what is the cause of pyelonephritis
There are several types of acute nephritis: In interstitial nephritis, the spaces between the kidney tubules become inflamed. This inflammation causes the kidneys to swell. Pyelonephritis is an inflammation of the kidney, usually due to a bacterial infection. In the majority of cases, the infection starts within the bladder and then migrates up the ureters and into the kidneys. Ureters are two tubes that transport urine from each kidney to the bladder.