Treatment for Pyelonephritis
For uncomplicated pyelonephritis in outpatients, oral ciprofloxacin 500 mg twice daily for 7 days is the first-line treatment when local fluoroquinolone resistance is below 10%, but if resistance exceeds 10%, give a single IV dose of ceftriaxone 1g first, then start oral fluoroquinolone therapy. 1
Initial Diagnostic Steps
Before starting any antibiotic therapy:
- Always obtain urine culture and susceptibility testing to guide definitive therapy and adjust treatment if the patient fails to respond 1
- This is the most critical step that is commonly missed in practice 1
Outpatient Treatment Algorithm
When Fluoroquinolone Resistance is <10%:
First-line options:
- Ciprofloxacin 500 mg orally twice daily for 7 days 1, 2
- Ciprofloxacin 1000 mg extended-release once daily for 7 days 1
- Levofloxacin 750 mg once daily for 5 days 1, 3
The 7-day ciprofloxacin regimen achieved 97% short-term clinical cure rates and 93% long-term efficacy in a high-quality randomized trial, demonstrating non-inferiority to 14-day treatment 2
When Fluoroquinolone Resistance is ≥10%:
- Give one IV dose of ceftriaxone 1g OR an aminoglycoside first 1
- Then start oral fluoroquinolone therapy 1
- This approach is critical because fluoroquinolone resistance rates have reached 48% for E. coli in some populations 4
Alternative Oral Therapy:
- Trimethoprim-sulfamethoxazole (TMP-SMX) 160/800 mg twice daily for 14 days - only if the pathogen is confirmed susceptible 1
- Oral β-lactams are less effective and should not be used as monotherapy without an initial parenteral dose 1
Inpatient Treatment
Indications for hospitalization: 5, 6
- Complicated infections
- Sepsis or severe illness
- Persistent vomiting preventing oral intake
- Failed outpatient treatment
- Extremes of age
- Suspected complications
IV antibiotic options: 1
- Fluoroquinolone (ciprofloxacin or levofloxacin)
- Aminoglycoside with or without ampicillin (gentamicin 5-7 mg/kg once daily) 1
- Extended-spectrum cephalosporin (ceftriaxone 1g every 12 hours) 4
- Extended-spectrum penicillin with or without aminoglycoside 1
- Carbapenem 1
Recent evidence shows ceftriaxone achieved 68.7% microbiological eradication versus only 21.4% with levofloxacin in a 2021 trial, reflecting rising fluoroquinolone resistance 4
Treatment Duration by Antibiotic Class
- Fluoroquinolones: 5-7 days depending on the specific agent 1
- TMP-SMX: 14 days 1
- β-lactams: 10-14 days 1
Microbiological Considerations
Most common pathogens: 1
- E. coli (75-95% of cases)
- Proteus mirabilis
- Klebsiella pneumoniae
Adjust therapy based on culture results - this is non-negotiable 1
Critical Pitfalls to Avoid
- Never start antibiotics without obtaining urine cultures first 1
- Do not ignore local resistance patterns when selecting empiric therapy 1
- Do not use fluoroquinolones empirically in areas with >10% resistance without adding an initial parenteral dose 1
- Do not use oral β-lactams as monotherapy without an initial parenteral dose 1
- Do not use inadequate treatment duration, especially with β-lactam agents 1
- In elderly patients, monitor closely for adverse effects, particularly with aminoglycosides and fluoroquinolones 1