What is kidney infection?

Definition

Kidney infection occurs when there is a bacterial
infection in one or both kidneys. The kidneys remove waste
(in the form of urine) from the body. They also balance the water and electrolyte
content in the blood by filtering salt and water.

Causes

Kidney infection may be caused by, most commonly, a bladder infection that was not treated or inadequately treated;
conditions that slow the flow of urine from the bladder, such as an enlarged
prostate or kidney stones; having a cystoscopy
done to examine the bladder; surgery of the urinary tract; use of a catheter to drain urine from the bladder; and, rarely, bacteria from
another part of the body that has entered the kidneys.

Risk Factors

The factors that increase the chance of developing kidney infection include
sexual activity; pregnancy; diabetes; birth disorder of the urinary tract,
including vesicoureteral reflux; blockage of the urinary tract, including tumors,
an enlarged prostate gland, kidney stones, or a catheter or stent placed in the
urinary tract; polycystic kidneys; sickle cell anemia; previous kidney
transplant; and a weakened immune system. Also, girls and women are at greater
risk for kidney infection.

Symptoms

Symptoms include pain in the abdomen, lower back,side, or groin; frequent urination; urgent urination that produces only a small amount of urine; sensation of a full bladder, even after urination; burning pain with urination; fever and chills; nausea and vomiting; pus and blood in the urine; and loss of appetite.

Screening and Diagnosis

A doctor will ask about symptoms and medical history and will perform a physical exam. Kidney infection is diagnosed with urine tests. The urine is examined for bacteria, white blood cells, blood, and other abnormal elements.

If the infection does not go away after treatment or if the person has had
several kidney infections, other tests might be ordered to see if there are
problems with the kidney, ureters, and bladder. These tests include a kidney
ultrasound (a test that uses sound waves to examine the kidney); an abdominal
computed
tomography (CT) scan (a detailed X-ray picture that
identifies abnormalities of fine tissue structure); and a voiding
cystourethrography (an X ray of the urinary bladder and urethra made after
injection with a contrast medium).

Treatment and Therapy

Kidney infections are treated with antibiotics. If the infection is not
treated correctly or is left untreated, the condition can lead to septicemia (a
blood infection that has spread throughout the body), chronic infection, scarring
of the kidney, or permanent kidney damage. In some cases, the infected person may
need to be hospitalized and may need to receive antibiotics intravenously.

Prevention and Outcomes

Because kidney infection is often a complication of a bladder infection, the chance of getting a bladder infection can be lessened by drinking increased amounts of fluids (about eight to ten 8-ounce glasses per day); this includes drinking cranberry juice, which may help prevent bladder infection too. Other preventive measures are to practice good hygiene, to urinate when the need arises, and to take showers rather than baths. Women should wipe from the front to the back after using the toilet, should urinate before and after having sex, and should avoid douches and genital deodorant sprays.

Bibliography

Brenner, Barry M., ed. Brenner and Rector’s The Kidney. 8th ed. Philadelphia: Saunders/Elsevier, 2008.

Greenberg, Arthur, et al., eds. Primer on Kidney Diseases. 4th ed. Philadelphia: Saunders/Elsevier, 2005.

Kiel, Raphael, et al. “Does Cranberry Juice Prevent or Treat Urinary Tract Infection?” Journal of Family Practice 52, no. 2 (February, 2003): 154-155.

O’Callaghan, C. A., and Barry M. Brenner. The Kidney at a Glance. Malden, Mass.: Blackwell Science, 2000.

Parker, James N., and Philip M. Parker, eds. The 2002 Official Patient’s Sourcebook on Pyelonephritis. San Diego, Calif.: Icon Health, 2002.

Walsh, Patrick C., et al., eds. Campbell-Walsh Urology. 4 vols. 9th ed. Philadelphia: Saunders/Elsevier, 2007.