What is the recommended treatment for a complicated urinary tract infection (UTI)?

Treatment of Complicated Urinary Tract Infections

For complicated UTIs, initiate empiric therapy with either IV ceftriaxone 1-2g once daily or piperacillin/tazobactam 2.5-4.5g three times daily for hospitalized or severely ill patients, then transition to oral therapy after clinical improvement for a total duration of 14 days. 1

Initial Diagnostic Approach

• Always obtain urine culture and susceptibility testing before initiating antimicrobial therapy due to the wide spectrum of potential pathogens and increased likelihood of antimicrobial resistance in complicated UTIs 1
• Common pathogens include E. coli, Proteus spp., Klebsiella spp., Pseudomonas spp., Serratia spp., and Enterococcus spp. 1
• All male UTIs should be classified as complicated UTIs, requiring special consideration due to broader microbial spectrum and higher resistance rates 1

Empiric Treatment Selection

For Hospitalized or Severely Ill Patients

Initial IV therapy options include: 1

• Ceftriaxone 1-2g once daily
• Piperacillin/tazobactam 2.5-4.5g three times daily
• Aminoglycoside with or without ampicillin

For Mild Complicated UTIs (Outpatient)

Oral therapy options include: 1, 2

• Levofloxacin 500mg once daily (only if local resistance <10% and no fluoroquinolone use in past 6 months)
• Trimethoprim-sulfamethoxazole 160/800mg twice daily
• Nitrofurantoin (when susceptible)

Critical caveat: Avoid fluoroquinolones as empiric therapy if local resistance rates exceed 10% or if the patient has used fluoroquinolones in the past 6 months 1

Treatment Duration

The standard duration is 14 days for complicated UTIs 1, though recent evidence supports shorter courses in specific scenarios:

• 7 days is appropriate for catheter-associated UTIs with prompt symptom resolution 1
• 10-14 days for catheter-associated UTIs with delayed response 1
• 5 days of levofloxacin 750mg once daily may be considered in patients with mild complicated UTI who are not severely ill 1, 2

Recent guideline evidence from 2023 demonstrates that short-duration therapy (5-7 days) results in similar clinical success as long-duration therapy (10-14 days), even in patients with bacteremia 3. However, one subgroup analysis showed 7-day ciprofloxacin was inferior to 14-day therapy in men (86% vs 98% cure rate), though a subsequent adequately powered study found 7-day courses non-inferior despite high rates of anatomic abnormalities 3. Given this conflicting evidence, the safer approach is to default to 14 days, particularly in males where prostatitis cannot be excluded. 1

Transition to Oral Therapy

Switch to oral therapy when: 1

• Patient is hemodynamically stable
• Afebrile for at least 48 hours
• Able to tolerate oral medications

Reassess after 48-72 hours of empiric therapy to evaluate clinical response and adjust based on culture and susceptibility results 1

Special Considerations

Catheter-Associated UTIs

• Replace the catheter if it has been in place ≥2 weeks at onset of infection and is still indicated, as this hastens symptom resolution 1

Male Patients

• Require 14-day treatment courses when prostatitis cannot be excluded 1
• Do not use shorter treatment courses (<14 days) unless prostatitis has been definitively excluded 1

Antimicrobial Stewardship

• Avoid carbapenems and novel broad-spectrum antimicrobials unless culture results indicate multidrug-resistant organisms 1
• Complete the full course even after symptom resolution to prevent relapse 1

Common Pitfalls to Avoid

• Do not treat asymptomatic bacteriuria in non-pregnant patients 1
• Do not use fluoroquinolones empirically if resistance rates are high or recent fluoroquinolone exposure 1
• Do not shorten treatment duration in males without excluding prostatitis 1
• Do not skip culture and susceptibility testing before initiating therapy, as this is essential for tailoring treatment in complicated UTIs 1