What are the antibiotics of choice for treating pyelonephritis?

Antibiotics of Choice for Pyelonephritis

For treating pyelonephritis, oral ciprofloxacin (500 mg twice daily) for 7 days, with or without an initial 400-mg dose of intravenous ciprofloxacin, is the first-line treatment in areas where fluoroquinolone resistance is <10%. 1

Outpatient Treatment Options

First-line options (non-hospitalized patients):

1. Fluoroquinolones:

   • Ciprofloxacin 500 mg PO twice daily for 7 days 1
   • Ciprofloxacin 1000 mg extended-release PO once daily for 7 days 1
   • Levofloxacin 750 mg PO once daily for 5 days 1, 2
   • Note: Only use when local fluoroquinolone resistance rates are <10% 1

2. When fluoroquinolone resistance is >10%:

   • Initial IV dose of ceftriaxone 1g OR
   • Consolidated 24-hour dose of an aminoglycoside
   • FOLLOWED BY oral fluoroquinolone therapy 1

3. Trimethoprim-sulfamethoxazole:

   • 160/800 mg (double-strength tablet) twice daily for 14 days
   • Only when the pathogen is known to be susceptible 1
   • If susceptibility unknown, give initial IV dose of ceftriaxone 1g or aminoglycoside 1

4. Oral β-lactams:

   • Less effective than other options for pyelonephritis 1
   • Require longer treatment duration (10-14 days) 1
   • Should be accompanied by initial IV dose of ceftriaxone 1g or aminoglycoside 1

Inpatient Treatment Options

For patients requiring hospitalization:

• Intravenous fluoroquinolone
• Aminoglycoside (with or without ampicillin)
• Extended-spectrum cephalosporin or extended-spectrum penicillin (with or without aminoglycoside)
• Carbapenem 1

Key Principles of Treatment

1. Always obtain urine culture and susceptibility testing before starting therapy 1
2. Tailor therapy based on culture results when available 1
3. Consider local resistance patterns when selecting empiric therapy 1, 3
4. Duration of therapy:
   • Fluoroquinolones: 5-7 days 1, 2, 4
   • Trimethoprim-sulfamethoxazole: 14 days 1
   • β-lactams: 10-14 days 1

Important Considerations

• Recent studies show 7-day ciprofloxacin treatment is as effective as 14-day regimens with fewer side effects 4
• Levofloxacin 750 mg daily for 5 days has shown similar efficacy to longer regimens 2
• E. coli is the most common pathogen (75-95% of cases) 1
• Resistance rates vary geographically; local antibiograms should guide therapy 1, 3
• Some regions show increasing resistance to fluoroquinolones and trimethoprim-sulfamethoxazole 3, 5, 6

Common Pitfalls to Avoid

1. Not obtaining cultures before starting antibiotics - always collect specimens first 1
2. Ignoring local resistance patterns - treatment failure is more likely when empiric therapy doesn't match local resistance patterns 3, 5
3. Using fluoroquinolones when resistance exceeds 10% without adding an initial dose of ceftriaxone or aminoglycoside 1
4. Using trimethoprim-sulfamethoxazole empirically without knowing susceptibility - resistance rates can be high 1, 6
5. Treating for too long - shorter courses (5-7 days) of fluoroquinolones are effective and reduce risk of resistance development 4
6. Using broad-spectrum antibiotics unnecessarily - reserve these for serious infections to prevent further resistance development 3

The treatment algorithm should be guided by local resistance patterns, patient factors (allergies, comorbidities), and culture results when available, with fluoroquinolones remaining the mainstay of therapy in areas with low resistance rates.