Kidney Infection (Pyelonephritis)

Pyelonephritis is an infection of one or both kidneys. It often starts as a urinary tract infection, or U-T-I. A U-T-I is a common infection that occurs when bacteria, or sometimes viruses, enter the urinary tract. They usually enter through the urethra. This is the tube that carries urine out of your body.

If the urethra is infected, the U-T-I is called urethritis. Bacteria or viruses may move from your urethra to your bladder. This is where urine is stored before leaving your body. If a U-T-I stays in the bladder, it is called cystitis.

But sometimes bacteria or viruses move from the bladder to the kidneys, where urine is made. Bacteria or viruses can also go to the kidneys from other parts of the body through the bloodstream. This kind of infection is called pyelonephritis. Bacteria called E. coli are the most common cause of pyelonephritis. It is a less common type of UTI. It is also more serious and needs medical attention right away.


Symptoms of pyelonephritis can vary depending on your age. They can include fever, vomiting, and pain in your back, side, or groin. You may have chills and frequent, painful urination. Young children may only have a high fever. Older people may show confusion or have hallucinations.


To find out if you have pyelonephritis, your healthcare provider will ask you about your medical history and give you a physical exam. Other tests may be given depending on your age, gender, and response to treatment. Your urine may be tested for white blood cells and bacteria. A urine culture may be done to show which bacteria are in the urine. This helps to guide the type of treatment.

Imaging studies may be done. These may include an ultrasound, which uses sound waves and a computer to make images. You may have a computed tomography scan, also called C-T scan. This creates an image using X-rays put together by a computer. These studies can show if there are blockages in the urinary tract. Other tests may also be done.


Pyelonephritis is treated with antibiotics. You may need to take them for several weeks, starting with one type that fights the most common types of bacteria If tests show a different bacteria is causing the infection, you may be switched to a different antibiotic.

Antibiotics may be taken by mouth, given through a vein, or both. You may need to be in the hospital if you have a severe infection or other health problems. A blockage in the urinary tract is often treated with surgery.

Your urine will be tested after treatment has ended. This is to make sure the infection has not come back. If the test shows the infection has not gone away or has come back, you will need to have more antibiotics.  Most people with pyelonephritis do not have complications if they have the right antibiotics.

Repeat infections can hurt the kidneys and lead to scarring. Very rarely, a person can have a blockage or other problem in the urinary tract that causes an infection that does not go away. This is called chronic pyelonephritis. It can cause kidney failure. If your kidneys stop working, you may need dialysis or a kidney transplant.

Pyelonephritis in pregnancy may lead to preterm labor, severe infection, and other problems.


You can help keep your urinary tract healthy. Drink plenty of water throughout the day. Drink cranberry juice, too. It has been shown to help stop bacteria from sticking to the walls of the urethra. Vitamin C supplements may also help. Don’t use bubble bath or bath oils that may irritate the urethra. Don’t resist the urge to urinate -- go when you need to. Whenever you urinate, wash the area afterwards using plain, unscented soap. This helps keep bacteria from entering the urethra or vagina.

What We Have Learned

  1. Symptoms of pyelonephritis can vary by age. True or false?
    The answer is True. For example, young children may only have a fever.

  2. A urine culture is only done in some cases. True or false?
    The answer is False. A urine culture is done to show which bacteria are causing the infection. This helps guide the type of treatment.

  3. Imaging studies can help to show if there is a blockage. True or false?
    The answer is True. Imaging studies such as a C-T can show a blockage in the urinary tract.