Lower back pain and kidney pain are classic symptoms of kidney infection, including the serious kidney infection known as pyelonephritis, according to WebMD. Other symptoms experienced with pyelonephritis include fever or chills, confusion, nausea and vomiting. The condition also causes urinary changes, including pain with urination, foul-smelling or cloudy urine, blood in the urine and increased urgency or frequency of urination.
Most infections of the urinary tract do not move to the kidneys, notes WebMD. Instead, UTIs generally infect the urethra and bladder. However, when an infection moves into the kidneys and ureters, which make up the upper urinary system, pyelonephritis can result. It occurs when bacteria enter the body and travel up the urethra into the bladder before escaping there and moving into the kidneys.
Because of the anatomical structure of the female urethra, more women than men contract kidney infections, and women are also more prone to UTIs. Infections can involve one or both kidneys. Kidney infection can be potentially serious and cause severe illness, especially if the infection moves into the blood. Most women notice pain or discomfort when urinating as a first symptom of the condition. Antibiotics are usually highly successful in treating kidney infections, however.