Pyelonephritis and nephritis are two completely different concepts. Pyelonephritis is actually a bacterial inflammation, usually caused by bacteria at the urethral opening ascending into the urinary system and causing inflammation in areas like the renal pelvis and calyces. Patients may experience symptoms such as fever, hematuria, and back pain. In severe cases, it can cause necrosis of the renal papillae, leading to acute renal failure. Some patients may also develop perinephric abscesses, which are caused by bacterial infections. Nephritis, on the other hand, refers to inflammation within the glomeruli. This type of inflammation does not involve bacteria and is related to disorders in the body’s immune function. The disordered immune response is aggressive, attacking the glomerular filtration barrier, leading to proteinuria and hematuria. Therefore, the mechanisms of disease and treatment methods for the two conditions are different.