Pyelonephritis

Bacterial infection of the kidney. Pyelonephritis can be acute (sudden) or chronic (slow, subtle, and stubborn). It is most often due to the ascent of bacteria from the bladder up the ureters to infect the kidneys. The symptoms of pyelonephritis include flank (side) pain, fever, shaking chills, sometimes foul-smelling urine, urgency (to urinate), frequency (urinating), and general malaise. Tenderness is elicited on gently tapping over the kidney with a fist (percussion). The laboratory examination of the urine (the urinalysis) reveals white blood cells (pyuria, i.e. pus in the urine) and bacteria in the urine (bacteriuria). There is usually also an increase in circulating white cells in the blood (leucocytosis). Treatment involves appropriate antibiotics.

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Inflammation of the renal parenchyma, calices, and pelvis, particularly due to local bacterial infection. [pyelo- + G. nephros, kidney, + -itis, inflammation]

- acute p. acute inflammation of the renal parenchyma and pelvis characterized by small cortical abscesses and yellowish streaks in the medulla due to pus in the collecting tubules and interstitial tissue.

- ascending p. p. due to bacterial infection from the lower urinary tract, particularly by reflux of infected urine.

- chronic p. chronic inflammation of the renal parenchyma and pelvis resulting from bacterial infection, characterized by calyceal deformities and overlying large flat renal scars with patchy distribution.

- xanthogranulomatous p. a chronic inflammatory condition diffusely involving the entire kidney and usually resulting in a grossly enlarged and functionless kidney that can grossly resemble a neoplasm or tuberculosis; histologically, it is characterized by an inflammatory reaction with numerous lipid-laden, foamy histiocytes mixed with lymphocytes and plasma cells to form multiple granulomas.

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py·elo·ne·phri·tis .pī-(ə-)lō-ni-'frīt-əs n, pl -phrit·i·des -'frit-ə-.dēz inflammation of both the parenchyma of a kidney and the lining of its renal pelvis esp. due to bacterial infection

py·elo·ne·phrit·ic -'frit-ik adj

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n.

bacterial infection of the kidney substance. In acute pyelonephritis, the patient has pain in the loins, a high temperature, and shivering fits. Treatment is by the administration of an appropriate antibiotic, and a full urological investigation is conducted to determine any underlying abnormality and prevent recurrence. In chronic pyelonephritis, the kidneys become small and scarred and kidney failure ensues. vesicoureteric reflux in childhood is one of the causes.

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py·elo·ne·phri·tis (pi″ə-lo-nə-friґtis) [pyelo- + nephr- + -itis] inflammation of the kidney and renal pelvis because of bacterial infection; it begins in the interstitial tissues (interstitial nephritis) and rapidly extends to involve the tubules (tubulointerstitial nephritis), glomeruli (glomerulonephritis), and then the renal blood vessels.