Can I treat a patient with a large number of leukocytes (white blood cells) in their Urinalysis (UA) for a Urinary Tract Infection (UTI)?

Can You Treat Based on Leukocytes Alone?

No, the presence of leukocytes (pyuria) alone is insufficient to diagnose and treat a UTI—you must have accompanying urinary symptoms (dysuria, frequency, urgency, fever, or gross hematuria) to justify treatment. 1, 2

The Critical Distinction: Symptomatic UTI vs. Asymptomatic Bacteriuria

When Treatment IS Indicated

You can treat for UTI when both of the following are present:

• Pyuria (≥10 WBCs/high-power field or positive leukocyte esterase) 1, 2
• Plus acute onset of UTI-associated symptoms:
  • Dysuria 1, 2
  • Urinary frequency or urgency 1, 2
  • Fever 1, 2
  • Gross hematuria 1, 2
  • New or worsening urinary incontinence (in older adults) 1

When Treatment Should NOT Be Given

Do not treat asymptomatic bacteriuria with pyuria. 1, 2 This is a strong recommendation from the Infectious Diseases Society of America, which explicitly states:

• Urinalysis and urine cultures should not be performed for asymptomatic residents 1
• Asymptomatic bacteriuria with pyuria is extremely common, especially in older adults (prevalence 15-50% in long-term care facility residents) 2
• The absence of pyuria has excellent negative predictive value for ruling out UTI, but the presence of pyuria does NOT confirm infection without symptoms 2

Diagnostic Algorithm

Step 1: Assess for Symptoms

• If symptomatic (dysuria, frequency, urgency, fever, gross hematuria): Proceed to Step 2 1, 2
• If asymptomatic: Stop—do not pursue further testing or treatment 1, 2

Step 2: Obtain Proper Specimen

• For women: In-and-out catheterization is often necessary to avoid contamination 1
• For cooperative men: Midstream clean-catch or clean condom catheter 1
• Critical pitfall: Contaminated specimens with high epithelial cells yield unreliable results 2

Step 3: Perform Urinalysis

• Check for leukocyte esterase, nitrite, and microscopic WBCs 1, 2
• Combined testing improves accuracy: Leukocyte esterase + nitrite has 93% sensitivity and 96% specificity 2, 3
• Leukocyte esterase alone has only 83% sensitivity and 78% specificity 2, 3

Step 4: Order Culture Only If Indicated

• Only proceed to culture if pyuria is present (≥10 WBCs/HPF OR positive leukocyte esterase OR positive nitrite) 1, 2
• Culture with antimicrobial susceptibility testing guides definitive therapy 1

Step 5: Initiate Treatment

• For uncomplicated UTI with symptoms and pyuria, empiric treatment can begin while awaiting culture 4, 5
• Trimethoprim-sulfamethoxazole is FDA-approved for UTI treatment caused by susceptible organisms 4

Special Populations and Common Pitfalls

Older Adults with Cognitive Impairment

• Do not treat bacteriuria with pyuria in patients with delirium, confusion, or falls alone without specific urinary symptoms or systemic signs (fever, hemodynamic instability) 1
• This is a strong recommendation that prioritizes avoiding antimicrobial resistance and Clostridioides difficile infection 1
• Assess for other causes of delirium or falls rather than reflexively treating presumed UTI 1

Long-Term Care Facilities

• Diagnostic evaluation is indicated only with acute onset of UTI-associated symptoms 1
• Non-specific symptoms like confusion or functional decline alone should not trigger UTI treatment 2

Catheterized Patients

• In patients with short-term (<30 days) or long-term indwelling catheters, do not screen for or treat asymptomatic bacteriuria 1
• Evaluation is indicated only if there is suspected urosepsis (fever, shaking chills, hypotension, delirium) 1

Pregnancy and Complicated UTI

• In complicated cases including pregnancy, recurrent infection, or suspected pyelonephritis, both manual microscopy and urine culture with sensitivities are necessary 6

Key Takeaway for Clinical Practice

The presence of "large leukocytes" on UA does not equal UTI. 2 You must distinguish true infection from colonization by requiring both pyuria AND symptoms before initiating treatment. 1, 2 This approach reduces unnecessary antibiotic use, prevents antimicrobial resistance, and avoids adverse drug effects while ensuring appropriate treatment for genuine infections. 1