What is the first-line treatment for a complicated Urinary Tract Infection (UTI) with a possible kidney stone?

First-Line Treatment for Complicated UTI with Possible Kidney Stone

For a complicated UTI with a possible kidney stone, initiate empiric intravenous antibiotic therapy with a fluoroquinolone (ciprofloxacin 400 mg IV q12h or levofloxacin 750 mg IV q24h), an extended-spectrum cephalosporin (ceftriaxone 1-2 g IV q24h or cefepime 1-2 g IV q12h), or piperacillin-tazobactam (2.5-4.5 g IV q8h), based on local resistance patterns, while simultaneously obtaining urine culture and assessing for urinary obstruction. 1

Immediate Management Priorities

Assess for Obstruction and Sepsis

• A kidney stone causing urinary obstruction with concurrent infection constitutes a urologic emergency requiring immediate drainage. 1 If purulent urine or signs of obstructive pyelonephritis are present, establish drainage via ureteral stent or nephrostomy tube before definitive stone treatment. 1
• The presence of obstruction at any site in the urinary tract is a defining factor that makes this a complicated UTI. 1

Obtain Cultures Before Antibiotics

• Always obtain urine culture and susceptibility testing before initiating empiric therapy. 1 This is mandatory in complicated UTIs as the microbial spectrum is broader (E. coli, Proteus, Klebsiella, Pseudomonas, Serratia, Enterococcus) and antimicrobial resistance is more likely than in uncomplicated infections. 1

Empiric Antibiotic Selection

First-Line IV Options (Choose Based on Local Antibiogram)

The 2024 European Association of Urology guidelines provide specific dosing regimens: 1

Fluoroquinolones:

• Ciprofloxacin 400 mg IV q12h 1
• Levofloxacin 750 mg IV q24h 1

Extended-Spectrum Cephalosporins:

• Ceftriaxone 1-2 g IV q24h (higher dose recommended) 1
• Cefepime 1-2 g IV q12h (higher dose recommended) 1

Extended-Spectrum Penicillins:

• Piperacillin-tazobactam 2.5-4.5 g IV q8h 1

Aminoglycosides (with or without ampicillin):

• Gentamicin 5 mg/kg IV q24h 1
• Amikacin 15 mg/kg IV q24h 1

Reserve Carbapenems for Resistant Organisms

Carbapenems and novel broad-spectrum agents should only be used when early culture results indicate multidrug-resistant organisms. 1 Options include:

• Imipenem-cilastatin 0.5 g IV q8h 1
• Meropenem 1 g IV q8h 1
• Ceftolozane-tazobactam 1.5 g IV q8h 1
• Ceftazidime-avibactam 2.5 g IV q8h 1

Treatment Duration and Transition

Duration of Therapy

• Treat for 7-14 days depending on clinical response and underlying abnormality. 1 For males, use 14 days when prostatitis cannot be excluded. 1
• Treatment duration should be closely related to management of the underlying urological abnormality (in this case, the kidney stone). 1

Transition to Oral Therapy

• Once the patient is hemodynamically stable and afebrile, tailor therapy based on culture results and transition to oral antibiotics. 1
• Oral options after IV therapy include ciprofloxacin 500-750 mg PO q12h or levofloxacin 750 mg PO q24h, depending on susceptibilities. 1, 2

Stone Management Considerations

Timing of Stone Intervention

• Do not attempt stone removal in the presence of active infection with purulent urine. 1 If purulence is encountered, abort the procedure, establish drainage, continue broad-spectrum antibiotics, and obtain culture. 1
• Stone removal can proceed once infection is adequately treated. 1

Infection Stones

• If the stone is suspected to be an infection stone (struvite/carbonate apatite from urease-producing bacteria), complete stone removal is mandatory to prevent recurrence, as antibiotics alone cannot eradicate infection stones. 3, 4, 5 These stones harbor bacteria within their matrix and serve as a nidus for persistent infection. 3, 4, 5

Antimicrobial Prophylaxis for Stone Procedures

• Administer antimicrobial prophylaxis within 60 minutes prior to ureteroscopy or percutaneous nephrolithotomy based on prior culture results and local antibiogram. 1 A single dose covering gram-positive and gram-negative uropathogens is recommended. 1

Critical Pitfalls to Avoid

Do Not Use Fluoroquinolones Indiscriminately

• While fluoroquinolones are effective first-line agents for complicated UTI, avoid using them if local resistance exceeds 10%. 1 The FDA has issued warnings about serious adverse effects, and they should not be used for uncomplicated UTIs. 1
• Fluoroquinolones and cephalosporins cause more collateral damage to fecal microbiota than other antibiotic classes. 1

Do Not Delay Drainage in Obstructive Pyelonephritis

• Obstructive pyelonephritis is a urologic emergency that can rapidly progress to sepsis and death. 3 Antibiotics alone are insufficient without relieving obstruction. 3

Do Not Treat Asymptomatic Bacteriuria

• If the patient becomes asymptomatic during treatment, do not perform surveillance cultures or treat asymptomatic bacteriuria. 1 This increases resistance and recurrence risk. 1

Optimize Management of Underlying Abnormality

• Appropriate management of the urological abnormality (the kidney stone) is mandatory for successful treatment of complicated UTI. 1 Antibiotics alone without addressing the stone will likely result in treatment failure or recurrence. 1