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Difficulty: EasyInfectious Diseases

A 24-year-old woman presents to the outpatient clinic with a 2-day history of burning with urination and increased urinary frequency. She reports no fever, chills, back pain, or vaginal discharge. She is sexually active with one male partner and uses condoms inconsistently. Her last menstrual period was 2 weeks ago. Vital signs are temperature 37.0°C (98.6°F), blood pressure 110/70 mmHg, pulse 78/min, and respirations 14/min. Physical examination reveals mild suprapubic tenderness but no costovertebral angle tenderness. A urine pregnancy test is negative. Urinalysis is positive for leukocyte esterase and nitrites. Which of the following is the most appropriate pharmacotherapy for this patient?

  1. A
    Oral ciprofloxacin
  2. B
    Oral azithromycin
  3. C
    Intravenous ceftriaxone
  4. Oral nitrofurantoinAnswer
  5. E
    Oral amoxicillin-clavulanate

Answer

Oral nitrofurantoin
This patient presents with classic signs and symptoms of uncomplicated acute cystitis: dysuria, frequency, and suprapubic tenderness, without systemic signs of infection (e.g., fever) or upper tract involvement (e.g., flank pain). Her positive urinalysis confirms the diagnosis. The most appropriate next step is to prescribe targeted, first-line empiric oral antibiotic therapy. Nitrofurantoin is a preferred first-line agent because it is highly concentrated in the urine, has excellent activity against Escherichia coli (the most common uropathogen), and has a narrow spectrum of activity, which aligns perfectly with proper antibiotic stewardship.

Step-by-Step Solution

1
Analyze the clinical presentation.
The patient has dysuria, urinary frequency, and suprapubic tenderness without fever, chills, or costovertebral angle tenderness.
This constellation of symptoms characterizes uncomplicated acute cystitis (lower urinary tract infection) and rules out pyelonephritis (upper urinary tract infection).
2
Interpret the laboratory findings.
Urinalysis is positive for leukocyte esterase (indicating pyuria) and nitrites (indicating the presence of Enterobacteriaceae).
This confirms the diagnosis of a bacterial urinary tract infection, most commonly caused by Escherichia coli.
3
Select the most appropriate pharmacotherapy based on stewardship principles.
Oral nitrofurantoin is chosen over broader-spectrum options.
First-line agents for uncomplicated cystitis include nitrofurantoin, trimethoprim-sulfamethoxazole, and fosfomycin. They are chosen because they achieve high concentrations in the urine, effectively target common uropathogens, and spare broader-spectrum antibiotics (like fluoroquinolones) to prevent resistance.

Key Concept

First-line empiric therapy for uncomplicated acute cystitis should utilize narrow-spectrum agents such as nitrofurantoin, trimethoprim-sulfamethoxazole, or fosfomycin to adhere to antibiotic stewardship principles.
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Topics

Infectious Diseases

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