Acute pyelonephritis

Last reviewed: May 2019

Last updated: October 2018

Summary

Common signs and symptoms include acute-onset fever, chills, severe back or flank pain, nausea and vomiting, and costovertebral angle tenderness.

Urinalysis and urine culture confirm the diagnosis of pyelonephritis. Urine cultures, obtained prior to treatment, demonstrate bacteria, most often Escherichia coli .

The route and choice of empiric antibiotics depend on the severity of illness and the presumed bacterial sensitivities pending culture results.

Complications most often result from inappropriate (wrong drug or wrong dose) antibiotic use or antibiotic resistance, leading to recurrent or progressive infection.

Other common causes of complications are inadequate treatment of anatomic abnormalities (e.g., kidney stones or obstruction), preventing bacterial clearance.

Definition

Pyelonephritis, from the Greek "pyelo" (pelvis), "nephros" (kidney), and "-itis" (inflammation), describes a severe infectious inflammatory disease of the renal parenchyma, calices, and pelvis that can be acute, recurrent, or chronic. Acute infections may be caused by enteric bacteria (e.g., Escherichia coli ) that ascend from the lower urinary tract or that spread hematogenously to the kidney. Most episodes are uncomplicated and are cured with no residual renal damage. Complicated infections can result from underlying medical problems (e.g., diabetes mellitus, HIV), genitourinary anatomic abnormalities, obstruction (e.g., benign prostatic hypertrophy, calculi), and/or multidrug-resistant pathogens. Urinary tract infection, or UTI, is a nonspecific term that refers to infection anywhere in the urinary tract, from the urethra to the bladder to the ureters to the kidneys. Pyelonephritis refers specifically to infections in the kidney.

History and exam

Key diagnostic factors

fever

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Other diagnostic factors

nausea and vomiting
dysuria, frequency, or urgency
flank pain or costovertebral angle tenderness

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Risk factors

frequent sexual intercourse
urinary tract infection
mother with urinary tract infection history
diabetes mellitus
stress incontinence
new sex partner
spermicide use
age between 18 and 50 years
age >60 years
foreign body in urinary tract (e.g., calculus, catheter)
anatomic/functional urinary abnormality
immunosuppressive state (e.g., HIV, transplantation, chemotherapy, corticosteroid use)
pregnancy

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Diagnostic investigations

1st investigations to order

urinalysis
Gram stain
urine culture
complete blood count
erythrocyte sedimentation rate
C-reactive protein
procalcitonin
blood culture

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Investigations to consider

99mTc-DMSA scintigraphy
contrast-enhanced spiral computed tomography
magnetic resonance imaging
renal ultrasound

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Emerging tests

interleukin
copeptin

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Treatment algorithm

INITIAL

Contributors

Authors VIEW ALL 

Lynda A. Frassetto, MD

Professor of Medicine

Division of Nephrology

University of California

San Francisco

Disclosures

LAF declares that she has no competing interests.

Acknowledgements

Dr Lynda A. Frassetto would like to gratefully acknowledge the assistance of Donna M. Frassetto. DMF declares that she has no competing interests.

Peer reviewers VIEW ALL 

John Lam, MD

Attending Urologist

Providence Saint Joseph Medical Center

Burbank

Assistant Clinical Professor of Urology

Department of Urology

David Geffen School of Medicine at UCLA

Los Angeles

Disclosures

JL declares that he has no competing interests.

Robert Mactier, MD, FRCP

Consultant Nephrologist/Lead Clinician

Renal Unit

Glasgow Royal Infirmary

NHS Greater Glasgow and Clyde

Glasgow

Disclosures

RM declares that he has no competing interests.

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Acute pyelonephritis

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic investigations

1st investigations to order

Investigations to consider

Emerging tests

Treatment algorithm

high index of suspicion with mild-to-moderate symptoms and uncomplicated disease

high index of suspicion with severe symptoms or complicated disease or pregnant patients

mild-to-moderate symptoms with uncomplicated disease

severe symptoms or complicated disease or pregnant patients

recurrent disease within 1 to 2 weeks

Contributors

Authors VIEW ALL 

Lynda A. Frassetto, MD

Disclosures

Acknowledgements

Peer reviewers VIEW ALL 

John Lam, MD

Disclosures

Robert Mactier, MD, FRCP

Disclosures

Differentials

Guidelines

Patient leaflets

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