This condition 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.

Kidney infection may be caused by:

• Bladder infection that was not treated or inadequately treated (most common cause)
• 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
• Bacteria from somewhere else in the body that has gone into the kidneys (rare)

These factors increase your chance of developing a kidney infection. Tell your doctor if you have any of these risk factors:

• Sex: female
• Sexual activity
• Pregnancy
• Diabetes
• Birth defect of the urinary tract, including vesicoureteral reflux
• Blockage of the urinary tract, including:
  • Tumors
  • Enlarged prostate gland
  • Kidney stones
• Catheter or stent placed in the urinary tract
• Polycystic kidneys
• Sickle cell anemia
• Previous kidney transplant
• Weakened immune system

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
• Loss of appetite

Your doctor will ask about your symptoms and medical history, and perform a physical exam. A kidney infection is diagnosed with urine tests . The urine is examined for:

• Bacteria
• White blood cells
• Blood
• Other abnormal elements

If the infection does not go away after treatment or if you have had several kidney infections, you may need to have other tests to see if there are problems with the kidney, ureters, and bladder. These tests include:

• Kidney ultrasound —a test that uses sound waves to examine the kidney
• Abdominal CT scan —a type of x-ray that uses a computer to make pictures of structures inside the body
• Voiding cystourethrography— x-ray of the urinary bladder and urethra made after injection with a contrast medium

You will be treated with antibiotics. Be sure to take all of the medication. If the infection is not treated correctly or left untreated, the condition can lead to:

• Sepsis (infection that has spread throughout the body)
• Chronic infection
• Scarring of the kidney
• Permanent kidney damage

In some cases, you may need to stay in the hospital and receive the antibiotics through a vein in your arm.

If you are diagnosed with a kidney infection, follow your doctor's instructions .