What antibiotics (abx) to start for a patient with a urinary tract infection (UTI) and suspected kidney stone?

Antibiotic Treatment for UTI with Suspected Kidney Stone

For a patient with UTI and suspected kidney stone, start empiric treatment with a combination of amoxicillin plus an aminoglycoside, a second-generation cephalosporin plus an aminoglycoside, or an intravenous third-generation cephalosporin. 1

Initial Antibiotic Selection Algorithm

Step 1: Assess for Systemic Symptoms

• If patient has systemic symptoms (fever, rigors, altered mental status), use combination therapy with:
  • Amoxicillin plus an aminoglycoside OR
  • Second-generation cephalosporin plus an aminoglycoside OR
  • IV third-generation cephalosporin 1

Step 2: If No Systemic Symptoms, Consider Oral Options

• Obtain urine culture before starting antibiotics 1
• Avoid fluoroquinolones (ciprofloxacin, levofloxacin) for empiric treatment if:
  • Local resistance rates are ≥10%
  • Patient has used fluoroquinolones in the past 6 months 1
• Consider nitrofurantoin for uncomplicated lower UTI without kidney involvement 1
  • Note: Nitrofurantoin has lower likelihood of persistent resistance (20.2% at 3 months) compared to other antibiotics 1

Step 3: Duration of Treatment

• 7 days for patients with prompt symptom resolution 1
• 10-14 days for those with delayed response 1
• If using levofloxacin (after culture results), 5-day regimen (750mg once daily) may be considered for non-severely ill patients 1, 2

Special Considerations for Kidney Stones

Infection Stones

• Removal of suspected infection stones or infected stone fragments is recommended to prevent:
  • Further stone growth
  • Recurrent UTI
  • Renal damage 1

Antibiotic Prophylaxis for Stone Procedures

• Antimicrobial prophylaxis should be administered prior to stone intervention based on:
  • Prior urine culture results
  • Local antibiogram
  • Best practice guidelines 1
• A single oral or IV dose of an antibiotic covering gram-positive and gram-negative uropathogens is recommended before procedures 1

Management of Purulent Urine

• If purulent urine is encountered during stone removal:
  • Abort the procedure
  • Establish appropriate drainage (ureteral stent or nephrostomy tube)
  • Continue broad-spectrum antibiotics
  • Obtain urine culture 1
• Resume procedure once infection is appropriately treated 1

Common Pitfalls to Avoid

• Pitfall #1: Using fluoroquinolones as first-line therapy

  • Fluoroquinolones should be reserved for situations where other first-line agents cannot be used 1, 2
  • FDA advisory warns against using fluoroquinolones for uncomplicated UTIs due to unfavorable risk-benefit ratio 1

• Pitfall #2: Not obtaining urine culture before starting antibiotics

  • Always obtain urine specimen for culture prior to initiating antimicrobial therapy due to wide spectrum of potential infecting organisms and increased likelihood of antimicrobial resistance 1

• Pitfall #3: Not replacing indwelling catheters before treatment

  • If an indwelling catheter has been in place for ≥2 weeks at onset of UTI, replace it to hasten symptom resolution and reduce risk of subsequent bacteriuria and UTI 1

• Pitfall #4: Treating asymptomatic bacteriuria

  • Treatment of asymptomatic bacteriuria increases risk of symptomatic infection, bacterial resistance, and healthcare costs 1

• Pitfall #5: Using unnecessarily long antibiotic courses

  • Longer courses or greater potency antibiotics are not needed in patients with recurrent UTI and may be associated with more recurrences due to loss of protective periurethral and vaginal microbiota 1