This document discusses pyelonephritis, an ascending urinary tract infection that reaches the kidney. It defines pyelonephritis and classifies it as either acute or chronic. Acute pyelonephritis develops suddenly and can be severe in vulnerable groups. It involves inflammation of the kidney interstitium and tubule destruction. Chronic pyelonephritis results from repeated infections and scarring over time. Xanthogranulomatous pyelonephritis is an unusual chronic form characterized by granulomatous abscesses and severe kidney damage. Diagnosis involves urinalysis, urine culture and antibiotic sensitivity testing. Treatment focuses on controlling the infection with appropriate antibiotics based on culture results. Prevention prioritizes