What is the pathophysiology of acute pyelonephritis (kidney infection)?

Updated: Jul 01, 2021
  • Author: Tibor Fulop, MD, PhD, FACP, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Acute pyelonephritis results from bacterial invasion of the renal parenchyma. Bacteria usually reach the kidney by ascending from the lower urinary tract. [6] In all age groups, episodes of bacteriuria occur commonly, but most are asymptomatic and do not lead to infection. The development of infection is influenced by bacterial factors and host factors. [7]

Bacteria may also reach the kidney via the bloodstream. Hematogenous sources of gram-positive organisms, such as Staphylococcus, are intravenous drug abuse and endocarditis. Experimental evidence suggests that hematogenous spread of gram-negative organisms to the kidney is less likely unless an underlying problem exists, such as an obstruction. Little or no evidence supports lymphatic spread of uropathogens to the kidney.

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