Pyelonephritis is an infection in the urinary tract which normally begins within your bladder and move upstream to affect one or both kidneys. Infection usually is due to bacteria. It is often harder than an infection with a bladder only (cystitis). The bacterium can sometimes enter the blood stream, and then, especially after surgery, go into the kidneys.
Although many bacteria and viruses may lead to pyelonephritis, Escherichia coli bacterium is the common cause of pyelonephritis. Rarely, kidney infections cause serious health problems, but fast therapy can prevent most complications. Pyelonephritis can damage your kidney permanently or cause life threats by moving in your bloodstream. Treatment of kidney infections usually only needs antibiotics, but hospitalisation may be necessary in serious cases.