The structure of the urinary tract reduces the likelihood of infection by preventing urine from flowing backward toward the kidneys and by washing bacteria out of the body with the normal flow of urine. In men, the prostate gland also produces secretions that slow bacterial growth. Urine is normally sterile.
However, urinary tract infections are common, especially among women. An 287
obstruction of the urinary tract (such as a kidney stone or an enlarged prostate Urinary gland) also increases the risk of infection. People with diabetes, immune disor- Tract ders, or conditions that require regular use of a urinary catheter (a tube inserted through the urethra into the bladder to drain urine from the body) also are at greater risk.
An infection can begin when microorganisms, usually bacteria from the digestive tract (such as Escherichia coli, also called E coli), accumulate at the opening of the urethra. An infection that affects only the urethra is called urethritis. From the urethra, bacteria often move up to the bladder, causing a bladder infection (cystitis). Sexually transmitted microorganisms, such as those that cause gonorrhea and chlamydia, also can infect the urinary tract.
If a bladder infection is not treated promptly, bacteria may move up the ureters, causing a kidney infection (pyelonephritis), which can be serious. Kidney infections also can occur when bacteria or other microorganisms are carried to the kidneys through the bloodstream. When this happens, an obstruction in a ureter can trap infectious agents in the kidneys.
Urinary tract infections do not always cause symptoms. However, most men with a urinary tract infection will experience at least one or two of the following symptoms, especially upon waking in the morning:
A high fever may indicate that the infection has spread to the kidneys. Other symptoms of a kidney infection include pain in the back or side below the ribs, nausea, and vomiting.
A urinary tract infection is diagnosed through a urinalysis and a urine culture. First you provide a "clean catch" urine sample by washing the urethral opening with a disinfecting wipe and collecting a midstream sample (urinate for several seconds before collecting the sample of urine) in a sterile container. The sample is examined under a microscope for blood cells and bacteria. The bacteria will then be grown as a culture to confirm that an infection is present and to identify the bacteria and determine the best antibiotic to kill them. Some bacteria,
Concerns especially those that are sexually transmitted, can be detected only by using special bacterial cultures.
For pyelonephritis, antibiotic treatment may last up to 6 weeks. If the infection does not improve within 3 days of starting treatment, you will need to undergo additional tests to determine whether an obstruction is present or whether an abscess (a cavity filled with pus) has developed. If kidney infections recur frequently, you may develop chronic pyelonephritis, a condition in which a kidney that has been infected several times or damaged by other disease becomes scarred, shrunken, and misshapen.
If the prescribed antibiotics do not eliminate the infection, your doctor probably will perform additional tests, such as intravenous urography or a computed tomography (CT) scan (see "Diagnostic Procedures," page 297) to check for another disorder or an anatomical abnormality.
If you are diagnosed with urethritis caused by a sexually transmitted microorganism, you will need to take measures to protect your sexual partner from infection. Your sexual partner also should be tested and, if necessary, treated for urethritis or any other urinary tract infection that is present. Otherwise you will risk passing the same infection back and forth between you or causing a worse and longer-lasting infection in your partner. You will need to continue using preventive measures such as latex condoms until the infection has been eliminated, not just until the symptoms disappear. Your doctor will tell you when the infection has completely cleared up.
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