What causes kidney infections in a child?

Pyelonephritis: An infection of the kidney (pyelonephritis) results in severe back pain, high fever and nausea/vomiting. Unlike an infection only involving the bladder, the ascension of bacteria into the kidney is a dangerous event. In children it should raise the possibility of an abnormality of the urinary system. Congenital obstruction or urinary reflux are the most common causes. Surgery may be necessary.