What is an infection in the lining of kidney?

An infection in the lining of the kidney is called pyelonephritis. It is a type of urinary tract infection (UTI) that affects the kidneys and can cause severe pain in the back, sides, and lower abdomen. It can also cause fever, chills, and difficulty urinating. Pyelonephritis is typically caused by bacteria, such as Escherichia coli (E. coli), that enter the urethra and travel up the urinary tract to the kidneys. It is more common in women than in men, and it can be more severe in people with diabetes or a weakened immune system. Treatment for pyelonephritis usually involves antibiotics to kill the bacteria causing the infection, pain relievers and fluids to stay hydrated. In severe cases, hospitalization may be necessary.