs with E. faecalis) 6
   • Levofloxacin (for complicated UTIs with E. faecalis) 7

Important Caveats

• Specimen collection is critical: Improper collection can lead to false positives 1
• Processing time matters: Urine should be processed within 2 hours or refrigerated 1
• Avoid routine post-treatment testing in asymptomatic patients 1
• Overtreatment of asymptomatic bacteriuria contributes to antimicrobial resistance 1
• Special consideration for renal transplant patients: A retrospective study showed no benefit of treating asymptomatic bacteriuria in renal transplant recipients >1 month post-transplant 2
• E. faecalis vs E. faecium: E. faecium infections tend to be more severe and have higher mortality rates than E. faecalis (23% vs. 10.1%) 5

Remember that treating asymptomatic bacteriuria in most patient populations provides no benefit and contributes to antimicrobial resistance, adverse drug effects, and increased healthcare costs.