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- A syndrome caused by infection of the renal parenchyma and/or renal pelvis, often producing localized flank/back pain combined with systemic symptoms, such as fever, chills, and nausea; wide spectrum from mild illness to septic shock
- Chronic pyelonephritis is the result of progressive inflammation of the renal interstitium and tubules, due to recurrent infection, vesicoureteral reflux, or both.
- Pyelonephritis is considered uncomplicated if the infection is caused by a typical pathogen in an immunocompetent patient with normal urinary tract anatomy and renal function.
- System(s) affected: renal; urologic
- Synonym: acute upper urinary tract infection (UTI)
- May present as altered mental status; absence of fever is common in this age group.
- Elderly patients with diabetes and pyelonephritis are at higher risk of bacteremia, longer hospitalization, and mortality.
- The high prevalence of asymptomatic bacteriuria in the elderly makes the use of urine dipstick less reliable for diagnosing UTI in this population (1)[A].
- Most common medical complication requiring hospitalization
- Affects 1–2% of all pregnancies. Morbidity does not differ between trimesters.
- Urine culture for test of cure 1 to 2 weeks after therapy
- UTI is present in ~5% of patients age 2 months to 2 years with fever and no apparent source on history and physical exam.
- Treatment (PO or IV; inpatient or outpatient) should be based on the clinical situation and patient toxicity.
Community-acquired acute pyelonephritis: 28/10,000/year
Adult cases: 250,000/year, with 200,000 hospitalizations
Etiology and Pathophysiology
- Escherichia coli (>80%)
- Other gram-negative pathogens: Proteus, Klebsiella, Serratia, Clostridium, Pseudomonas, and Enterobacter
- Staphylococcus: Staphylococcus epidermidis, Staphylococcus saprophyticus (number 2 cause in young women), and Staphylococcus aureus
- Underlying urinary tract abnormalities
- Indwelling catheter/recent urinary tract instrumentation
- Immunocompromised, including diabetes
- Elderly, institutionalized patients (particularly women)
- Prostatic enlargement
- Childhood UTI
- Acute pyelonephritis within the prior year
- Frequent recent sexual intercourse; spermicide use; new sex partner within the prior year
- Stress incontinence in the previous 30 days
- Hospital-acquired infection
- Symptoms >7 days at time of presentation
Commonly Associated Conditions
- Indwelling catheters
- Renal calculi
- Benign prostatic hyperplasia