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[pyelo- + nephritis]
Inflammation of the kidney and renal pelvis, usually due to a bacterial infection that has ascended from the urinary bladder.
SYN: SEE: tubulointerstitial nephritis

Escherichia coli is usually the agent. Cultures of urine and blood are obtained to guide therapy.

This condition is characterized by the sudden onset of chills and fever with dull pain in the flank over one or both kidneys. There is tenderness when the costovertebral angle is palpated or percussed. There may be signs of cystitis, i.e., urgency with burning, and frequency of urination. Urinalysis and culture findings include pyuria, urine sediment with leukocytes singly, in clumps, or in casts, significant bacteria (more than 100,000 organisms/μL of urine), low specific gravity and osmolarity, slightly alkaline urine pH, and sometimes proteinuria, glycosuria, and ketonuria.

Antibiotics, e.g., fluoroquinolones, sulfa drugs, cephalosporins, or aminoglycosides, that effectively treat common pathogens of the urinary tract are administered, pending the results of cultures. Antiemetics are given to control nausea and vomiting. If patients are unable to take medications by mouth or if they have predisposing conditions, e.g., pregnancy or diabetes, that increase the likelihood of a bad outcome, they may be admitted to the hospital for observation, monitoring, and hydration.

The outcome depends on the character and virulence of the infection, accessory etiological factors, drainage of the kidney, presence or absence of complications, and general physical condition of the patient.

Antibiotics and antipyretics are administered as prescribed. The patient is encouraged to complete the full course of antibiotics and drink 2 to 3 L of fluids per day to prevent urinary stasis and to flush by-products of the inflammatory process. Symptoms may disappear after a few days of treatment, and urine becomes sterile within 48 to 72 hr; however, the prescribed course of therapy should be completed (10 to 14 days). The patient is taught how to correctly collect a midstream urine specimen, and urine usually is recultured about 1 week after therapy has concluded. After the completion of therapy, the patient may require urine cultures periodically over the next year to detect recurrent or residual infections. The patient should report any signs of infection during scheduled follow-up care. Patients requiring prolonged use of indwelling catheters are at increased risk for recurring infections. Strict aseptic technique should be carried out during insertion and care. Females can help to prevent urinary tract infections by wiping the perineum from front to back after defecation and by washing the area before and after sexual intercourse. Chronic pyelonephritis is a persistent kidney inflammation that may scar the kidneys and lead to chronic renal failure. Its cause may be bacterial, metastatic, or urogenous and is most common in patients with histories of urinary obstructions or vesicoureteral reflux. Hypertension occurs in late stages of this condition, and effective treatment involves controlling blood pressure, surgically eliminating obstructions and/or correcting anomalies, and treating bacterial infections with long-term antimicrobial therapy.

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