Should a urine culture with 55,000–100,000 CFU/mL Enterococcus faecalis be treated?

Should a Urine Culture with 55,000–100,000 CFU/mL Enterococcus faecalis Be Treated?

No, this finding should not be treated unless the patient has both acute urinary symptoms (dysuria, frequency, urgency, fever >38.3°C, or gross hematuria) AND documented pyuria (≥10 WBC/HPF or positive leukocyte esterase). 1, 2

Diagnostic Criteria Required Before Treatment

Treatment of any suspected urinary tract infection requires both of the following:

• Acute urinary symptoms: dysuria, urinary frequency, urgency, suprapubic pain, fever >38.3°C, gross hematuria, or costovertebral angle tenderness 1, 2
• Pyuria: ≥10 white blood cells per high-power field on microscopy OR positive leukocyte esterase test 1, 2

If either criterion is absent, antibiotics should not be prescribed. 1, 2

Colony Count Interpretation

• The traditional threshold for significant bacteriuria is ≥100,000 CFU/mL in asymptomatic adults 1, 3
• Your culture result of 55,000–100,000 CFU/mL falls into an intermediate zone that requires clinical correlation 2, 4
• In symptomatic patients with pyuria, even lower counts (≥1,000 CFU/mL) can represent true infection 4, 5
• In asymptomatic patients, this colony count does not meet the threshold for significant bacteriuria and should not be treated 1, 3

Special Considerations for Enterococcus faecalis

• Enterococcus faecalis is a common cause of complicated urinary tract infections, particularly in catheterized patients or those with structural abnormalities 1, 3
• In renal transplant recipients >1 month post-surgery, asymptomatic E. faecalis bacteriuria should not be treated, as it does not prevent pyelonephritis or improve graft function 1
• Spontaneous clearance of asymptomatic enterococcal bacteriuria occurs in 57% of untreated episodes, similar to the 59% microbiologic cure rate with antimicrobial treatment 1

Harms of Treating Asymptomatic Bacteriuria

The 2019 IDSA guidelines issue a strong recommendation (Grade A-II) against treating asymptomatic bacteriuria in virtually all populations. 1, 2

Treatment of asymptomatic bacteriuria:

• Does not prevent symptomatic UTI or renal injury 1, 6
• Increases antimicrobial resistance and promotes reinfection with more resistant organisms 1, 7, 6
• Increases adverse drug events including Clostridioides difficile infection 1, 2
• Provides no clinical benefit while exposing patients to unnecessary medication side effects 1, 6

Exceptions Where Treatment IS Indicated

Treatment of asymptomatic bacteriuria is recommended only in:

1. Pregnant women (screen in first trimester) to prevent pyelonephritis, preterm delivery, and low birth-weight infants 1, 2, 3
2. Patients undergoing urologic procedures with anticipated mucosal bleeding to reduce postoperative sepsis risk 1, 2, 3

Clinical Decision Algorithm

Step 1: Assess for acute urinary symptoms (dysuria, frequency, urgency, fever >38.3°C, gross hematuria) 1, 2

• If NO symptoms: Do not treat; this represents asymptomatic bacteriuria 1, 2
• If symptoms present: Proceed to Step 2

Step 2: Verify pyuria (≥10 WBC/HPF or positive leukocyte esterase) 1, 2

• If NO pyuria: Do not treat; bacterial UTI is unlikely (negative predictive value 82–91%) 2
• If pyuria present: Proceed to Step 3

Step 3: Confirm proper specimen collection 1, 2

• Women: in-and-out catheterization preferred to avoid contamination 1, 2
• Men: midstream clean-catch after thorough cleansing 1, 2
• If mixed flora or high epithelial cells: recollect specimen before treating 2

Step 4: If both symptoms AND pyuria are confirmed, initiate empiric therapy and obtain culture with susceptibilities 2

Common Pitfalls to Avoid

• Never treat based on colony count alone without confirming symptoms and pyuria 1, 2
• Do not assume pyuria equals infection—15–50% of elderly adults have asymptomatic bacteriuria with pyuria 1, 2
• Non-specific symptoms in elderly patients (confusion, falls, functional decline) do not justify treatment without specific urinary symptoms 1, 2
• Catheterized patients have near-universal bacteriuria and pyuria; treat only when fever, hypotension, rigors, or suspected urosepsis are present 1, 2, 7
• Cloudy or foul-smelling urine alone should not trigger treatment in asymptomatic individuals 2

Antimicrobial Stewardship Impact

• Inappropriate treatment of asymptomatic bacteriuria is a major contributor to antimicrobial overuse in hospitals 7
• In one study, 32% of catheter-associated asymptomatic bacteriuria episodes were inappropriately treated with antibiotics 7
• Educational interventions on proper diagnostic protocols achieve a 33% absolute risk reduction in inappropriate antimicrobial initiation 2