Acute Pyelonephritis in Adults: Rapid Evidence Review


Am Fam Physician. 2020 Aug 1;102(3):173-180.

  Patient information: A handout on this topic is available at

Author disclosure: No relevant financial affiliations.

Acute pyelonephritis is a bacterial infection of the kidney and renal pelvis and should be suspected in patients with flank pain and laboratory evidence of urinary tract infection. Urine culture with antimicrobial susceptibility testing should be performed in all patients and used to direct therapy. Imaging, blood cultures, and measurement of serum inflammatory markers should not be performed in uncomplicated cases. Outpatient management is appropriate in patients who have uncomplicated disease and can tolerate oral therapy. Extended emergency department or observation unit stays are an appropriate option for patients who initially warrant intravenous therapy. Fluoroquinolones and trimethoprim/sulfamethoxazole are effective oral antibiotics in most cases, but increasing resistance makes empiric use problematic. When local resistance to a chosen oral antibiotic likely exceeds 10%, one dose of a long-acting broad-spectrum parenteral antibiotic should also be given while awaiting susceptibility data. Patients admitted to the hospital should receive parenteral antibiotic therapy, and those with sepsis or risk of infection with a multidrug-resistant organism should receive antibiotics with activity against extended-spectrum beta-lactamase–producing organisms. Most patients respond to appropriate management within 48 to 72 hours, and those who do not should be evaluated with imaging and repeat cultures while alternative diagnoses are considered. In cases of concurrent urinary tract obstruction, referral for urgent decompression should be pursued. Pregnant patients with pyelonephritis are at significantly elevated risk of severe complications and should be admitted and treated initially with parenteral therapy.

Acute pyelonephritis, a serious and relatively common bacterial infection of the kidney and renal pelvis, accounts for approximately 250,000 office visits and 200,000 hospital admissions annually in the United States.13



As of 2014, Escherichia coli resistance to trimethoprim/sulfamethoxazole and fluoroquinolones in the United States exceeded 35% and 10%, respectively.

A systematic review of 8 randomized controlled trials (N = 2,515) demonstrated equivalent clinical success rates in treating uncomplicated acute pyelonephritis with a 5- to 7-day course of fluoroquinolones compared with a 14-day course.

In the male subgroup of a 2017 randomized controlled trial, a 7-day course of ciprofloxacin was inferior to a 14-day course with respect to short-term cure rates with no differences in long-term outcomes.

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Clinical recommendationEvidence ratingComments

Urine culture and antimicrobial susceptibility testing should be performed in patients with suspected acute pyelonephritis and used to direct antibiotic therapy.7


Expert consensus guideline in the absence of clinical trials

Initial imaging should not be performed in uncomplicated cases of acute pyelonephritis. Contrast-enhanced computed tomography of the abdomen and pelvis is indicated in septic patients, when urinary obstruction is suspected, or when patients do not respond to appropriate therapy within 48 to 72 hours.23


Expert consensus guideline based on low-quality observational evidence

Fluoroquinolones (e.g., ciprofloxacin for 7 days or levofloxacin [Levaquin] for 5 days) and trimethoprim/sulfamethoxazole for 14 days are appropriate first-line oral antibiotic therapies for uncomplicated acute pyelonephritis in women when the causative organism is susceptible.7,30


Expert consensus based on consistent evidence from randomized controlled trials demonstrating effectiveness

In locations where Escherichia coli resistance to empiric oral therapy is likely greater than 10%, an initial broad-spectrum, long-acting parenteral antibiotic such as ceftriaxone, ertapenem (Invanz), or an aminoglycoside should be given concurrently.7


Expert consensus based on lower quality clinical trials demonstrating benefit when combined with beta-lactams

Patients at increased risk of infection with multidrug-resistant organisms and those with sepsis should be treated with parenteral antibiotics that have activity against extended-spectrum beta-lactamase–producing organisms until susceptibility data are available.7


Expert consensus guideline in the absence of clinical trials

A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, go to

The Authors

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JOEL HERNESS, MD, is a faculty member of the Family Medicine Residency Program at Mike O'Callaghan Military Medical Center, Nellis Air Force Base, Nev., and an assistant professor in the Department of Family Medicine at the Uniformed Services University of the Health Sciences, Bethesda, Md....

AMELIA BUTTOLPH, MD, is the associate program director of the Camp Lejeune (N.C.) Family Medicine Residency Program and an assistant professor in the Department of Family Medicine at the Uniformed Services University of the Health Sciences.

NOA C. HAMMER, MD, MPH, is the program director of the Naval Hospital Camp Pendleton (Calif.) Family Medicine Residency Program and an assistant professor in the Department of Family Medicine at the Uniformed Services University of the Health Sciences.

Address correspondence to Joel Herness, MD, Mike O'Callaghan Military Medical Center, Family Medicine Residency, 4700 Las Vegas Blvd. N., Nellis AFB, NV 89191 (email: Reprints are not available from the authors.

Author disclosure: No relevant financial affiliations.


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