Pyelonephritis: Kidney Infection National Kidney and Urologic Diseases Information Clearinghouse What is pyelonephritis? Pyelonephritis is a type of urinary tract infection (UTI) that affects one or both kidneys. U.S. Department of Health and Human Services What is the urinary tract? NATIONAL The urinary tract is the body’s drainage INSTITUTES system for removing wastes and extra water. OF HEALTH Kidneys The urinary tract includes two kidneys, two ureters, a bladder, and a urethra. The kidneys are two bean-shaped organs, each about the size of a fist. They are located near the middle of the back, just below the rib cage, one on each side of the spine. Every day, the two kidneys process about Bladder 200 quarts of blood to produce about 1 to Ureters 2 quarts of urine, composed of wastes and extra water. Children produce less urine than adults. The amount produced Urethra depends on their age. The urine flows from the kidneys to the bladder through tubes The urinary tract called the ureters. The bladder stores urine until releasing it through urination. When the bladder empties, urine flows out of the body through a tube called the urethra at the bottom of the bladder. What causes pyelonephritis? What are the symptoms of Pyelonephritis is caused by a bacterium or pyelonephritis? virus infecting the kidneys. Though many Symptoms of pyelonephritis can vary bacteria and viruses can cause pyelonephri­ depending on a person’s age and may tis, the bacterium Escherichia coli is often include the following: the cause. Bacteria and viruses can move to the kidneys from the bladder or can be • fever carried through the bloodstream from other • vomiting parts of the body. A UTI in the bladder that does not move to the kidneys is called • back, side, and groin pain cystitis. • chills • nausea Who is at risk for pyelonephritis? • frequent, painful urination Children younger than 2 years old may only People most at risk for pyelonephritis are have a high fever without symptoms related those who have a bladder infection and to the urinary tract. Older people may not those with a structural, or anatomic, prob­ have any symptoms related to the urinary lem in the urinary tract. Urine normally tract either; instead, they may exhibit confu­ flows only in one direction—from the sion, disordered speech, or hallucinations. kidneys to the bladder. However, the flow of urine may be blocked in people with a structural defect of the urinary tract, a kidney stone, or an enlarged prostate—the walnut-shaped gland in men that surrounds the urethra at the neck of the bladder and supplies fluid that goes into semen. Urine can also back up, or reflux, into one or both kidneys. This problem, which is called vesicoureteral reflux (VUR), happens when the valve mechanism that normally pre­ vents backward flow of urine is not working properly. VUR is most commonly diag­ nosed during childhood. Pregnant women and people with diabetes or a weakened immune system are also at increased risk of pyelonephritis. 2 Pyelonephritis: Kidney Infection What are the complications How is pyelonephritis of pyelonephritis? diagnosed? Most people with pyelonephritis do not The tests used to diagnose pyelonephritis have complications if appropriately treated depend on the patient’s age, gender, and with bacteria-fighting medications called response to treatment and include the antibiotics. following: In rare cases, pyelonephritis may cause • Urinalysis. Urinalysis is testing of a permanent kidney scars, which can lead to urine sample. The urine sample is col­ chronic kidney disease, high blood pres­ lected in a special container in a health sure, and kidney failure. These problems care provider’s office or commercial usually occur in people with a structural facility and can be tested in the same problem in the urinary tract, kidney disease location or sent to a lab for analysis. from other causes, or repeated episodes of The presence of white blood cells and pyelonephritis. bacteria in the urine indicate infection. Infection in the kidneys may spread to the • Urine culture. A urine culture is per­ bloodstream—a serious condition called formed by placing part of a urine sam­ sepsis—though this is also uncommon. ple in a tube or dish with a substance that encourages any bacteria present to grow. The urine sample is collected in a special container in a health care provider’s office or commercial facility and sent to a lab for culture. Once the bacteria have multiplied, which usually takes 1 to 3 days, they can be identi­ fied. The health care provider can then determine the best treatment. 3 Pyelonephritis: Kidney Infection • Ultrasound. Ultrasound uses a device, • Voiding cystourethrogram (VCUG). A called a transducer, that bounces safe, VCUG is an x-ray image of the bladder painless sound waves off organs to and urethra taken while the bladder is create an image of their structure. The full and during urination, also called procedure is performed in a health voiding. The procedure is performed care provider’s office, outpatient cen­ in an outpatient center or hospital by ter, or hospital by a specially trained an x-ray technician supervised by a technician, and the images are inter­ radiologist, who then interprets the preted by a radiologist—a doctor who images. Anesthesia is not needed, but specializes in medical imaging; anes­ sedation may be used for some people. thesia is not needed. The images can The bladder and urethra are filled show obstructions in the urinary tract. with contrast medium to make the Ultrasound is often used for people structures clearly visible on the x-ray who do not respond to treatment images. The x-ray machine captures within 72 hours. images of the contrast medium while • Computerized tomography (CT) scan. the bladder is full and when the person CT scans use a combination of x rays urinates. This test can show abnormal­ and computer technology to create ities of the inside of the urethra and three-dimensional (3-D) images. A bladder and is usually used to detect CT scan may include the injection of VUR in children. a special dye, called contrast medium. • Digital rectal examination (DRE). A CT scans require the person to lie DRE is a physical exam of the pros­ on a table that slides into a tunnel- tate that is performed in the health shaped device where the x rays are care provider’s office. Anesthesia is taken. The procedure is performed in not needed. To perform the exam, the an outpatient center or hospital by an health care provider asks the person x-ray technician, and the images are to bend over a table or lie on his side interpreted by a radiologist. Anes­ while holding his knees close to his thesia is not needed. CT scans can chest. The health care provider slides show obstructions in the urinary tract. a gloved, lubricated finger into the The test is often used for people who rectum and feels the part of the pros­ do not respond to treatment within tate that lies in front of the rectum. 72 hours. Men with suspected pyelonephritis may have a DRE to determine whether a swollen prostate may be obstructing the neck of the bladder. 4 Pyelonephritis: Kidney Infection • Dimercaptosuccinic acid (DMSA) How is pyelonephritis scintigraphy. DMSA scintigraphy is an imaging technique that relies on treated? the detection of small amounts of Pyelonephritis is treated with antibiotics, radiation after injection of radioac­ which may need to be taken for several tive material. Because the dose of weeks. While a urine sample is sent to a radioactive material is small, the risk lab for culture, the health care provider of causing damage to cells is low. The may begin treatment with an antibiotic that procedure is performed in an outpa­ fights the most common types of bacteria. tient center or hospital by a specially Once culture results are known and the trained technician, and the images are bacteria is clearly identified, the health care interpreted by a radiologist. Anesthe­ provider may switch the antibiotic to one sia is not needed. Radioactive material that more effectively targets the bacteria. is injected into a vein in the person’s Antibiotics may be given through a vein, arm and travels through the body to orally, or both. Urinary tract obstructions the kidneys. Special cameras and are often treated with surgery. computers are used to create images Severely ill patients may be hospitalized of the radioactive material as it passes and limited to bed rest until they can take through the kidneys. The radioactive the fluids and medications they need on material makes the parts of the kidney their own. Fluids and medications may be that are infected or scarred stand out given intravenously during this time. on the image. DMSA scintigraphy is used to show the severity of kidney In adults, repeat urine cultures should be infection or kidney damage, such as performed after treatment has ended to scarring. make sure the infection does not recur. If a repeat test shows infection, another 14-day course of antibiotics is prescribed; if infec­ tion recurs again, antibiotics are prescribed for 6 weeks. Eating, Diet, and Nutrition Eating, diet, and nutrition have not been shown to play a role in causing or prevent­ ing pyelonephritis. 5 Pyelonephritis: Kidney Infection Hope through Research Points to Remember The National Institute of Diabetes and • Pyelonephritis is a type of urinary Digestive and Kidney Diseases (NIDDK) tract infection that affects one or sponsors several programs aimed at under­ both kidneys. standing urologic diseases in adults and children. The NIDDK’s Division of Kid­ • Pyelonephritis is caused by a bacte­ ney, Urologic, and Hematologic Diseases rium or virus infecting the kidneys.