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

Treatment of Complicated Urinary Tract Infections

Recommended Treatment Approach

For complicated UTIs, initiate empiric therapy with either levofloxacin 750 mg once daily for 5 days (for mild cases) or standard 14-day regimens, always obtaining urine culture and susceptibility testing before starting antibiotics to guide definitive therapy. 1

Initial Diagnostic Steps

• Obtain urine culture and susceptibility testing before initiating antimicrobial therapy due to the wide spectrum of potential infecting organisms 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 likelihood of antimicrobial resistance 1

Empiric Treatment Selection

For Hospitalized or Severe Infections:

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

For Mild to Moderate Outpatient Cases:

• Levofloxacin 750 mg once daily for 5 days is FDA-approved for complicated UTIs caused by E. coli, Klebsiella pneumoniae, or Proteus mirabilis 2
• Levofloxacin 500 mg once daily for 14 days after clinical improvement 1
• Trimethoprim-sulfamethoxazole 160/800mg twice daily for 14 days 1

Fluoroquinolone Use Restrictions:

• Only use fluoroquinolones when local resistance rates are <10% 1
• Avoid if patient has used fluoroquinolones in the past 6 months 1
• Recent 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 1

Treatment Duration Guidelines

Standard Duration:

• 14 days is the standard duration for complicated UTIs 1
• 7 days for catheter-associated UTIs with prompt symptom resolution 3, 1
• 10-14 days for catheter-associated UTIs with delayed response 3, 1

Shortened Duration Options:

• 5-day levofloxacin 750mg regimen may be considered in patients with mild complicated UTI who are not severely ill 1, 2
• However, one subgroup analysis showed 7-day ciprofloxacin was inferior to 14-day therapy in men, so exercise caution with shortened courses in male patients 1

Special Considerations for Catheter-Associated UTIs

• Replace the catheter if it has been in place for ≥2 weeks at onset of CA-UTI and is still indicated to hasten resolution of symptoms and reduce risk of subsequent bacteriuria 3, 1
• Remove the urinary catheter as soon as clinically appropriate 3
• A 3-day antimicrobial regimen may be considered for women aged ≤65 years who develop CA-UTI without upper urinary tract symptoms after an indwelling catheter has been removed 3

Male-Specific Considerations

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

Monitoring and Adjustment

• Reassess after 48-72 hours of empiric therapy to evaluate clinical response 1
• Adjust therapy based on culture and susceptibility results 1
• Switch to oral therapy when patient is hemodynamically stable and has been afebrile for at least 48 hours 1
• Treatment may need to be extended and urologic evaluation performed if patient does not have prompt clinical response with defervescence by 72 hours 3

Critical Pitfalls to Avoid

• Do not treat asymptomatic bacteriuria in non-pregnant patients 1
• Avoid carbapenems and novel broad-spectrum antimicrobials unless culture results indicate multidrug-resistant organisms 1
• Avoid fluoroquinolones as empiric therapy if local resistance rates exceed 10% 1
• Do not use moxifloxacin for UTI treatment due to uncertainty regarding effective urinary concentrations 3
• Complete the full course even after symptom resolution to prevent relapse 1