How to treat a UTI with positive nitrites but no leukocytes?

Treatment of UTI with Positive Nitrites but No Leukocytes

Treat with antibiotics if the patient has urinary symptoms (dysuria, frequency, urgency, fever, or gross hematuria), but do NOT treat if asymptomatic—this represents asymptomatic bacteriuria which should not receive antibiotics except in pregnancy or before urologic procedures. 1

Diagnostic Interpretation

Nitrite positivity is highly specific (98%) for bacterial infection and strongly indicates true bacteriuria, even without leukocytes. 1 The absence of leukocytes does NOT rule out UTI because:

• Nitrite reflects bacterial conversion of dietary nitrates, which occurs independently of the inflammatory response 1
• The combination of positive nitrite with negative leukocyte esterase can still represent genuine infection, particularly early in the disease course 2
• Approximately 50% of samples with both negative nitrite and negative leukocyte esterase are culture-positive, so a positive nitrite alone carries significant diagnostic weight 2

Treatment Algorithm

Step 1: Assess for Symptoms

Determine if the patient has ANY of the following urinary symptoms: 1

• Dysuria
• Urinary frequency
• Urinary urgency
• Fever
• Costovertebral angle tenderness
• Gross hematuria
• New or worsening urinary incontinence

Step 2: Decision Point

If SYMPTOMATIC: 1

• Collect urine culture BEFORE starting antibiotics using proper technique (catheterization in young children, midstream clean-catch in cooperative adults) 1
• Initiate empiric antibiotic therapy immediately after culture collection 1
• First-line options: nitrofurantoin or trimethoprim-sulfamethoxazole (if local resistance <20%) 3, 2
• Duration: 3-5 days for uncomplicated UTI 4
• Avoid fluoroquinolones as first-line—reserve for complicated infections or when first-line agents contraindicated 1

If ASYMPTOMATIC: 1

• Do NOT treat with antibiotics 1
• This represents asymptomatic bacteriuria, which has a prevalence of 15-50% in elderly populations 5
• Treatment leads to unnecessary antibiotic exposure, resistance development, and adverse effects without clinical benefit 4
• Exceptions requiring treatment: pregnancy or immediately before urologic procedures with anticipated mucosal disruption 4

Special Population Considerations

Febrile Infants and Children <2 Years

• Always obtain urine culture regardless of urinalysis results because 10-50% of culture-proven UTIs have false-negative urinalysis in this age group 1, 4
• Use catheterization or suprapubic aspiration for specimen collection 1
• Nitrite sensitivity is particularly poor in young infants due to frequent voiding and insufficient bladder dwell time 4

Elderly and Long-Term Care Residents

• Do NOT treat positive nitrites without specific urinary symptoms 1
• Asymptomatic bacteriuria prevalence is 15-50% in this population 1
• Non-specific symptoms like confusion, falls, or functional decline alone do NOT justify UTI treatment 5
• Evaluate only with acute onset of fever, dysuria, gross hematuria, or suspected bacteremia 5

Catheterized Patients

• Do NOT screen for or treat asymptomatic bacteriuria, even with positive nitrites 1
• Reserve testing and treatment only for symptomatic patients with fever, hypotension, or specific urinary symptoms 5

Critical Pitfalls to Avoid

Never treat positive nitrites without urinary symptoms—this is the single most common error leading to unnecessary antibiotic use and resistance 1, 6. A systematic review found that 45% of asymptomatic patients with positive cultures are inappropriately treated, with positive nitrites being a significant predictor of overtreatment (OR 3.83) 6.

Do not delay culture collection—always obtain culture before starting antibiotics in cases with positive nitrites to guide definitive therapy and document susceptibility patterns 1.

Do not continue antibiotics beyond 3-5 days for uncomplicated UTI—longer courses increase resistance without additional clinical benefit 1.

Do not assume negative leukocytes rules out infection—research shows that even with negative dipstick for both leucocytes and nitrites, antibiotics significantly reduced dysuria (median resolution 3 days vs 5 days, NNT=4) 7. However, this finding applies to symptomatic patients, not asymptomatic screening.

Antibiotic Selection Considerations

When treatment is indicated, consider local resistance patterns: 2

• Trimethoprim resistance has reached 20% in some regions, potentially limiting its use as first-line therapy 2
• Nitrofurantoin maintains excellent susceptibility for E. coli (the most common uropathogen) 2
• Fluoroquinolone resistance is emerging, particularly in older patients 2
• Enterococcus (which doesn't produce nitrite) represents only 3% of nitrite-negative UTIs in young children, so absence of nitrite should not routinely affect empiric antibiotic choice 8