Treatment for UTI with 1+ Nitrite and Leukocyte Esterase 500 in Urine
For a urinary tract infection with 1+ nitrite and leukocyte esterase 500 in urine, first-line treatment options include nitrofurantoin, trimethoprim-sulfamethoxazole (TMP-SMX), or fosfomycin, with nitrofurantoin being the preferred option due to lower resistance rates. 1
Diagnostic Significance
The presence of both nitrite and leukocyte esterase in urine is highly suggestive of a urinary tract infection:
- Nitrite positive: Indicates presence of bacteria that convert nitrates to nitrites (typically gram-negative organisms)
- Leukocyte esterase positive: Indicates presence of white blood cells, suggesting inflammation
Combined sensitivity of these markers ranges from 46-100% with specificity of 42-98% 1, making this a reliable indicator of UTI requiring treatment.
Treatment Algorithm
First-line options:
Nitrofurantoin 100mg twice daily for 5 days
- Preferred due to lower resistance rates
- Effective against most common uropathogens including E. coli
Trimethoprim-sulfamethoxazole 160/800mg (double strength) twice daily for 3 days
- Only if local resistance rates are <20%
- FDA-approved for UTIs caused by E. coli, Klebsiella, Enterobacter, Morganella morganii, Proteus mirabilis and Proteus vulgaris 2
Fosfomycin trometamol 3g single dose
- Convenient single-dose therapy
- Good option for patients with compliance concerns 1
Second-line options (if first-line contraindicated or not appropriate):
- Cephalexin or cefixime
- Amoxicillin-clavulanate
- Fluoroquinolones (only if other options unavailable due to resistance concerns) 3
Special Considerations
Factors that may influence treatment choice:
- Local resistance patterns: Approximately 26% of empirically treated UTIs require antibiotic change due to resistance 4
- Patient risk factors for resistant organisms:
- Recent antibiotic exposure
- Healthcare-associated infection
- Immunosuppression (associated with 12% vs 2% antibiotic change rate) 4
- Presence of urological abnormalities
Complicated vs. Uncomplicated UTI
If any of these factors are present, consider the UTI complicated 5:
- Obstruction at any site in the urinary tract
- Foreign body presence
- Incomplete voiding
- Male gender
- Pregnancy
- Diabetes mellitus
- Immunosuppression
- Recent instrumentation
- Healthcare-associated infection
For complicated UTIs, consider broader spectrum coverage and longer treatment duration, with therapy tailored to local resistance patterns 5.
Follow-up Recommendations
- Patients should be instructed to return if symptoms persist or worsen after 48-72 hours of treatment
- No need for repeat urinalysis if symptoms resolve 1
- For recurrent UTIs, consider urine culture to guide therapy
Important Caveats
- Avoid treating asymptomatic bacteriuria (positive nitrite/leukocyte esterase without symptoms) except in pregnancy or before urological procedures 1
- De-escalate to narrower spectrum antibiotics when culture results become available 1
- The presence of both nitrite and leukocyte esterase has a negative predictive value of 95% for UTI 6, meaning a negative test for both makes UTI unlikely
By following this treatment approach based on current guidelines, you can effectively manage UTIs while promoting antimicrobial stewardship.