What are the diagnosis, symptoms, and treatment options for urinary tract infections (UTIs) and acute pyelonephritis in healthy women?

Urinary Tract Infections (UTIs) and Acute Pyelonephritis: Diagnosis, Symptoms, and Treatment

The first-line treatment for uncomplicated UTIs in healthy women is nitrofurantoin 100mg twice daily for 5 days, trimethoprim-sulfamethoxazole (TMP-SMX) 160/800mg twice daily for 3 days (if local resistance <20%), or fosfomycin 3g single dose, with a short course (3-5 days) being sufficient for most cases. 1

Diagnosis of UTIs

Definition

• UTI is defined as greater than 10,000 CFU/mL of one organism
• Positive leukocytes and nitrites on urinalysis support the diagnosis

Clinical Presentation

• Uncomplicated UTI (Cystitis):

  • New onset dysuria
  • Urinary frequency
  • Urgency to urinate
  • Nocturia
  • Suprapubic discomfort
  • Usually no fever
  • Urinalysis shows moderate to large leukocytes, positive nitrites, may have few RBCs, no ketones or protein 2, 1

• Acute Pyelonephritis:

  • Acute onset high fevers and chills
  • Dysuria and frequency
  • Unilateral flank pain (deep ache)
  • Nausea with or without vomiting
  • Costovertebral angle tenderness
  • May have recent history of UTI
  • WBC casts with proteinuria on urinalysis 2, 1

Diagnostic Testing

• Urinalysis showing pyuria (≥10 WBCs/high-power field) or positive leukocyte esterase test indicates need for urine culture 1
• Large numbers of epithelial cells in urine indicate contamination
• In women with typical symptoms, diagnosis can be made with high probability based on history alone without further testing 3
• Urine culture should be obtained for:
  • Suspected pyelonephritis
  • Symptoms that don't resolve within 4 weeks after treatment
  • Women with atypical symptoms
  • Recurrent UTIs
  • Treatment failures 2, 1

Treatment Approach

Uncomplicated UTI in Healthy Women

1. First-line options: 2, 1, 4

   • Nitrofurantoin 100mg twice daily for 5 days
   • TMP-SMX 160/800mg twice daily for 3 days (if local resistance <20%)
   • Fosfomycin 3g single dose

2. Second-line options:

   • Fluoroquinolones (use should be restricted due to increased resistance rates)
   • β-lactams such as amoxicillin-clavulanate 5

3. Duration:

   • 3-day treatment is sufficient for healthy women with uncomplicated UTIs 2, 3

Acute Pyelonephritis

1. Outpatient treatment:

   • Third-generation cephalosporins are preferred 6
   • TMP-SMX for 7-14 days if susceptible 4
   • Consider initial parenteral dose followed by oral therapy

2. Inpatient treatment:

   • Parenteral antibiotics initially
   • Culture-directed therapy for 7-14 days 2, 1

Special Considerations

• Recurrent UTIs: (defined as ≥3 UTIs/year or ≥2 UTIs in 6 months) 2

  • Document positive urine cultures with prior symptomatic episodes
  • Consider patient-initiated treatment for acute episodes while awaiting cultures
  • Prophylactic options include:
    • TMP-SMX 40mg/200mg once daily or three times weekly
    • Nitrofurantoin 50-100mg daily
    • Cephalexin 125-250mg daily
    • Fosfomycin 3g every 10 days 1

• Renal Impairment: 1, 4

  • For CrCl <30 mL/min:
    • Avoid nitrofurantoin
    • Fosfomycin 3g single dose is preferred
    • For TMP-SMX, use half the usual regimen if CrCl 15-30 mL/min, avoid if CrCl <15 mL/min

Monitoring and Follow-up

• Clinical response should be assessed within 48-72 hours of starting treatment
• If symptoms persist beyond 72 hours, obtain urine culture and consider changing antibiotics
• No routine post-treatment urinalysis or cultures are needed for asymptomatic patients 1
• For women whose symptoms do not resolve by the end of treatment or recur within 2 weeks, perform urine culture and antimicrobial susceptibility testing 2

Common Pitfalls and Caveats

1. Overtreatment of asymptomatic bacteriuria:

   • Generally does not require treatment except in pregnant women and high-risk patients 1

2. Misdiagnosis:

   • In elderly women, genitourinary symptoms are not necessarily related to cystitis 2
   • Large numbers of epithelial cells in urine indicate contamination, not infection

3. Antimicrobial resistance:

   • Local resistance patterns should guide empiric therapy
   • TMP-SMX should only be used when local resistance rates are <20% 1, 7
   • Risk of treatment failure is higher with TMP-SMX compared to nitrofurantoin 7

4. Inadequate treatment duration:

   • While 3-day treatment is sufficient for uncomplicated UTIs in healthy women, longer courses (7-14 days) are needed for complicated UTIs and pyelonephritis 2, 1

By following these evidence-based guidelines for diagnosis and treatment, clinicians can effectively manage UTIs and pyelonephritis while minimizing complications and reducing antimicrobial resistance.