Antibiotic Therapy for Complicated UTI with Indwelling Catheter
Replace the indwelling catheter before initiating antibiotics if it has been in place for ≥2 weeks, then start empiric therapy with intravenous third-generation cephalosporin (ceftriaxone 1-2 g daily or cefepime 1-2 g twice daily), or amoxicillin plus an aminoglycoside, or a second-generation cephalosporin plus an aminoglycoside for 7-14 days. 1, 2
Critical First Step: Catheter Replacement
Catheter replacement must occur before starting antibiotics if the catheter has been in place ≥2 weeks. 1 This intervention:
- Significantly decreases polymicrobial bacteriuria and shortens time to clinical improvement 1
- Lowers CA-UTI recurrence rates within 28 days (3 versus 11 patients with symptomatic relapse, p = 0.015) 1
- Addresses biofilm formation on internal and external catheter surfaces that protect uropathogens from antimicrobials and host immune response 3, 4
Obtain urine culture from the new catheter before starting antibiotics to guide targeted therapy, as CA-UTIs have broader microbial spectrum including E. coli, Proteus, Klebsiella, Pseudomonas, Serratia, and Enterococcus species with higher antimicrobial resistance rates. 5, 2
When to Treat: Symptomatic CA-UTI Only
Treat only symptomatic CA-UTI, never asymptomatic bacteriuria (except in pregnant women or patients undergoing urologic procedures with anticipated mucosal bleeding). 1, 2
Symptoms requiring treatment include: 2, 1
- New onset or worsening fever, rigors, altered mental status
- Flank pain or costovertebral angle tenderness
- Acute hematuria
- Pelvic discomfort, suprapubic pain or tenderness
- Dysuria or urgent/frequent urination (in those whose catheter has been removed)
Empiric Antibiotic Selection
First-Line Options for Moderate to Severe CA-UTI:
Intravenous third-generation cephalosporin: 2, 1, 5
- Ceftriaxone 1-2 g IV daily, OR
- Cefepime 1-2 g IV twice daily
Alternative first-line combinations: 2, 1, 5
- Amoxicillin plus an aminoglycoside (gentamicin 1 mg/kg after dialysis for dialysis patients, or standard dosing)
- Second-generation cephalosporin plus an aminoglycoside
Fluoroquinolone Considerations:
Use ciprofloxacin (500-750 mg PO q12h or 400 mg IV q8-12h) ONLY if: 2, 6, 7
- Local resistance rate is <10%, AND
- Patient has NOT used fluoroquinolones in the last 6 months, AND
- Patient is NOT from a urology department
Do not use fluoroquinolones empirically in urology department patients or those with recent fluoroquinolone exposure due to resistance rates exceeding 10%. 2, 1
For mild to moderate CA-UTI where oral therapy is appropriate, levofloxacin 750 mg orally once daily demonstrates superior microbiologic eradication rates specifically validated for CA-UTI. 1
Treatment Duration
Standard duration is 7 days for patients with prompt symptom resolution (hemodynamically stable and afebrile for ≥48 hours). 2, 1, 5
Extend to 10-14 days for: 2, 1, 5
- Patients with delayed response
- Male patients when prostatitis cannot be excluded (14 days mandatory)
- Patients with persistent underlying urological abnormalities
Treatment duration should be closely related to management of any underlying urological abnormality. 2
Tailoring Therapy After Culture Results
Once susceptibility results are available: 2, 1
Switch to oral step-down therapy after clinical improvement with susceptible organisms: 5
- Nitrofurantoin (for uncomplicated UTIs due to susceptible organisms)
- Fosfomycin
- Fluoroquinolones (if resistance <10% and no recent use)
For multidrug-resistant organisms: 5, 8
- Carbapenem-resistant Enterobacterales (CRE): Plazomicin, ceftazidime-avibactam, or polymyxin-based combination therapy
- ESBL-producing organisms: Carbapenems (meropenem/vaborbactam, imipenem/cilastatin-relebactam), ceftazidime-avibactam, or ceftolozane-tazobactam
Common Pitfalls to Avoid
Do not delay catheter replacement if it has been in place ≥2 weeks – this is crucial for treatment success and must be done before starting antibiotics. 1
Do not administer prophylactic antimicrobials routinely at catheter placement, removal, or replacement – this promotes antimicrobial resistance without preventing CA-UTI. 2, 3
Do not treat asymptomatic bacteriuria in catheterized patients – this increases antimicrobial resistance without preventing symptomatic CA-UTI. 2, 1, 3
Do not use routine periodic catheter changes to prevent infection – this practice lacks evidence-based support. 3
Recognize that CA-UTIs are the leading cause of secondary healthcare-associated bacteremia (approximately 20% of hospital-acquired bacteremias), with mortality of approximately 10%. 2, 5