What is the recommended treatment for pyelonephritis?

Treatment for Pyelonephritis

For uncomplicated pyelonephritis in outpatients, oral ciprofloxacin 500 mg twice daily for 7 days (or levofloxacin 750 mg daily for 5 days) is the first-line treatment when local fluoroquinolone resistance is below 10%; if resistance exceeds 10%, give one dose of IV ceftriaxone 1g before starting oral fluoroquinolone therapy. 1

Initial Assessment

Before starting any antibiotics, you must obtain urine culture and susceptibility testing in all patients with suspected pyelonephritis 1. This is critical because:

• It guides definitive therapy adjustments 1
• Resistance patterns are increasingly problematic, with E. coli resistance to fluoroquinolones reaching 10-18% in many areas 2
• Failing to obtain cultures before antibiotics is a common and avoidable error 1

Outpatient Treatment Algorithm

When Fluoroquinolone Resistance is <10%:

First-line options:

• Ciprofloxacin 500 mg PO twice daily for 7 days 1
• Ciprofloxacin 1000 mg extended-release PO daily for 7 days 1
• Levofloxacin 750 mg PO daily for 5 days 1, 3

When Fluoroquinolone Resistance is ≥10%:

• Give one dose of ceftriaxone 1g IV or an aminoglycoside IV first 1
• Then start oral fluoroquinolone therapy as above 1
• This approach addresses the resistance concern while maintaining outpatient management 4

Alternative Oral Therapy:

Trimethoprim-sulfamethoxazole (TMP-SMX) 160/800 mg (double-strength) twice daily for 14 days can be used ONLY if the organism is proven susceptible 1. Do not use this empirically due to high resistance rates 5, 6.

Oral β-lactams should not be used as monotherapy without an initial parenteral dose due to inferior efficacy 1. If used, they require 10-14 days of treatment 1.

Inpatient Treatment

Hospitalization is indicated for:

• Severe illness or sepsis 4
• Inability to tolerate oral medications 6
• Suspected complications 5
• Extremes of age 6
• Failed outpatient treatment 6

Initial IV Antibiotic Options:

Choose based on local resistance patterns 1:

• Fluoroquinolone (levofloxacin 750 mg IV daily) 1
• Aminoglycoside (gentamicin 5-7 mg/kg once daily) with or without ampicillin 1
• Extended-spectrum cephalosporin (ceftriaxone 1g IV every 12-24 hours) 1
• Extended-spectrum penicillin with or without aminoglycoside 1
• Carbapenem (for suspected extended-spectrum beta-lactamase producers) 1

Transition to Oral Therapy:

Once the patient improves clinically (typically 48-72 hours), switch to oral antibiotics based on susceptibility results 4. Complete the full treatment duration with combined IV and oral therapy.

Treatment Duration by Antibiotic Class

• Fluoroquinolones: 5-7 days total 1
• TMP-SMX: 14 days 1
• β-lactams: 10-14 days 1

The longer duration for β-lactams reflects their lower efficacy compared to fluoroquinolones 1.

Special Populations

Elderly patients: Monitor closely for adverse effects, particularly nephrotoxicity with aminoglycosides and neuropsychiatric effects with fluoroquinolones 1.

Pregnant patients: Require hospitalization and initial parenteral therapy due to significantly elevated risk of severe complications 4.

Common Causative Organisms

E. coli accounts for 75-95% of cases, with occasional Proteus mirabilis and Klebsiella pneumoniae 1, 5, 6.

Critical Pitfalls to Avoid

• Never skip urine cultures before starting antibiotics 1
• Do not ignore local resistance patterns when selecting empiric therapy 1
• Do not use fluoroquinolones empirically in areas with >10% resistance without adding initial parenteral therapy 1
• Do not use oral β-lactams alone without an initial parenteral dose 1
• Always adjust therapy based on culture results 1
• Do not undertreate with inadequate duration, especially with β-lactams 1

Follow-up

Repeat urine culture 1-2 weeks after completing antibiotics 6. If the patient does not improve within 48-72 hours, obtain imaging (contrast-enhanced CT) and repeat cultures while considering alternative diagnoses or complications 5, 4.