Clinical manifestations; diagnosis; and treatment of acute pyelonephritis, UpToDate 2009

Acute pyelonephritis is a urinary tract infection that has progressed from the lower urinary tract to the upper urinary tract. Most episodes of acute pyelonephritis are uncomplicated but hospitalization may be required [1].
Acute uncomplicated pyelonephritis typically occurs in healthy, young women and must be distinguished from acute complicated pyelonephritis and from chronic pyelonephritis:
Acute complicated pyelonephritis is progression of upper urinary tract infection to emphysematous pyelonephritis, renal corticomedullary abscess, perinephric abscess, or papillary necrosis. (See 'Acute complicated pyelonephritis' below.)
Chronic pyelonephritis is an uncommon cause of chronic tubulointerstitial disease due to recurrent infection, such as infection in association with a chronically obstructing kidney stone (possibly producing xanthogranulomatous pyelonephritis) or vesicoureteral reflux. Affected patients can present with weeks to months of insidious symptoms. (See "Xanthogranulomatous pyelonephritis" and "Presentation, diagnosis, and clinical course of vesicoureteral reflux".)
The clinical features, diagnosis, and treatment of acute uncomplicated and complicated pyelonephritis will be reviewed here. The microbiology and pathogenesis of acute pyelonephritis are discussed separately. (See "Microbiology and pathogenesis of acute pyelonephritis".)... Authorized only