From the Guidelines

The duration of treatment for pyelonephritis is typically 7-14 days, but short-course therapy of 5-7 days may be effective in some cases.

The choice of treatment duration depends on the severity of illness, local resistance patterns, and specific host factors, such as allergies 1.
Current guidelines recommend 7-14 days of antibiotic therapy for women with pyelonephritis, but do not comment on men due to a lack of data 1.
Studies have shown that short-duration therapy (5-7 days) can result in similar clinical success as long-duration therapy (10-14 days) for complicated UTIs, including pyelonephritis 1.
Fluoroquinolones and cephalosporins are recommended for oral empiric treatment of uncomplicated pyelonephritis, while other agents such as nitrofurantoin and oral fosfomycin should be avoided due to insufficient data on their efficacy 1.
The IDSA/ESCMID guideline recommends either an oral fluoroquinolone for 7 days or TMP-SMX for 14 days for treatment of patients with pyelonephritis not requiring hospitalization 1.

Oral fluoroquinolones (e.g., ciprofloxacin, levofloxacin) for 5-7 days may be effective for mild to moderate pyelonephritis 1.
TMP-SMX for 14 days may be considered, but its use is limited due to high rates of resistance and corresponding failure rates 1.
Intravenous antimicrobial regimens (e.g., fluoroquinolones, aminoglycosides, extended-spectrum cephalosporins) may be necessary for patients with severe illness or complicated UTIs 1.

From the Research

The duration of treatment for pyelonephritis is a topic of ongoing debate, with various studies suggesting different treatment lengths.

A study published in 2017 2 found that 5 days of fluoroquinolone treatment was non-inferior to 10 days of treatment for acute uncomplicated pyelonephritis.
Another study published in 2021 3 compared short-course and long-course antibiotic therapy in pyelonephritis and found that short-course treatment was at least as effective as long-course treatment for both microbiological and clinical success.
A retrospective observational study published in 2020 4 found that short-course antibiotic therapy (6-9 days) was as effective as prolonged-course therapy (10 or more days) for children with pyelonephritis.
A study published in 2017 5 found that a 7-day course of TMP-SMX may be as effective as a 7-day course of ciprofloxacin for the treatment of pyelonephritis.
A systematic review and meta-analysis published in 2013 6 found that 7 days of treatment for acute pyelonephritis was equivalent to longer treatment in terms of clinical failure and microbiological failure.

The optimal duration of antibiotic treatment for pyelonephritis may vary depending on the patient population and the specific antibiotic used.

The study published in 2017 2 found that the efficacy of 5 days of fluoroquinolone treatment did not seem different from 10 days of treatment for acute uncomplicated pyelonephritis.
The study published in 2020 4 found that short-course antibiotic therapy may be as effective as prolonged-courses for children with pyelonephritis.
The study published in 2013 6 found that 7 days of treatment for acute pyelonephritis was equivalent to longer treatment in terms of clinical failure and microbiological failure, except in patients with urogenital abnormalities, where longer treatment may be required.

The findings of these studies have important clinical implications for the treatment of pyelonephritis.

The use of shorter treatment courses may help reduce the risk of antibiotic resistance and minimize the side effects of antibiotic therapy 3, 4.
The choice of antibiotic and treatment duration should be individualized based on the patient's specific needs and medical history 2, 5.
Further studies are needed to confirm the findings of these studies and to determine the optimal treatment duration for different patient populations 3, 4.