What is the antibiotic of choice for uncomplicated pyelonephritis in women?

Antibiotic Treatment for Uncomplicated Pyelonephritis in Women

For uncomplicated pyelonephritis in women, oral ciprofloxacin (500 mg twice daily) for 7 days is the antibiotic of choice when local fluoroquinolone resistance rates are below 10%. 1

First-Line Treatment Options

Outpatient Management

• Fluoroquinolones (when local resistance <10%):

  • Ciprofloxacin 500 mg twice daily for 7 days 1
  • Ciprofloxacin 1000 mg extended-release once daily for 7 days 1
  • Levofloxacin 750 mg once daily for 5 days 1

• Initial parenteral dose recommended if fluoroquinolone resistance exceeds 10%:

  • Single dose of ceftriaxone 1 g IV 1
  • OR consolidated 24-hour dose of an aminoglycoside 1

Alternative When Susceptibility is Known

• Trimethoprim-sulfamethoxazole (TMP-SMX) 160/800 mg (double-strength) twice daily for 14 days 1
  • Only when the pathogen is known to be susceptible
  • If used empirically, should be preceded by a single IV dose of ceftriaxone 1 g 1

Treatment Algorithm Based on Local Resistance Patterns

1. Obtain urine culture and susceptibility testing before starting antibiotics 1

2. Assess local fluoroquinolone resistance rates:

   • If <10%: Start oral fluoroquinolone (ciprofloxacin or levofloxacin)
   • If >10%: Give initial IV dose of ceftriaxone 1 g, then oral fluoroquinolone

3. Adjust therapy based on culture results:

   • If susceptible to TMP-SMX: Can switch to TMP-SMX to complete treatment
   • If resistant to initial therapy: Change based on susceptibility results

Inpatient Treatment for Severe Cases

For women requiring hospitalization:

• IV antimicrobial options 1:
  • Fluoroquinolone (ciprofloxacin 400 mg twice daily or levofloxacin 750 mg once daily)
  • Extended-spectrum cephalosporin (ceftriaxone 1-2 g daily)
  • Aminoglycoside with or without ampicillin
  • Piperacillin/tazobactam (for more severe cases)

Important Considerations

• Oral β-lactams are less effective than fluoroquinolones or TMP-SMX for pyelonephritis and should be avoided if possible 1

• Duration of therapy:

  • Fluoroquinolones: 5-7 days 1, 2, 3
  • TMP-SMX: 14 days traditionally, though recent evidence suggests 7 days may be effective when the pathogen is susceptible 1, 4

• Microbiology: E. coli causes 75-95% of cases, with occasional other Enterobacteriaceae 1

• Resistance concerns: Fluoroquinolone resistance is increasing worldwide, with rates exceeding 10% in many regions 5, 6

Pitfalls to Avoid

1. Not obtaining cultures before starting antibiotics - always collect urine culture before initiating therapy 1

2. Using TMP-SMX empirically without knowing susceptibility - can lead to treatment failure due to high resistance rates 1

3. Using oral β-lactams as monotherapy - these have inferior efficacy compared to fluoroquinolones and TMP-SMX 1

4. Not considering local resistance patterns - treatment should be guided by local E. coli resistance data 1

5. Prolonged therapy when shorter courses are effective - 5-7 days of fluoroquinolones is sufficient for most cases, avoiding unnecessary antibiotic exposure 2, 3

The 2021 American College of Physicians guidelines and 2024 European Association of Urology guidelines both support the use of fluoroquinolones for 5-7 days as first-line therapy for uncomplicated pyelonephritis in women, with TMP-SMX as an alternative when susceptibility is confirmed 1.