What is the recommended treatment for a patient with a urinary tract infection (UTI) indicated by a urine analysis showing more than 100 white blood cells (WBCs)?

Treatment of UTI with >100 WBCs on Urinalysis

For a patient with urinary tract infection indicated by >100 WBCs on urinalysis, treatment should be guided by whether the infection is uncomplicated or complicated, with first-line therapy being nitrofurantoin (100 mg twice daily for 5 days) or fosfomycin (3g single dose) for uncomplicated cystitis in women, and broader spectrum antibiotics for complicated infections or pyelonephritis. 1

Classification and Initial Assessment

The presence of >100 WBCs on urinalysis indicates significant pyuria and strongly suggests active urinary tract infection requiring treatment. 2, 3 However, the specific treatment approach depends critically on distinguishing between uncomplicated and complicated UTI:

Uncomplicated Cystitis (Non-pregnant, Premenopausal Women)

First-line treatment options include: 1

• Fosfomycin trometamol 3g single dose (recommended only for women with uncomplicated cystitis)
• Nitrofurantoin 100 mg twice daily for 5 days (macrocrystals, monohydrate, or prolonged release formulations)
• Pivmecillinam 400 mg three times daily for 3-5 days

Alternative agents if local E. coli resistance is <20%: 1

• Cephalosporins (e.g., cefadroxil 500 mg twice daily for 3 days)
• Trimethoprim 200 mg twice daily for 5 days (avoid in first trimester pregnancy)
• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days (avoid in last trimester pregnancy)

Important caveat: Urine culture is not routinely required for typical uncomplicated cystitis presentations, as it provides minimal increase in diagnostic accuracy. 1 However, obtain culture if symptoms are atypical, do not resolve within 4 weeks, or if the patient is pregnant. 1

Uncomplicated Pyelonephritis

For patients with fever (>38°C), flank pain, costovertebral angle tenderness, or systemic symptoms: 1

Outpatient oral therapy: 1

• Fluoroquinolones (if local resistance <10%)
• Oral cephalosporins (though they achieve lower blood/urinary concentrations than IV route)

Inpatient IV therapy: 1

• Fluoroquinolone IV
• Aminoglycoside (with or without ampicillin)
• Extended-spectrum cephalosporin or penicillin
• Duration: 7-14 days 1

Critical action: Obtain urine culture and antimicrobial susceptibility testing in ALL cases of pyelonephritis before initiating treatment. 1

Complicated UTI

Complicated UTI occurs with underlying urological abnormalities, obstruction, foreign bodies (including catheters), male sex, pregnancy, diabetes, immunosuppression, healthcare-associated infection, or multidrug-resistant organisms. 1

Empirical treatment for complicated UTI with systemic symptoms: 1

• Amoxicillin plus aminoglycoside
• Second-generation cephalosporin plus aminoglycoside
• IV third-generation cephalosporin

Duration: 7-14 days (14 days for men when prostatitis cannot be excluded). 1 Treatment duration should be closely related to management of the underlying abnormality. 1

Fluoroquinolone considerations: Only use ciprofloxacin if local resistance rate is <10%, the entire treatment can be given orally, the patient doesn't require hospitalization, or the patient has anaphylaxis to β-lactams. 1 Do NOT use fluoroquinolones empirically in patients from urology departments or who have used fluoroquinolones in the last 6 months. 1

Catheter-Associated UTI

For patients currently catheterized or catheterized within past 48 hours with compatible symptoms (fever, altered mental status, flank pain, suprapubic pain): 1

Treatment approach: 1

• Remove or replace catheter when possible
• 7-14 day antimicrobial regimen regardless of whether catheter remains 1
• 5-day levofloxacin may be considered for non-severely ill patients 1
• 3-day regimen may be considered for women ≤65 years without upper tract symptoms after catheter removal 1

Treatment in Special Populations

Men with UTI

• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 7 days 1
• Fluoroquinolones can be prescribed according to local susceptibility testing 1

Pediatric Patients (2-24 months with febrile UTI)

Oral or parenteral routes are equally efficacious: 1

Parenteral options: 1

• Ceftriaxone 75 mg/kg every 24 hours
• Cefotaxime 150 mg/kg/day divided every 6-8 hours
• Gentamicin 7.5 mg/kg/day divided every 8 hours

Oral options: 1

• Amoxicillin-clavulanate 20-40 mg/kg/day in 3 doses
• Cephalosporins (cefixime, cefpodoxime, cefuroxime)

Duration: 7-14 days 1

Multidrug-Resistant Organisms

For carbapenem-resistant Enterobacterales (CRE) causing complicated UTI: 1

• Ceftazidime-avibactam 2.5g IV every 8 hours 1
• Meropenem-vaborbactam 4g IV every 8 hours 1
• Imipenem-cilastatin-relebactam 1.25g IV every 6 hours 1
• Plazomicin 15 mg/kg IV every 12 hours 1
• Single-dose aminoglycoside for simple cystitis due to CRE 1

Common Pitfalls to Avoid

1. Do NOT treat asymptomatic bacteriuria - even with significant pyuria, treatment without symptoms may be harmful. 1

2. Do NOT use nitrofurantoin, fosfomycin, or pivmecillinam for pyelonephritis - insufficient data regarding efficacy for upper tract infections. 1

3. Do NOT routinely perform post-treatment urinalysis or cultures in asymptomatic patients - only obtain if symptoms persist or recur within 2-4 weeks. 1

4. Do NOT use trimethoprim-sulfamethoxazole empirically if local E. coli resistance exceeds 20% - switch to alternative agents. 4

5. Do NOT use moxifloxacin for UTI - uncertainty regarding effective urinary concentrations. 1

6. Obtain imaging (ultrasound or CT) if patient remains febrile after 72 hours of treatment - to rule out obstruction, abscess, or other complications. 1