Does a female patient with urinary‑tract infection symptoms and a urinalysis showing leukocyte esterase 3+, >30 white blood cells per high‑power field, negative nitrite and no bacteria have a urinary tract infection?

Does This Patient Have a UTI?

No, this patient does not have a urinary tract infection despite the marked pyuria. The combination of 3+ leukocyte esterase with >30 WBCs/hpf but negative nitrite and no visible bacteria on microscopy, in the context of symptoms, represents either sterile pyuria requiring investigation for non-bacterial causes, or more likely a contaminated specimen that needs to be repeated with proper collection technique before any treatment decisions are made.

Critical Diagnostic Interpretation

The absence of bacteria on microscopy is the key finding that argues against bacterial UTI. While pyuria is present, several factors make bacterial infection unlikely:

• Negative nitrite with negative bacteria visualization effectively rules out typical gram-negative uropathogens (E. coli, Klebsiella, Proteus), which cause 80-90% of UTIs and convert nitrates to nitrites 1
• The sensitivity of combined leukocyte esterase and nitrite testing is 93% for detecting UTI, but when bacteria are absent on microscopy despite significant pyuria, this suggests either non-bacterial inflammation or specimen contamination 1
• The presence of pyuria alone has exceedingly low positive predictive value for actual UTI, particularly when specimen quality may be compromised 1

Immediate Next Steps

Obtain a properly collected urine specimen before making any treatment decisions:

• For women: perform in-and-out catheterization to obtain an uncontaminated specimen, as midstream clean-catch specimens frequently show contamination with vaginal flora and epithelial cells 1
• Process the specimen within 1 hour at room temperature or refrigerate if delayed, as bacterial overgrowth in improperly stored specimens can produce false results 1
• Repeat urinalysis AND culture on the properly collected specimen to determine if true pyuria persists and whether bacteria are present 1

Differential Diagnosis for Sterile Pyuria

If repeat properly collected specimen confirms pyuria without bacteria, investigate non-bacterial causes:

• Sexually transmitted infections (chlamydia, gonorrhea) causing urethritis—particularly important in sexually active women with dysuria 2
• Urolithiasis (kidney stones) causing mechanical irritation and inflammation 2
• Interstitial cystitis presenting with chronic bladder inflammation 2
• Tuberculosis of the genitourinary tract, especially if risk factors present 2
• Fungal infection (Candida), particularly in diabetic or immunocompromised patients 2
• Partially treated bacterial infection if patient recently received antibiotics 1

What NOT to Do

Do not start empiric antibiotics based on this urinalysis alone:

• Treating pyuria without confirmed bacterial infection provides no clinical benefit and increases antimicrobial resistance, adverse drug effects, and healthcare costs 1
• The Infectious Diseases Society of America explicitly recommends against treating based on leukocytes alone without accompanying urinary symptoms AND confirmed bacteriuria 1
• Standard UTI antibiotics will not address non-bacterial causes of sterile pyuria and delay appropriate diagnosis 2

Clinical Decision Algorithm

Follow this stepwise approach:

1. Assess for acute onset of specific UTI symptoms: dysuria, urinary frequency, urgency, fever >38.3°C, gross hematuria, or suprapubic pain 1

2. If symptoms are present: Obtain properly collected specimen (catheterization preferred in women) and order BOTH urinalysis and culture before starting antibiotics 1

3. If repeat specimen shows persistent pyuria with negative culture after 48 hours: Evaluate for non-bacterial causes including STI testing, renal/bladder ultrasound for stones, and consideration of TB testing if risk factors present 2

4. If symptoms are absent or non-specific (confusion, functional decline in elderly): Do not pursue UTI testing or treatment, as asymptomatic bacteriuria with pyuria occurs in 15-50% of elderly patients and treatment provides no benefit 1

Special Considerations

The negative nitrite finding is particularly important:

• Nitrite has 98-100% specificity for gram-negative bacterial infection when positive, but its absence does NOT rule out UTI since sensitivity is only 19-48% 1
• However, the combination of negative nitrite AND no visible bacteria on microscopy makes typical bacterial UTI extremely unlikely 1
• Gram-positive organisms (Enterococcus, Staphylococcus saprophyticus) do not produce nitrite, but these should still be visible on microscopy if present in significant numbers 1

Quality of Life and Antimicrobial Stewardship

Avoiding inappropriate antibiotic treatment is critical:

• Unnecessary antibiotics cause harm without benefit: increased resistance, adverse drug reactions (including C. difficile infection), and medication costs 1
• Educational interventions on proper diagnostic protocols provide 33% absolute risk reduction in inappropriate antimicrobial initiation 1
• The key is distinguishing true UTI from asymptomatic bacteriuria or sterile pyuria, which requires both symptoms AND confirmed bacteriuria on properly collected specimens 1, 3