Antibiotic Treatment for Pseudomonas aeruginosa UTI
For susceptible Pseudomonas aeruginosa UTI, use ciprofloxacin 500-750 mg twice daily or levofloxacin 750 mg once daily for 7-10 days if local fluoroquinolone resistance is <10%; for multidrug-resistant or difficult-to-treat Pseudomonas, use ceftolozane/tazobactam 1.5 g IV every 8 hours or ceftazidime/avibactam 2.5 g IV every 8 hours as first-line therapy. 1, 2, 3
Treatment Algorithm Based on Resistance Pattern
For Fluoroquinolone-Susceptible Pseudomonas UTI
Oral therapy options (when resistance <10%):
- Ciprofloxacin 500-750 mg twice daily for 7-10 days 4, 5
- Levofloxacin 750 mg once daily for 5-7 days 3, 6, 4
The fluoroquinolones remain highly effective for susceptible Pseudomonas UTI, with historical cure rates of 89% at early follow-up and 64% at one month. 5 However, do not use fluoroquinolones empirically if local resistance exceeds 10%, the patient used fluoroquinolones in the last 6 months, or the patient is from a urology department. 3, 6
For Multidrug-Resistant or Difficult-to-Treat Pseudomonas (DTR-PA)
First-line parenteral options:
- Ceftolozane/tazobactam 1.5 g IV every 8 hours 1, 3
- Ceftazidime/avibactam 2.5 g IV every 8 hours 1, 3
- Imipenem/cilastatin-relebactam 1.25 g IV every 6 hours 2, 3
- Cefiderocol 2 g IV every 8 hours 1, 3
These novel β-lactam/β-lactamase inhibitor combinations have emerged as the first reliable alternatives to polymyxin-based therapy for DTR-PA, with activity against >90% of MDR/XDR strains in some collections. 1 Ceftolozane/tazobactam and ceftazidime/avibactam are strongly recommended as first-line options with moderate certainty of evidence. 1
Alternative Options for Resistant Pseudomonas
Second-line parenteral agents:
- Ceftazidime 2 g IV every 8 hours 2, 7
- Cefepime 1-2 g IV every 12 hours 2, 7
- Piperacillin/tazobactam 2.5-4.5 g IV every 8 hours 2, 7
- Aminoglycosides: Gentamicin 5 mg/kg IV once daily or Amikacin 15 mg/kg IV once daily 2, 3, 7
- Colistin-based therapy (reserve for salvage situations) 1
Aminoglycosides are particularly recommended when there is prior fluoroquinolone resistance, though they require combination with another agent for complicated UTI. 3 Colistin should be avoided when possible due to high nephrotoxicity risk (50% acute kidney injury rate) and narrow therapeutic window. 1
Treatment Duration
Standard duration: 7-10 days for complicated UTI 2, 3, 4
Extend to 14 days if:
- Male patient (cannot exclude prostatitis) 2, 3, 6
- Delayed clinical response (not afebrile within 48 hours) 3, 6
- Underlying urological abnormalities 3, 6
- Immunocompromised status 6
Consider 7 days if:
- Hemodynamically stable and afebrile for ≥48 hours 2, 3
- Prompt symptom resolution 3
- No underlying urological abnormalities 6
Combination Therapy Considerations
Combination therapy is not routine but may be considered: 1
- For severe infections or sepsis
- Upon infectious diseases consultation
- Fosfomycin as companion agent is specifically mentioned for DTR-PA 1
- For documented or presumptive Pseudomonas in nosocomial pneumonia, combination with an anti-pseudomonal β-lactam is recommended 4
The evidence shows combination therapy should not be routine, with only conditional recommendation and low certainty of evidence. 1
Critical Monitoring and Pitfalls
Obtain urine culture before starting antibiotics to guide targeted therapy and monitor for resistance development. 2, 3, 4 Pseudomonas aeruginosa may develop resistance fairly rapidly during treatment, particularly when initial MIC is >0.5 mg/L. 4, 8
Reassess at 48-72 hours if no clinical improvement: 3, 6
- Adjust therapy based on culture results
- Consider imaging to rule out obstruction or abscess
- Evaluate for underlying urological abnormalities requiring intervention
Address underlying urological abnormalities: 2, 3
- Replace indwelling catheters that have been in place ≥2 weeks at treatment onset
- Remove catheters as soon as clinically appropriate
- Manage obstruction, foreign bodies, or incomplete voiding