What is the appropriate treatment for a patient with a urinary tract infection indicated by leukoesterase in their urine?

Treatment of Urinary Tract Infection Indicated by Leukocyte Esterase

Positive leukocyte esterase on urinalysis alone is insufficient to diagnose a UTI requiring antibiotics; treatment should be initiated only when positive leukocyte esterase is accompanied by relevant clinical symptoms or additional positive urinalysis findings such as nitrites. 1, 2

Diagnostic Approach

Interpreting Leukocyte Esterase Results

• Leukocyte esterase indicates the presence of white blood cells in urine (pyuria)
• Sensitivity: 83% (range 67-94%)
• Specificity: 78% (range 64-92%) 2
• When used alone, leukocyte esterase has high sensitivity (100%) but moderate specificity (76%) for detecting bacteriuria 3

Diagnostic Algorithm

1. Positive leukocyte esterase + symptoms → Treat empirically while awaiting culture
2. Positive leukocyte esterase + positive nitrites → High probability of UTI (combined sensitivity 93%, specificity 72%) 2
3. Positive leukocyte esterase alone without symptoms → Do not treat; represents asymptomatic bacteriuria in most cases 1, 4
4. Negative leukocyte esterase + nitrites with strong symptoms → Consider treatment as negative results don't completely rule out UTI 1, 4

Key Symptoms Warranting Treatment

• Typical symptoms: Dysuria, frequency, urgency, suprapubic pain
• In older adults: May present atypically with altered mental status, functional decline, fatigue, or falls 1

Treatment Recommendations

First-Line Antibiotics

• Trimethoprim-sulfamethoxazole: 1 DS tablet every 12 hours for 10-14 days (adults) 5
• Nitrofurantoin: Especially effective with good sensitivity patterns 4
• Fosfomycin: Single-dose option with minimal resistance 4

Alternative Options

• Cephalexin: Good option, particularly when leukocyte esterase is positive 6
• Pivmecillinam: Effective with low resistance profiles 7
• Fluoroquinolones: Reserve for complicated infections or when first-line agents cannot be used due to resistance concerns 4

Treatment Duration

• Uncomplicated cystitis: 3-5 days
• Complicated UTIs or pyelonephritis: 7-14 days 2

Special Populations

Pediatric Patients

• Children 2 months to 2 years: 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours, divided twice daily for 10 days 5
• Not recommended for infants under 2 months 5
• Obtain urine culture when starting antibiotics for preliminary UTI diagnosis 1

Elderly Patients

• Treatment generally aligns with other patient groups using the same antibiotics and duration unless complications exist 1
• Do not treat asymptomatic bacteriuria in long-term care facility residents 2
• Consider atypical presentation (confusion, falls, functional decline) 1

Pregnant Women

• Always treat asymptomatic bacteriuria due to increased risks of pyelonephritis and pregnancy complications 2

Important Caveats

• Positive leukocyte esterase without symptoms should not be treated, as asymptomatic bacteriuria is common, particularly in older adults 4
• Urine culture is the gold standard and should be obtained before starting antibiotics 1, 2
• Resistance to trimethoprim-sulfamethoxazole is increasing; local resistance patterns should guide empiric therapy 4
• Nitrofurantoin or cephalexin may be optimal for uncomplicated cystitis given current resistance patterns 6
• Avoid fluoroquinolones for empiric therapy to prevent promotion of resistance 7