Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at December 15, 2016

Pyelonephritis is the medical term for a type of UTI (urinary tract infection) that usually starts in the urethra or bladder then ascends upwards and spreads into the kidneys. Kidney infection is a serious condition on its own because the harmful bacteria can spread beyond the organs and into the bloodstream, causing a systemic infection. If treated incorrectly or left untreated, pyelonephritis can cause scarring or other permanent damage to the kidneys. Therefore, diagnosis and treatment should begin as quickly as possible.


Definition & Facts

The kidneys function to keep the balance of minerals and salts in the blood, to clean and purify the blood, and to help control blood pressure. When the body develops pyelonephritis, fluids and waste products can build up in the body, making the kidneys unable to function properly.

Pyelonephritis requires proper medical attention and treatment with specific antibiotics; if advanced, it may require bed rest or hospitalization so that fluids and antibiotics can be administered intravenously. When common kidney infection symptoms are accompanied by vomiting, nausea, or bloody urine, immediate medical attention is required. If left untreated, diseased kidneys can stop working completely, creating a potentially fatal problem. 

Symptoms & Complaints

Kidney infections are often accompanied by the following symptoms:


The most common cause of pyelonephritis is the bacterium, Escherichia coli which, like other bacteria and viruses, either moves up to the kidneys from the bladder or is carried by the blood from other parts of the system to the kidneys.

A less common cause is an infection that develops after kidney surgery. Women are at a greater risk for kidney disease than men because the female urethra is shorter than the male urethra; this physiological design makes it easier for the bacteria to get into the urethra and ascend to the kidneys.

People with a weakened immune system due to diseases such as HIV or diabetes are more susceptible to kidney disease. Structural problems such as kidney stones or enlarged prostate glands can produce blockages in the urinary system that restrict or reduce the flow of urine, which increases the risk of infection.

Prolonged use of urinary catheters increases the risk of infection, and if there is a spinal cord injury or nerve damage that blocks the symptoms of bladder infection, the condition can advance to pyelonephritis without the patient being aware of the problem.

A less common cause of pyelonephritis is vesicoureteral reflux (VUR) in which the valve normally preventing a backward flow of urine into the kidneys does not work correctly. Pregnant women have a higher risk of developing kidney disease. 

Diagnosis & Tests

The first step for diagnosis of kidney infection is a urinalysis, which will show if bacteria and white blood cells that indicate infection are present in the urine. A urine culture is then performed in a lab by fostering bacterial growth from the urine sample so the specific bacteria that need to be treated can be identified. Other diagnostic tools include:

Treatment & Therapy

When a person presents with some of the common symptoms of pyelonephritis, the treating physician often chooses to start the patient on a general antibiotic that can fight many common kinds of bacteria. Then, if necessary, the doctor may prescribe a more targeted antibiotic after the lab results identify the specific bacteria causing the infection.

Antibiotics may can be taken orally or by injection and can take several weeks to clear up the problem, and urine cultures will be repeated throughout the treatment until the condition is gone. Even after the infection has been cleared, urine cultures may be taken to make sure the infection has not returned. If the infection is severe, hospitalization may be required.

If the infection is caused by an obstruction blocking the urinary tract or bladder, surgery may be performed to correct the condition. While the symptoms of a kidney infection normally start to clear up in a few days, the full course of antibiotics must be taken to make sure that the infection - not just the symptoms - has been cleared up.

Prevention & Prophylaxis

In order to reduce the potential of developing pyelonephritis, drinking enough water is important, since staying hydrated will cause more frequent urination, which will help the body rid itself of problematic bacteria. Drinking caffeine and alcohol in moderation is advisable, especially for people who suffer from recurring infections.

Urinating soon after having sexual intercourse also helps rid the urethra of harmful bacteria and reduces the chances of developing an infection. For women, who are more prone to develop pyelonephritis, it is important to wipe from front to back after urinating or after a bowel movement; this will help stop the spread of bacteria. People should also be cautious about using products such as douches or deodorant sprays that can irritate the area and make it more vulnerable to infection.