What antibiotics are used to treat pyelonephritis?

Antibiotic Treatment for Pyelonephritis

Oral fluoroquinolones are the first-line treatment for uncomplicated pyelonephritis in outpatients where local resistance rates are <10%, with options including ciprofloxacin 500-750 mg twice daily for 7 days or levofloxacin 750 mg once daily for 5 days. 1, 2

Initial Assessment and Antibiotic Selection

• Always obtain urine culture and susceptibility testing before initiating therapy to guide definitive treatment 1, 2
• Initial empiric therapy should be tailored based on local resistance patterns and subsequently adjusted according to culture results 1
• The most common causative organism is Escherichia coli (75-95%), followed by other Enterobacteriaceae such as Proteus mirabilis and Klebsiella pneumoniae 1, 3

Outpatient Treatment Options

First-line options:

• Fluoroquinolones (in areas with <10% resistance):
  • Ciprofloxacin 500 mg twice daily for 7 days 1, 2
  • Ciprofloxacin 1000 mg extended-release for 7 days 1
  • Levofloxacin 750 mg once daily for 5 days 1, 2, 4

When fluoroquinolone resistance exceeds 10%:

• Add an initial one-time IV dose of a long-acting parenteral antimicrobial (ceftriaxone 1g or an aminoglycoside) before starting oral therapy 1, 2
• Trimethoprim-Sulfamethoxazole (TMP-SMX) 160/800 mg twice daily for 14 days is appropriate only if the uropathogen is known to be susceptible 1, 2

Inpatient Treatment Options

• For patients requiring hospitalization, initial IV antimicrobial regimens include:
  • Fluoroquinolones 1, 2
  • Aminoglycosides with or without ampicillin 1
  • Extended-spectrum cephalosporins (e.g., ceftriaxone 1g every 12 hours) 1, 5
  • Extended-spectrum penicillins with or without aminoglycosides 1
  • Carbapenems 1, 2

Treatment Duration

• Fluoroquinolones: 5-7 days depending on the specific agent 1, 2, 6
• TMP-SMX: 14 days 1, 2
• β-lactams (including cephalosporins): 10-14 days 1, 2

Special Considerations

Elderly patients:

• Monitor closely for adverse effects, particularly with aminoglycosides and fluoroquinolones 1
• Dose adjustment may be required for moderate renal impairment 2

Oral β-lactams:

• Less effective than fluoroquinolones for treating pyelonephritis 2
• If used, should be preceded by an initial IV dose of a long-acting parenteral antimicrobial (e.g., ceftriaxone 1g) 2
• Treatment duration of 10-14 days 1, 2

Common Pitfalls to Avoid

• Failing to obtain urine cultures before initiating antibiotics 1, 2
• Not considering local resistance patterns when selecting empiric therapy 1, 2, 6
• Using fluoroquinolones empirically in areas with >10% resistance without adding an initial dose of a parenteral agent 1, 2
• Using oral β-lactams as monotherapy without an initial parenteral dose 1, 2
• Not adjusting therapy based on culture results 1, 2
• Inadequate treatment duration, especially with β-lactam agents 1
• Using agents like nitrofurantoin or oral fosfomycin, which are not recommended for pyelonephritis due to insufficient efficacy data 2

Step-Down Therapy

• Once the patient improves clinically and can tolerate oral intake, switch to appropriate oral therapy based on culture results 2
• Oral β-lactams can be used for step-down therapy if the pathogen is susceptible, but they are generally less effective than other available agents 1