What is the best course of treatment for a patient with a urinary tract infection (UTI), presenting with fever, flank pain, and nausea, who is due for stent removal in six days and has urinalysis results showing leukocytosis (leukocytes), nitrites, and bacteriuria (bacteria)?

Management of UTI in a Patient with Indwelling Ureteral Stent

This patient requires immediate empiric broad-spectrum antibiotic therapy for catheter-associated pyelonephritis, with levofloxacin 750 mg once daily being the preferred first-line agent, and the stent should be replaced at the time of removal in six days if it has been in place for ≥2 weeks. 1

Immediate Management Steps

Obtain Cultures Before Antibiotics

• Collect a urine culture specimen immediately prior to initiating antimicrobial therapy, as stent-associated infections have a wide spectrum of potential organisms with increased likelihood of antimicrobial resistance 1
• The sensitivity of urine culture alone for detecting stent colonization is only 40%, meaning a negative urine culture does not rule out a colonized stent 2
• In patients with indwelling stents, 60% of those with positive stent cultures have sterile urine cultures, highlighting the discordance between urine and stent bacteriology 2

Clinical Diagnosis

This patient has pyelonephritis (not simple cystitis) based on:

• Fever with flank pain indicating upper tract involvement 3
• Systemic symptoms (nausea) suggesting kidney infection 4
• Urinalysis showing significant pyuria (75 leukocytes/µL), bacteriuria, and hematuria 5
• Positive nitrites, which are highly specific for bacterial infection, particularly in the context of symptoms 5

Antibiotic Selection

First-Line Empiric Therapy

Levofloxacin 750 mg once daily is the recommended first-line agent for this patient with mild-to-moderate catheter-associated UTI who is not severely ill 1. This recommendation is based on:

• Superior microbiologic eradication rates compared to other regimens 1
• Excellent tissue penetration for pyelonephritis 3
• Once-daily dosing improving compliance 1

Alternative Regimens

If the patient appears severely ill or has risk factors for multidrug resistance:

• Use combination therapy with amoxicillin plus an aminoglycoside 4
• Or a second-generation cephalosporin plus an aminoglycoside 4
• Or an intravenous third-generation cephalosporin 4, 3

Avoid These Agents

• Do not use moxifloxacin due to uncertainty regarding effective urinary concentrations 1
• Avoid ciprofloxacin for empirical treatment if the patient has used fluoroquinolones in the last 6 months or has been in a urology department, due to high resistance rates 1
• Do not use nitrofurantoin for pyelonephritis, as it does not achieve adequate tissue levels in the kidney parenchyma 3

Stent Management Strategy

Timing of Stent Removal

• Proceed with planned stent removal in six days as scheduled 4
• If the stent has been in place for ≥2 weeks, replace it at the time of removal to hasten symptom resolution and reduce risk of subsequent infection 1
• Collect urine culture from the freshly placed catheter if feasible, as biofilm on older catheters may not accurately reflect true bladder infection status 1

Why Stent Replacement Matters

• Stent colonization occurs in 42% of patients with indwelling stents 2
• Bacteria on colonized stents are significantly more resistant to antibiotics than organisms isolated before stent insertion 2
• Patients with positive stent cultures have 5.7 times higher odds of developing clinical UTI within 12 months compared to those with negative cultures 6

Antibiotic Duration

Standard Duration

Treat for 7 days if the patient shows prompt resolution of symptoms 1. This applies to:

• Defervescence within 48-72 hours 4
• Resolution of flank pain 3
• Clinical improvement in overall condition 1

Extended Duration

Extend treatment to 10-14 days if there is delayed response, regardless of whether the catheter remains in place 1. Indicators for extended therapy include:

• Persistent fever beyond 72 hours 4
• Continued flank pain or systemic symptoms 3
• Lack of clinical improvement 1

Adjusting Therapy Based on Culture Results

When Results Return

• Modify antibiotics based on culture and susceptibility results when available 1
• The most common isolates from stent-associated infections are E. coli, Enterococcus spp., Staphylococcus spp., Pseudomonas, and Candida spp. 2, 7
• Stent isolates demonstrate higher resistance rates than pre-stent urine cultures 2

If No Clinical Improvement by 72 Hours

• Consider extending treatment duration 1
• Perform urologic evaluation to assess for complications such as obstruction or abscess 1
• Obtain repeat imaging if indicated 4

Special Considerations for This Patient

Risk Factors Present

This patient has several factors increasing infection risk:

• Indwelling stent in place (duration unknown, but removal planned suggests >1 week) 2
• Positive nitrites indicating gram-negative bacteria, likely E. coli 5, 7
• Upper tract involvement (pyelonephritis) increasing risk of complications 3

Common Pitfalls to Avoid

• Do not delay catheter replacement if the stent has been in place for ≥2 weeks, as this is crucial for treatment success 1
• Do not rely solely on urine culture to guide therapy, as 60% of colonized stents have negative urine cultures 2
• Do not treat asymptomatic bacteriuria if discovered incidentally, but this patient is clearly symptomatic 4
• Do not use short-course (3-day) therapy for pyelonephritis, even though it may be appropriate for simple cystitis 1, 3

Monitoring Response

• Expect defervescence within 48-72 hours of appropriate antibiotic therapy 4
• Resolution of flank pain should occur within several days 3
• If fever persists beyond 72 hours, consider imaging to evaluate for complications such as perinephric abscess or obstruction 4

Prophylaxis Considerations

At Time of Stent Removal

• No routine antimicrobial prophylaxis is recommended for simple cystoscopic stent removal in asymptomatic patients 4
• However, this patient is symptomatic and requires therapeutic (not prophylactic) antibiotics 1
• Continue therapeutic antibiotics through the stent removal procedure 4

Post-Removal

• Complete the full 7-14 day course of antibiotics even after stent removal 1
• No additional prophylaxis is needed after completing the therapeutic course unless recurrent infections develop 4