What is the recommended antibiotic regimen for a catheter-associated urinary tract infection (UTI) that is nitrite positive?

Treatment of Catheter-Associated UTI with Positive Nitrite Test

For catheter-associated urinary tract infections (CAUTI) with a positive nitrite test, the recommended first-line empirical treatment is an intravenous third-generation cephalosporin, amoxicillin plus an aminoglycoside, or a second-generation cephalosporin plus an aminoglycoside. 1

First-Line Empirical Treatment Options

• Intravenous third-generation cephalosporin (strongly recommended by European Association of Urology) 1
• Amoxicillin plus an aminoglycoside 1
• Second-generation cephalosporin plus an aminoglycoside 1

Rationale for Treatment Selection

• CAUTIs have a broader microbial spectrum than uncomplicated UTIs, with common pathogens including E. coli, Proteus spp., Klebsiella spp., Pseudomonas spp., Serratia spp., and Enterococcus spp. 1, 2
• A positive nitrite test has a high positive predictive value (96%) and specificity (94%), strongly suggesting the presence of nitrate-reducing bacteria 3
• Antimicrobial resistance is more likely in catheter-associated UTIs, necessitating broader spectrum initial therapy 1, 4

Treatment Duration

• 7 days if symptoms resolve promptly 1, 2
• 10-14 days for patients with delayed response 1, 2
• 14 days for male patients where prostatitis cannot be excluded 2

Catheter Management

• If the catheter has been in place for ≥2 weeks at the onset of UTI, it should be replaced to hasten resolution of symptoms and reduce the risk of subsequent infection 1, 2
• A urine specimen for culture should be obtained prior to initiating antimicrobial therapy due to the wide spectrum of potential infecting organisms and increased likelihood of antimicrobial resistance 5, 2

Alternative Treatment Options

• For oral step-down therapy after clinical improvement:

  • Nitrofurantoin (for uncomplicated UTIs due to susceptible organisms) 5, 1
  • Fosfomycin (for uncomplicated UTIs due to susceptible organisms) 5, 4
  • Fluoroquinolones (if local resistance rates are <10% and patient has not used fluoroquinolones in the last 6 months) 1, 6

• For multi-drug resistant organisms:

  • For ESBL-producing Enterobacterales: carbapenems, ceftazidime-avibactam, or ceftolozane-tazobactam 4
  • For carbapenem-resistant Enterobacterales (CRE): plazomicin, ceftazidime-avibactam, or polymyxin-based combination therapy 5, 4

Special Considerations

• Local antimicrobial resistance patterns should guide empirical therapy choices 1, 2
• Fluoroquinolone resistance is emerging, particularly in older patients, so these agents should be used judiciously 2, 3
• For patients with infections resistant to oral antibiotics, culture-directed parenteral antibiotics should be used for as short a course as reasonable 2

Common Pitfalls and Caveats

• Avoid empirical use of trimethoprim-sulfamethoxazole or ciprofloxacin in communities with high resistance rates 4
• Do not rely solely on urine dipstick tests in elderly patients, as specificity ranges from 20% to 70% 5
• Avoid treating asymptomatic bacteriuria in catheterized patients unless specific indications exist 5, 2
• CAUTIs are the leading cause of secondary healthcare-associated bacteremia, with approximately 20% of hospital-acquired bacteremias arising from the urinary tract 1