What is the best management approach for a 70-year-old man with recurrent Urinary Tract Infections (UTIs) and no apparent anatomical issues on Computed Tomography (CT) scan and cystoscopy?

Management of Recurrent UTIs in a 70-Year-Old Man with Negative Workup

In a 70-year-old man with recurrent UTIs and negative anatomical evaluation, the primary management strategy should focus on antimicrobial prophylaxis or patient-initiated treatment for acute episodes, as further imaging or cystoscopy is not indicated when initial comprehensive evaluation is unrevealing.

Initial Considerations

Since this patient has already undergone CT scan, cystoscopy, and post-void residual assessment with negative findings, he falls into the category of recurrent uncomplicated UTIs without identifiable anatomical abnormalities. The European Association of Urology guidelines recommend against routine cystoscopy in patients with recurrent UTI and no risk factors 1. Additional imaging with CT urography is primarily indicated for complicated recurrent UTIs with suspected structural abnormalities, which have already been excluded in this case 2.

Treatment Strategies for Acute Episodes

For each symptomatic episode, treatment should be initiated promptly based on culture and susceptibility testing:

• First-line antibiotics should be selected based on local resistance patterns and previous culture results 3
• Nitrofurantoin 50-100 mg four times daily for 5 days is recommended as a first-line option 3
• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days is an alternative first-line choice 3, 4
• Fosfomycin trometamol 3 g single dose is another effective first-line option 3, 5

Prophylaxis Strategies

When non-antimicrobial interventions fail or recurrences are frequent, antimicrobial prophylaxis becomes necessary:

Continuous Prophylaxis

• Low-dose antimicrobial prophylaxis using nitrofurantoin 50 mg, trimethoprim-sulfamethoxazole 40/200 mg, or trimethoprim 100 mg daily has been demonstrated effective 3, 6
• Duration typically ranges from 6-12 months 3
• This approach reduces clinical recurrences approximately 6-fold compared to placebo 5

Post-Coital Prophylaxis

If UTIs appear temporally related to sexual activity:

• Post-coital trimethoprim-sulfamethoxazole is highly effective, reducing infection rates from 3.6 to 0.3 per patient-year 7
• This strategy is as effective as continuous prophylaxis but uses fewer antibiotics 6, 7

Patient-Initiated Treatment

• Self-initiated antibiotic therapy at first symptoms is the strategy that results in lowest overall antibiotic exposure 5
• Patients should be educated to recognize symptoms early and have antibiotics available 5, 6

Non-Antimicrobial Measures

While evidence is limited in men compared to postmenopausal women, consider:

• Methenamine hippurate as a non-antibiotic alternative for prevention 3
• Adequate hydration and avoiding prolonged urine retention 3
• Cranberry products have modest efficacy in reducing recurrence frequency 5, 8

Clinical Algorithm

1. Confirm true recurrent UTIs with urine culture documentation (≥3 episodes per year or ≥2 in 6 months) 3
2. Obtain culture and susceptibility testing with each symptomatic episode before treatment 3
3. Assess pattern of recurrences: frequency, temporal relationship to activities, and previous antibiotic responses 6
4. Choose prophylaxis strategy based on:
   • High frequency (≥3/year): Consider continuous prophylaxis 3, 6
   • Lower frequency or patient preference: Patient-initiated treatment 5, 6
   • Pattern related to specific triggers: Post-coital or situational prophylaxis 7

Important Caveats

• Do not pursue additional imaging unless new symptoms suggest obstruction, hematuria develops, or treatment failures occur despite appropriate antibiotics 2, 1
• Antibiotic selection must account for local resistance patterns and the patient's previous culture results 3, 6
• Monitor for adverse effects and development of antimicrobial resistance, which argues for using the minimum necessary antibiotic exposure 5, 8
• Reassess if pattern changes: New onset hematuria, obstructive symptoms, or failure to respond to appropriate antibiotics warrants repeat cystoscopy 1