Treatment of Pyelonephritis
For outpatient treatment of acute uncomplicated pyelonephritis, oral ciprofloxacin 500 mg twice daily for 7 days is the preferred first-line therapy in areas where fluoroquinolone resistance is below 10%. 1, 2
Initial Diagnostic Steps
- Always obtain urine culture and susceptibility testing before initiating antibiotics to guide definitive therapy and adjust empirical treatment based on results 1, 2
- Blood cultures should be reserved for patients with uncertain diagnosis, immunocompromised status, or suspected hematogenous infection 3
Outpatient Treatment Regimens
First-Line Fluoroquinolone Options (when local resistance <10%)
- Ciprofloxacin 500 mg orally twice daily for 7 days is the standard regimen, with or without an initial 400 mg IV dose 1, 2
- Alternative once-daily fluoroquinolones include:
When Fluoroquinolone Resistance Exceeds 10%
- Administer one initial dose of a long-acting parenteral antibiotic before starting oral fluoroquinolone therapy 1, 2
- Parenteral options include:
Alternative Oral Regimen
- Trimethoprim-sulfamethoxazole 160/800 mg (double-strength) orally twice daily for 14 days is appropriate only if the uropathogen is known to be susceptible 1, 2
- If using TMP-SMX empirically when susceptibility is unknown, give an initial dose of ceftriaxone 1 g IV or aminoglycoside first 1
- High resistance rates (often >50%) make TMP-SMX inappropriate for empirical therapy 1, 5
Inpatient Treatment Regimens
Indications for Hospitalization
- Complicated infections, sepsis, persistent vomiting, failed outpatient treatment, extremes of age, or pregnancy 3, 6
Initial IV Antibiotic Options
- Fluoroquinolone (ciprofloxacin 400 mg IV every 12 hours or levofloxacin 750 mg IV daily) 2, 3
- Aminoglycoside with or without ampicillin 2, 3
- Extended-spectrum cephalosporin (ceftriaxone 1-2 g IV daily) 2, 3
- Extended-spectrum penicillin with or without aminoglycoside 2
- Carbapenem for suspected extended-spectrum beta-lactamase (ESBL) producers or multidrug-resistant organisms 2, 6
Transition to Oral Therapy
- Switch to oral antibiotics when clinically improved (typically within 48-72 hours) and able to tolerate oral intake 3, 6
- Oral β-lactams are less effective than fluoroquinolones but can be used if the pathogen is susceptible 2
Treatment Duration
- Fluoroquinolones: 5-7 days depending on the specific agent (levofloxacin 750 mg for 5 days, ciprofloxacin for 7 days) 1, 2, 7
- Trimethoprim-sulfamethoxazole: 14 days 1, 2
- β-lactams: 10-14 days 2
Follow-Up and Treatment Failure
- Repeat urine culture 1-2 weeks after completion of antibiotic therapy 3
- Most patients respond within 48-72 hours; lack of response warrants repeat cultures, imaging studies, and consideration of alternative diagnoses 3, 6
- Treatment failure may indicate resistant organisms, anatomic/functional abnormalities, or immunosuppression 3
Critical Pitfalls to Avoid
- Do not use oral β-lactams (amoxicillin, ampicillin, cephalexin) for empirical therapy due to high resistance rates and inferior efficacy 1
- Do not use fluoroquinolones empirically in areas with >10% resistance without adding an initial parenteral dose 1, 2
- Do not fail to obtain urine cultures before starting antibiotics, as this prevents appropriate tailoring of therapy 1, 2
- Do not use TMP-SMX empirically given widespread resistance (often 48-55% for E. coli) 5
- Do not undertreated with β-lactams—ensure adequate duration of 10-14 days if used 2
- Do not forget to adjust therapy based on culture results once susceptibility data are available 1, 2
Special Considerations
- Pregnant patients with pyelonephritis require hospital admission and initial parenteral therapy due to elevated risk of severe complications 6
- In elderly patients, monitor closely for adverse effects, particularly with aminoglycosides and fluoroquinolones 2
- The most common pathogen is Escherichia coli (75-95%), followed by Klebsiella pneumoniae and Proteus mirabilis 2, 3