Acute Pyelonephritis Lecture Notes

Definition

• Pyelo-: Pelvis
• Neph-: Kidney
• -itis: Inflammation
• Acute Pyelonephritis: Inflammation of the kidney, typically due to bacterial infection.

Urinary Tract Infection (UTI)

• Upper Urinary Tract: Kidney and ureters
• Lower Urinary Tract: Bladder and urethra
• Acute Pyelonephritis is an upper urinary tract infection.

Causes

• Ascending infection from lower UTI:
  • Bacteria colonizing urethra and bladder ascend to the kidney via ureter.
  • Common organisms: E. coli, Proteus species, Enterobacter species.
• Hematogenous infection (less common):
  • Spread through bloodstream due to septicemia, bacteremia, or infective endocarditis.
  • Common organisms: Staphylococcus species, E. coli.

Risk Factors

• Female sex
• Sexual intercourse
• Indwelling catheters
• Diabetes mellitus
• Urinary tract obstruction
• Vesicoureteral reflux (VUR):
  • Urine moves backward due to vesicoureteral orifice failure.
  • Causes: Congenital defect or bladder outlet obstruction.

Pathophysiology

• Typically unilateral infection
• Bacteria adhere to renal epithelium, triggering inflammation.
• Neutrophil response:
  • Chemokines attract neutrophils.
  • Neutrophils infiltrate renal interstitium but spare the glomeruli and vessels.
  • White blood cells excreted in urine; can form "casts" in the shape of tubules.

Symptoms

• White blood cells in urine
• Leukocytosis
• Systemic symptoms: Fevers, chills, nausea, vomiting
• Flank pain at costovertebral angle
• Symptoms help distinguish from lower UTI.

Treatment

• Antibiotics
• Ensure adequate hydration
• Complications: Potential for renal abscess formation, chronic pyelonephritis, papillary necrosis.

Recap

• Acute pyelonephritis is bacterial infection of upper urinary tract.
• Usually stems from lower UTI, especially with VUR.
• Systemic symptoms include fevers and flank pain.
• Treated with antibiotics.

Conclusion

• Acute pyelonephritis is a serious condition requiring prompt treatment to prevent complications.
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