What is the best treatment for a patient with a UTI due to a gram-negative organism, with upcoming surgery, and urinalysis showing leukocytes esterase trace and calcium oxalate moderate?

Treatment of Preoperative UTI with Gram-Negative Organism

This patient requires immediate antibiotic treatment with a full therapeutic course (not prophylaxis) before proceeding to surgery, as the urine culture shows 10,000 CFU/mL of a single gram-negative organism with trace leukocyte esterase indicating symptomatic bacteriuria. 1

Immediate Management Decision

• Do not proceed with surgery until completing antibiotic treatment, as untreated UTI before urologic procedures resulted in 5.6% post-operative infectious complications versus minimal rates in treated patients 1
• The presence of 10,000 CFU/mL with leukocyte esterase (even trace) indicates active infection requiring full therapeutic treatment, not single-dose prophylaxis 1
• Postoperative UTI significantly increases surgical site infection risk (OR 3.1,95% CI 1.6-6.1) 2

Antibiotic Selection Based on Susceptibilities

First-line empiric therapy while awaiting final susceptibilities:

• Nitrofurantoin (if susceptibilities confirm sensitivity) - resistance rates <6% for gram-negative organisms 3
• Trimethoprim-sulfamethoxazole is FDA-approved for UTI caused by E. coli and other Enterobacteriaceae 4, though resistance varies 15-50% across Europe 3
• Fluoroquinolones (ciprofloxacin/levofloxacin) are alternatives if nitrofurantoin cannot be used 1, but avoid if possible as they increase multidrug-resistant bacteria risk (46% vs 22% resistance rates) 2
• Ceftriaxone is an alternative for gram-negative UTI 1

Treatment Duration

Complete a full 7-day therapeutic course before surgery 1:

• Short-course therapy (1-2 doses) is only appropriate for asymptomatic bacteriuria immediately before endoscopic procedures, not for symptomatic UTI or procedures days away 1
• The 7-day course ensures bacterial eradication before surgery 1
• Single-dose prophylaxis is inadequate for this clinical scenario with documented infection 1

If Surgery Cannot Be Delayed

If surgery is urgent and cannot wait for treatment completion:

• Administer antimicrobial prophylaxis 30-60 minutes before the procedure using an agent active against the cultured organism 1
• Continue therapeutic antibiotics postoperatively for the full course 5
• This is suboptimal compared to completing treatment pre-operatively 1

Perioperative Antibiotic Management

Standard prophylaxis timing and duration:

• Single-dose prophylaxis should be given within 60 minutes of surgical incision 5
• Antimicrobial prophylaxis should be discontinued within 24 hours after wound closure in most cases 5
• Exception: If source control is adequate and infection signs are present, short-course therapy (3-5 days) with early re-evaluation is recommended 5

Critical Pitfalls to Avoid

• Do not use extended prophylaxis regimens - patients receiving extended prophylaxis have 2.8 times higher risk of lower UTI and 3.1 times higher risk of multidrug-resistant bacteria compared to standard prophylaxis 6
• Avoid fluoroquinolones when possible - their use for UTI increases subsequent fluoroquinolone resistance in surgical site infections 2
• Do not treat asymptomatic bacteriuria differently - the presence of symptoms (leukocyte esterase) mandates full treatment 5
• Resistance threshold: When empiric resistance exceeds 20%, alternative antibiotic regimens should be considered 3

Postoperative Catheter Management

If indwelling catheter remains postoperatively:

• Consider culture-directed therapy 24-48 hours before catheter removal 5
• Alternatively, administer empiric antimicrobials at catheter removal, especially in patients with risk factors 5
• Catheter-associated bacteriuria occurs at 5-10% per day of catheterization 5