Written by Christine DiMaria and Matthew Solan | Published on July 25, 2012
Medically Reviewed by Sylvia S. Hanna, MD on July 25, 2012

What Is Pyelonephritis?

Acute pyelonephritis is a sudden and severe kidney infection. This condition causes the kidneys to swell, can permanently damage the kidneys, and can even be life threatening. It is important to recognize the symptoms so you can seek immediate medical attention. When there are repeated or persistent attacks, the condition is called chronic pyelonephritis. The chronic form of the condition is rare.

What Are The Symptoms of Pyelonephritis?

Symptoms usually appear within one to two days after the infection begins. They may be different in children and the elderly than they are in adolescents and non-elderly adults. However, common symptoms include the following:

  • a fever of more than 102 degrees
  • abdominal, back, side, or groin pain
  • painful or burning urination
  • cloudy urine
  • pus or blood in urine
  • urgent and/or frequent urination
  • fishy-smelling urine

Other symptoms can include:

  • shaking/chills
  • nausea
  • vomiting
  • general aching or ill feeling
  • fatigue
  • moist skin
  • mental confusion (common in the elderly and often their only symptom)

Patients with chronic pyelonephritis may experience only mild or even a lack of noticeable symptoms

What Causes Pyelonephritis?

The infection usually starts in the lower urinary tract as a urinary tract infection. Bacteria enter your body through the tube that carries urine from your body (urethra) and begin to multiply and spread up to the bladder. From the bladder, the bacteria travel up through the ureters to the kidneys. Bacteria, such as Escherichia coli, commonly known as E. coli, often cause the infection. But any serious infection in the blood stream can spread to the kidneys and cause acute pyelonephritis.

Chronic pyelonephritis is more common in children or in patients with urinary obstructions.

Who Is at Risk for Pyelonephritis?

When the urinary tract is of unusual size or shape, it is more likely that infections can lead to acute pyelonephritis. Anyone with chronic kidney stones or other kidney or bladder conditions are also at risk. Whenever there is a problem that interrupts the normal flow of urine there is a greater risk of acute pyelonephritis.

A woman’s urethra is much shorter than a man’s, which makes it easy for bacteria to enter the body. This makes women more prone to kidney infections than men and at higher risk for acute pyelonephritis. The elderly also have an increased risk of kidney infections. People with suppressed immune systems, such as those with diabetes, AIDS or cancer, are also at higher risk.

There are also other factors that can make you vulnerable to infection, such as:

  • using a catheter
  • undergoing a cystoscopic examination
  • having urinary tract surgery
  • having an enlarged prostate
  • certain medications
  • nerve or spinal cord damage

People with vesicoureteral reflux—when small amounts of urine back up from the bladder into the ureters and kidneys—are also at high risk for this disease.

Chronic forms of the condition are more common in people with urinary obstructions. These can be caused by urinary tract infections, vesicoureteral reflux, or anatomical anomalies. Chronic pyelonephritis is more common in children than in adults.

How Is Pyelonephritis Diagnosed?

A doctor will check for tenderness in the abdomen, fever, and other common symptoms. If a kidney infection is suspected, the doctor will order a urine test to check for bacteria. The urine will also be checked for concentration, blood, and pus. The doctor may also order X-rays or an ultrasound to look for cysts or tumors in the urinary tract.

Treatment Options for Pyelonephritis

Antibiotics are the first course of action against acute pyelonephritis. But the type of antibiotic depends upon whether or not the bacteria can be identified. If the type cannot be identified, a broad-spectrum antibiotic will be used. Although treatment can cure the infection within two to three days, the medication must be taken for the entire prescription period, usually 10 to 14 days. Antibiotics options are:

  • levofloxacin
  • ciprofloxacin
  • co-trimoxazole
  • ampicillin

In some cases, drug therapy is ineffective. For a severe kidney infection, your doctor may admit you to the hospital. Treatment in the hospital may include antibiotics that you receive through a vein in your arm (intravenously). How long you’ll stay in the hospital depends on the severity of your condition.

Recurrent kidney infections may result from an underlying medical problem. Surgery may be needed to remove any obstructions or correct any structural problems in the kidney that are causing the problem.

What Are Potential Complications of Pyelonephritis?

Chronic kidney disease is a possible complication of acute pyelonephritis. And if the infection continues to recur, the kidneys may be permanently damaged. Although rare, it is possible for the infection to enter the blood stream, resulting in a potentially deadly bloodstream infection called sepsis.

Other complications include:

  • recurring kidney infections
  • the infection spreading to areas around the kidneys
  • acute kidney failure
  • kidney abscess
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