What is the recommended treatment for a urinary tract infection (UTI) caused by Pseudomonas in a patient with an allergy to quinolones?

Treatment of Pseudomonas UTI in a Patient with Quinolone Allergy

For a urinary tract infection caused by Pseudomonas aeruginosa in a patient with quinolone allergy, ceftazidime or a carbapenem (meropenem or imipenem) is the recommended first-line treatment. 1, 2

First-Line Treatment Options

• Ceftazidime: 2g IV every 8 hours is FDA-approved for Pseudomonas UTIs and provides excellent coverage without cross-reactivity with quinolone allergies 1
• Meropenem: 1g IV every 8 hours is highly effective against Pseudomonas and appropriate for patients with quinolone allergies 2
• Piperacillin-tazobactam: 3.375-4.5g IV every 6 hours is another effective option for susceptible Pseudomonas strains 3

Treatment Algorithm Based on Infection Severity

For Non-Severe UTI (outpatient management):

1. Fosfomycin IV: Recommended for complicated UTI without septic shock, with high certainty of evidence 4
2. Aminoglycosides: Consider for short-duration therapy in non-severe complicated UTI without septic shock 4

For Severe UTI (requiring hospitalization):

1. Ceftazidime: 2g IV every 8 hours 1
2. Meropenem: 1g IV every 8 hours 2
3. Cefepime: 1-2g IV every 12 hours (higher dose recommended) 4
4. Piperacillin-tazobactam: 2.5-4.5g IV every 8 hours 4

Special Considerations

• Combination therapy should be considered for critically ill patients with suspected Pseudomonas infection 3
• Recommended combination: Antipseudomonal β-lactam (ceftazidime, cefepime, piperacillin-tazobactam) + aminoglycoside (gentamicin or amikacin) 3
• Duration of therapy: 7-10 days for uncomplicated infections, 10-14 days for complicated or bloodstream infections 3

Treatment for Resistant Pseudomonas

• For difficult-to-treat resistant Pseudomonas, consider ceftolozane/tazobactam (1.5-3g IV q8h) or ceftazidime/avibactam (2.5g IV q8h) 3
• Alternative options include imipenem/cilastatin/relebactam or colistin-based therapy for highly resistant strains 3

Pitfalls and Caveats

• Avoid aminoglycoside monotherapy except for uncomplicated UTIs due to potential nephrotoxicity and ototoxicity 3, 4
• Monitor renal function closely when using aminoglycosides or high-dose β-lactams 4
• Consider local resistance patterns when selecting empiric therapy, as Pseudomonas resistance varies significantly by region 5, 6
• For patients who have received recent antibiotic therapy (within 90 days), consider using an alternative class of antibiotics to prevent resistance development 3

Stepdown Therapy

• Once the patient improves clinically and susceptibility results are available, consider oral options if available based on susceptibility testing 4
• For patients with persistent symptoms after 5-7 days of appropriate therapy, consider imaging to rule out complications such as abscess or obstruction 4