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- Acute pyelonephritis is a syndrome caused by an infection of the renal parenchyma and renal pelvis, often producing localized flank/back pain combined with systemic symptoms, such as fever, chills, and nausea. It has a wide spectrum of presentation, from mild illness to septic shock.
- Chronic pyelonephritis is the result of progressive inflammation of the renal interstitium and tubules, presumed to be caused by recurrent infection, vesicoureteral reflux, or both.
- Uncomplicated vs. complicated: Presentation is considered uncomplicated if the infection is caused by a typical pathogen in an immunocompetent patient who has normal urinary tract anatomy and renal function.
- System(s) affected: Renal; Urologic
- Synonym: Acute upper urinary tract infection (UTI)
- May present only as confusion; absence of fever is common in this age group.
- Elderly patients with diabetes and pyelonephritis are at higher risk of bacteremia, long hospitalization, and mortality.
- Most common medical complication requiring hospitalization
- Affects 1–2% of all pregnancies. Morbidity does not differ between trimesters.
- Urine culture follow-up 1–2 weeks after therapy
- UTI is present in ~5% of patients age 2 months to 2 years with fever and no source evident from history and physical exam.
- Route for antibiotics and location of care should be based on the clinical situation.
Community-acquired acute pyelonephritis: 28/10,000/year
Adult cases: 250,000/year, with 100,000 hospitalizations
- Underlying urinary tract abnormalities
- Indwelling catheter/recent urinary tract instrumentation
- Immunocompromise, including diabetes
- Elderly, institutionalized women
- Prostatic enlargement
- Childhood UTI
- Acute pyelonephritis within the prior year
- Frequency of recent sexual intercourse/spermicide use
- Stress incontinence
- Hospital-acquired infection
- Symptoms >7 days at presentation
- Infection with Escherichia coli (>80%)
- Other gram-negative pathogens: Proteus, Klebsiella, Serratia, Clostridium, Pseudomonas, and Enterobacter
- Staphylococcus: S. epidermis, S. saprophyticus (number 2 cause in young women), and S. aureus
Commonly Associated Conditions
- Indwelling catheters
- Renal calculi
- Benign prostatic hyperplasia