How do you distinguish and treat lower vs upper urinary tract infections (UTIs)?

Distinguishing and Treating Lower vs Upper Urinary Tract Infections (UTIs)

Lower UTIs (cystitis) and upper UTIs (pyelonephritis) require different diagnostic approaches and treatment regimens based on their distinct clinical presentations and severity. The proper identification and management of these infections is crucial for reducing morbidity and mortality.

Clinical Presentation and Diagnosis

Lower UTI (Cystitis)

• Presents with dysuria, frequency, urgency, and suprapubic pain/tenderness without fever 1
• Absence of vaginal discharge helps distinguish from vaginitis 1
• Typically no systemic symptoms like fever or flank pain 2
• Diagnosis can be made with high probability based on focused history of lower urinary tract symptoms 1
• Urine analysis provides minimal increase in diagnostic accuracy when symptoms are typical 1

Upper UTI (Pyelonephritis)

• Characterized by fever, flank pain, costovertebral angle tenderness, and often acute hematuria 1
• May include systemic symptoms: rigor, altered mental status, malaise, or lethargy 1
• Can progress to urosepsis with life-threatening organ dysfunction 1
• Repeated episodes of pyelonephritis should prompt consideration of complicated etiology 1
• Requires urine culture before initiating antimicrobial therapy 1

Diagnostic Testing

When to Perform Urine Culture

• Always obtain for suspected acute pyelonephritis 1
• Recommended when symptoms don't resolve or recur within 4 weeks after treatment 1
• Necessary for women presenting with atypical symptoms 1
• Required for pregnant patients 1
• Not necessary for uncomplicated lower UTIs with typical presentation 2

Imaging Studies

• Not routinely indicated for uncomplicated lower UTIs 1
• Consider upper tract imaging (ultrasound, CT) for patients with febrile UTI that doesn't respond to appropriate antibiotic therapy 1
• Imaging warranted for recurrent UTIs with the same organism (relapses) or rapid recurrence after treatment 1
• CT urography or MR urography may be necessary for complicated cases to evaluate structural abnormalities 1

Treatment Approaches

Lower UTI (Uncomplicated Cystitis)

• First-line treatment options:
  • Fosfomycin trometamol 3g single dose 1
  • Nitrofurantoin 100mg twice daily for 5 days 1
  • Pivmecillinam 400mg three times daily for 3-5 days 1
• Alternative options:
  • Cephalosporins (e.g., cefadroxil) 500mg twice daily for 3 days (if local E. coli resistance <20%) 1
  • Trimethoprim 200mg twice daily for 5 days (avoid in first trimester of pregnancy) 1
  • Trimethoprim-sulfamethoxazole 160/800mg twice daily for 3 days (avoid in last trimester of pregnancy) 3
• Short-course therapy (3-5 days) is generally sufficient 1
• For mild to moderate symptoms, symptomatic therapy (e.g., ibuprofen) may be considered as an alternative to antimicrobials 1

Upper UTI (Complicated UTI with Systemic Symptoms)

• Requires more aggressive treatment with:
  • Amoxicillin plus an aminoglycoside, OR
  • A second-generation cephalosporin plus an aminoglycoside, OR
  • An intravenous third-generation cephalosporin 1
• Only use ciprofloxacin if local resistance rate is <10% and:
  • The entire treatment can be given orally, OR
  • The patient doesn't require hospitalization, OR
  • The patient has anaphylaxis to β-lactam antimicrobials 1
• Avoid fluoroquinolones for empirical treatment if patient has used them in the last 6 months 1
• Manage any urological abnormality and/or underlying complicating factors 1
• Longer treatment duration (typically 7-14 days) is necessary 3

Special Considerations

Catheter-Associated UTI (CA-UTI)

• Signs and symptoms include fever, rigor, altered mental status, flank pain, and pelvic discomfort 1
• Treat symptomatic CA-UTI according to recommendations for complicated UTI 1
• Replace or remove the indwelling catheter before starting antimicrobial therapy 1
• Do not treat catheter-associated asymptomatic bacteriuria in general 1
• Obtain urine culture before initiating antimicrobial therapy in catheterized patients whose catheter has been removed 1

Recurrent UTIs

• Defined as at least three UTIs/year or two UTIs in the last 6 months 1
• Diagnose via urine culture 1
• Non-antimicrobial interventions should be tried first:
  • Increased fluid intake 1
  • Vaginal estrogen replacement in postmenopausal women 1
  • Immunoactive prophylaxis 1
  • Probiotics containing strains effective for vaginal flora regeneration 1
  • Cranberry products (though evidence is contradictory) 1
• Consider antimicrobial prophylaxis only when non-antimicrobial measures fail 4

Common Pitfalls to Avoid

• Treating asymptomatic bacteriuria (except before urologic procedures) 1
• Using fluoroquinolones empirically when local resistance rates are high 1
• Failing to distinguish between lower and upper UTI, leading to inappropriate treatment duration 2
• Not obtaining urine culture before treatment in complicated or recurrent cases 1
• Overlooking structural abnormalities in patients with recurrent pyelonephritis 1
• Neglecting to replace or remove indwelling catheters before starting antimicrobial therapy 1