Acute pyelonephritis in adults commonly presents as 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.
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.
Urinary tract infections in children is a specialized topic that is not covered here; please see the BMJ Best Practice topic: Urinary tract infections in children.
History and exam
Key diagnostic factors
Other diagnostic factors
- nausea and vomiting
- dysuria, frequency, or urgency
- flank pain or costovertebral angle tenderness
- urinary tract infection
- diabetes mellitus
- stress incontinence
- foreign body in urinary tract (e.g., calculus, catheter)
- anatomic/functional urinary abnormality
- immunosuppressive state (e.g., HIV, transplantation, chemotherapy, corticosteroid use)
- frequent sexual intercourse
- mother with urinary tract infection history
- new sex partner
- spermicide use
- age between 18 and 50 years
- age >60 years
1st investigations to order
- Gram stain
- urine culture
- complete blood count
- erythrocyte sedimentation rate
- C-reactive protein
- blood culture
Investigations to consider
- renal ultrasound
- contrast-enhanced spiral computed tomography
- magnetic resonance imaging
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
Lynda A. Frassetto, MD
Professor of Medicine
Division of Nephrology
University of California
LAF declares that she has no competing interests.
Dr Lynda A. Frassetto would like to gratefully acknowledge the assistance of Donna M. Frassetto. DMF declares that she has no competing interests.
John Lam, MD
Providence Saint Joseph Medical Center
Assistant Clinical Professor of Urology
Department of Urology
David Geffen School of Medicine at UCLA
JL declares that he has no competing interests.
Robert Mactier, MD, FRCP
Consultant Nephrologist/Lead Clinician
Glasgow Royal Infirmary
NHS Greater Glasgow and Clyde
RM declares that he has no competing interests.
- Chronic pyelonephritis
- Pelvic inflammatory disease
- Pelvic pain syndrome
- Appropriate Use of Short-Course Antibiotics in Common Infections: Best Practice Advice From the American College of Physicians
- EAU guidelines on urological infections
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