What is the likely diagnosis and recommended treatment for a 10‑year‑old girl with dysuria, urinary frequency, suprapubic tenderness, and a urine dipstick showing 75 leukocytes per high‑power field?

Acute Uncomplicated Cystitis in a 10-Year-Old Girl

This 10-year-old girl has acute uncomplicated cystitis and should be treated with nitrofurantoin 5–7 mg/kg/day divided twice daily for 5–7 days, or trimethoprim-sulfamethoxazole 6–12 mg/kg/day (based on trimethoprim component) divided twice daily for 3–5 days if local resistance is <20%. 1, 2

Diagnostic Confirmation

• The combination of 75 leukocytes/HPF (marked pyuria), dysuria, urinary frequency, and suprapubic tenderness establishes the diagnosis of acute cystitis without requiring urine culture in this otherwise healthy child. 1

• Pyuria ≥10 WBC/HPF combined with acute urinary symptoms (dysuria, frequency, suprapubic pain) meets diagnostic criteria for urinary tract infection. 1, 2

• The absence of fever, flank pain, or systemic symptoms (nausea, vomiting, rigors) indicates lower tract infection (cystitis) rather than pyelonephritis. 1, 3

• Urine culture is not mandatory for uncomplicated cystitis in healthy children with typical symptoms and pyuria, though it should be obtained if symptoms persist beyond 48–72 hours or recur within 2–4 weeks. 1, 4

First-Line Treatment Options

Preferred Agent: Nitrofurantoin

• Nitrofurantoin 5–7 mg/kg/day divided twice daily (maximum 100 mg per dose) for 5–7 days is the preferred first-line agent because resistance rates remain <5%, urinary concentrations are high, and gut flora disruption is minimal. 2, 5

• Courses shorter than 5 days have higher failure rates and should be avoided. 2

Alternative: Trimethoprim-Sulfamethoxazole

• Trimethoprim-sulfamethoxazole 6–12 mg/kg/day (based on trimethoprim component) divided twice daily for 3–5 days may be used only if local E. coli resistance is <20% and the child has had no recent exposure to this antibiotic. 2, 4, 5

Agents to Avoid

• Beta-lactam antibiotics (amoxicillin, amoxicillin-clavulanate, cephalosporins) are not recommended for first-line treatment of uncomplicated cystitis due to inferior efficacy and higher resistance rates. 4

• Fluoroquinolones should be reserved for complicated infections or pyelonephritis in children and are not appropriate for simple cystitis. 5

Clinical Reassessment

• Re-evaluate within 48–72 hours to confirm symptom improvement; if dysuria, frequency, or suprapubic pain persist or worsen, obtain urine culture and consider imaging to exclude obstruction or anatomic abnormality. 1, 2

• If symptoms recur within 2–4 weeks after completing treatment, obtain urine culture before starting a second course of antibiotics, as this suggests either treatment failure or reinfection. 4, 6

Common Pitfalls to Avoid

• Do not treat based solely on pyuria without accompanying urinary symptoms; asymptomatic bacteriuria should not be treated in children. 1, 2

• Do not obtain routine post-treatment urine cultures in children whose symptoms resolve completely, as this leads to unnecessary treatment of asymptomatic bacteriuria. 1

• Do not prescribe a 3-day course of nitrofurantoin; the minimum effective duration is 5 days to prevent treatment failure. 2

• Do not delay treatment while awaiting culture results in a child with typical cystitis symptoms and marked pyuria; empiric therapy should be started immediately. 5

When to Consider Imaging

• Imaging (renal/bladder ultrasound) is indicated only if this is a recurrent UTI (≥2 episodes with pyelonephritis or ≥3 episodes of cystitis), if symptoms persist despite appropriate antibiotics, or if there are atypical features suggesting anatomic abnormality. 1, 5

• Routine imaging after a first episode of uncomplicated cystitis in an otherwise healthy child is not recommended. 1