What is pyelonephritis?

Pyelonephritis is a bacterial infection of the kidney. It is potentially serious because of the important function of the kidneys and because the infection may also be in the bloodstream.

Kidney infections are much more common in women than men.

How does it occur?

Most kidney infections result from lower urinary tract infections, usually of the bladder. (An infection of the bladder is called cystitis.) When a person has a bladder infection, the usual mechanism that prevents urine from flowing back to the kidneys does not work properly. This malfunction can allow infected urine to move into the kidneys.

The urinary system is a common site of congenital abnormalities (birth defects). If your urinary system is abnormal, it is more likely that a lower urinary tract infection will spread to the kidneys.

The urethra is the tube that empties urine from the bladder. In men the urethra extends the full length of the penis. A woman's urethra is much shorter, about an inch long, and is positioned immediately above the vagina. Because the urethra is so close to the vagina and anus, bacteria can easily enter it from these areas. As a result, women are more prone to have bladder infections than men. However, men do sometimes develop lower urinary tract infections. Often these infections in men result from prostate infections. These lower urinary tract infections may then spread to the kidneys, causing pyelonephritis.

Men or women who have blockage from a kidney stone are at risk for developing pyelonephritis.

What are the symptoms?

The symptoms of pyelonephritis range from mild to severe and may include any of the following:

• fever

• chills

• sweats

• abdominal pain

• back pain

• loss of appetite

• nausea

• vomiting

• problems with urination, such as pain when you urinate.

Sometimes it is difficult to know whether urinary symptoms are caused by an infection of the lower urinary tract (for example, bladder or prostate) or by a kidney infection. In either case, these symptoms should not be ignored. If you have urinary tract symptoms, see your health care provider immediately. Even a simple bladder infection can rapidly progress to pyelonephritis and infection in the bloodstream. Do not allow the symptoms to continue for several days before you seek evaluation and treatment.

How is it diagnosed?

Your health care provider reviews your medical history, looking especially for current or recent lower urinary tract infection. You will also be examined, especially to check for pain in the kidney area. A sample of your urine is examined in the lab (urinalysis). A sample of urine is also incubated in the lab (urine culture). The organisms that grow from the urine sample are identified and tested to see which antibiotics will kill them.

How is it treated?

Antibiotics are the primary treatment for a kidney infection. Your doctor may treat you first as an outpatient. You may continue to be treated at home if you show a good response to the antibiotic after 24 hours. If you are more seriously ill or dehydrated or not responding to outpatient antibiotics, you may need to stay in the hospital. You can be given IV medication and fluid therapy in the hospital.

You will need to take antibiotics for at least 10 days. All bacteria must be killed to prevent kidney damage and recurrence of the infection.

Your antibiotic may need to be changed after the first day or two of treatment if urine culture results show a different antibiotic will work better. Your health care provider will call you if this is the case.

How long do the symptoms last?

How long it takes you to recover depends on the severity of your symptoms when you start treatment. In mild cases, symptoms lessen in the first 1 to 2 days. More severe cases require several days before you begin to feel better.

With proper treatment there are few complications of pyelonephritis. If your symptoms return soon after you finish your treatment, further tests may be necessary. Your doctor will determine whether an underlying cause is present, such as a kidney stone or kidney abscess.

How can I take care of myself?

• Notice whether your symptoms are responding to the antibiotic treatment.

• Drink a lot of fluids.

• Promptly report to your doctor worsening or recurrent symptoms.

What can be done to help prevent pyelonephritis?

Most cases of pyelonephritis in women result from bladder infections. The best way to prevent kidney infections is to try to prevent bladder infections. Ways to try to prevent these infections include:

• Drink plenty of water and other noncaffeinated drinks. (Caffeine can cause a loss of fluids.)

• Avoid contaminating the urethra with bacteria from the anal area by practicing good hygiene when you use the bathroom.

• Avoid using irritating cosmetics or chemicals in the area of the vagina and urethra.

• Urinate after each time you have sexual intercourse.

There are no specific preventive measures for men other than drinking plenty of fluids and practicing good genital hygiene, especially for uncircumcised men.