kidney infection is the most hard to treat infection of the urinary tract infection,here are some of the symtoms of kidney infection.
1)fever
2)loss of weight
3)pain in the lower back thats were your kidney is located.
Treatment is normally based on urine culture and scanning of the affected area to check obstruction or backward flow of urine which cause the infection to spread from bladder to the kidney.
it can it to pemanent kidney damge or order life treation illness.