How do you treat a urinary tract infection (UTI) caused by Pseudomonas aeruginosa?

Treatment of Urinary Tract Infections Caused by Pseudomonas aeruginosa

For urinary tract infections caused by Pseudomonas aeruginosa, treatment should include an antipseudomonal β-lactam (such as ceftazidime, cefepime, or a carbapenem) plus either an aminoglycoside or a fluoroquinolone, with therapy guided by culture and susceptibility testing. 1, 2

Initial Assessment and Diagnosis

• Obtain urine culture and susceptibility testing before initiating therapy
• Consider whether the UTI is complicated or uncomplicated
  • P. aeruginosa UTIs are typically considered complicated UTIs
  • Common risk factors for P. aeruginosa UTI include:
    • Indwelling urinary catheters (66.7% develop fever vs 40.5% without catheters) 3
    • Prior antibiotic use (strongest independent risk factor, OR 21.6) 4
    • Male sex (OR 2.61) 5
    • Steroid therapy (OR 2.40) 5
    • Bedridden functional status (OR 1.79) 5
    • Anatomical modifications of the urinary tract (OR 2.01) 5

Empiric Treatment Options

First-line Combination Therapy (preferred):

1. Antipseudomonal β-lactam plus aminoglycoside:

   • Piperacillin-tazobactam (3.375g or 4.5g IV q6h) + amikacin (15-20mg/kg IV q24h) 2
   • Ceftazidime (2g IV q8h) + tobramycin (5-7mg/kg IV q24h) 2
   • Meropenem (1g IV q8h) + amikacin (15-20mg/kg IV q24h) 2, 6

2. Antipseudomonal β-lactam plus fluoroquinolone:

   • Cefepime (2g IV q8-12h) + ciprofloxacin (400mg IV q12h or 750mg PO q12h) 2
   • Meropenem (1g IV q8h) + ciprofloxacin (400mg IV q12h) 2, 6

Alternative for Less Severe Infections:

• Oral ciprofloxacin (500mg BID) if susceptible and for outpatient treatment 2, 7
  • Note: Ciprofloxacin has shown 89% clearance of P. aeruginosa from urine during therapy, though recurrence rates increase at one month follow-up 8

Treatment Duration

• For complicated UTIs: 7-14 days of therapy is recommended 1
• Duration may need to be extended if there are complicating factors such as:
  • Urinary obstruction
  • Anatomical abnormalities
  • Immunosuppression

Adjusting Therapy Based on Culture Results

• Once culture and susceptibility results are available, narrow therapy to the most appropriate single agent if possible
• For multidrug-resistant P. aeruginosa (MDR-PA):
  • Continue combination therapy with two agents showing in vitro activity
  • Consider ceftolozane-tazobactam if susceptible 2

Management of Urinary Catheters

• Remove or replace indwelling catheters if present, as they significantly increase risk of treatment failure
• If catheter removal is not possible, consider changing the catheter before initiating antimicrobial therapy

Special Considerations

• Resistance patterns: Local resistance patterns should guide empiric therapy

  • P. aeruginosa resistance rates can be significant: fluoroquinolones (44.3%), antipseudomonal cephalosporins (36.1%), aminoglycosides (30.9%), carbapenems (28.8%) 5
  • MDR rate approximately 28.8% 5

• Therapeutic drug monitoring: Consider for aminoglycosides

  • Target peak levels: 15-20 μg/mL for tobramycin
  • Target trough levels: <2 μg/mL 2

Follow-up

• Repeat urine culture after completion of therapy to confirm eradication
• Higher readmission rates have been observed with P. aeruginosa UTIs (23.7% vs 15.8% for other pathogens) 5

Common Pitfalls to Avoid

• Monotherapy for severe P. aeruginosa infections may lead to treatment failure and emergence of resistance
• Inadequate duration of therapy increases risk of recurrence
• Failure to address underlying anatomical or functional abnormalities of the urinary tract
• Not considering local resistance patterns when selecting empiric therapy

By following this structured approach to treating P. aeruginosa UTIs, you can optimize outcomes while minimizing the risk of treatment failure and antimicrobial resistance.