Urinary Tract Infections in
Urinary tract infections are
a serious health problem affecting millions of people each year. In 1997, urinary
tract infections (UTIs) accounted for about 8.3 million doctor visits. One
woman in five develops a UTI during her lifetime. UTIs in men are not so
common, but they can be very serious when they do occur.
The key element in the
urinary system is a pair of brown organs located below the ribs called as
the kidneys. The kidneys remove excess liquid and wastes from the blood in
the form of urine, keep a stable balance of salts and other substances in
the blood. Narrow tubes called ureters carry urine from the kidneys to the
bladder, a triangle-shaped chamber in the lower abdomen. Urine is stored in
the bladder and emptied through the urethra.
The average adult passes
about a quart and a half of urine each day. The amount of urine varies,
depending on the fluids and foods a person consumes. The volume formed at
night is about half that formed in the daytime.
Normal urine is sterile. It
contains fluids, salts, and waste products, but it is free of bacteria,
viruses, and fungi. An infection occurs when microorganisms, usually
bacteria from the digestive tract, cling to the opening of the urethra and
begin to multiply. Most infections arise from one type of bacteria,
Escherichia coli (E. coli), which normally lives in the colon. In most
cases, bacteria first begin growing in the urethra. An infection limited to
the urethra is called urethritis. From there bacteria often move on to the
bladder, causing a bladder infection (cystitis). If the infection is not
treated promptly, bacteria may then go up the ureters to infect the kidneys
Chlamydia and Mycoplasma may also cause UTIs, but these infections tend to
remain limited to the urethra. The urinary system is structured in a way
that helps ward off infection. The ureters and bladder normally prevent
urine from backing up toward the kidneys, and the flow of urine from the
bladder helps wash bacteria out of the body. In both sexes, immune defenses
also prevent infection. But despite these safeguards, infections still
Some people are more prone to
getting a UTI than others. Any abnormality of the urinary tract that
obstructs the flow of urine (a kidney stone, for example) sets the stage
for an infection.
A common source of infection
is catheters, or tubes, placed in the bladder. People with diabetes have a
higher risk of a UTI because of changes in the immune system. Any disorder
that suppresses the immune system raises the risk of a UTI.
UTIs may occur in infants who
are born with abnormalities of the urinary tract. In women, though, the
rate of UTIs gradually increases with age. Scientists are not sure why
women have more urinary infections than men. One factor may be that a
woman's urethra is short, allowing bacteria quick access to the bladder.
Many women suffer from
frequent UTIs. Nearly 20 percent of women who have a UTI will have another.
Usually, the latest infection stems from a strain or type of bacteria that
is different from the infection before it, indicating a separate infection.
Research funded by the National Institutes of Health (NIH) is being
Not everyone with a UTI has
symptoms, but most people get at least some. These may include a frequent
urge to urinate and a painful, burning feeling in the area of the bladder
or urethra during urination. It is not unusual to feel bad all over-tired,
shaky, washed out-and to feel pain even when not urinating. It is common
for a person with a urinary infection to complain that, despite the urge to
urinate, only a small amount of urine is passed. The urine itself may look
milky or cloudy, even reddish if blood is present. A fever may mean that
the infection has reached the kidneys. Other symptoms of a kidney infection
include pain in the back or side below the ribs, nausea, or vomiting.
To find out whether you have
a UTI, your doctor will test a sample of urine for pus and bacteria.
Usually, the sample is sent to a laboratory, although some doctors are
equipped to do the testing. In the urine analysis test, the urine is
examined for white and red blood cells and bacteria. The bacteria are grown
and tested against different antibiotics to see which drug best destroys
the bacteria. This last step is called a sensitivity test. When an
infection does not clear up with treatment and is traced to the same strain
of bacteria, the doctor will order a number of tests that makes images of
the urinary tract.
UTIs are treated with
antibacterial drugs. The choice of drug and length of treatment depend on
the patient's history and the urine tests that identify the offending
bacteria. The sensitivity test is especially useful in helping the doctor
select the most effective drug. The drugs most often used to treat routine,
uncomplicated UTIs are trimethoprim, trimethoprim / sulfamethoxazole,
amoxicillin, nitrofurantoin, and ampicillin. A class of drugs called
quinolones includes four drugs approved in recent years for treating UTI.
These drugs include ofloxacin, norfloxacin, ciprofloxacin, and trovafloxin.
Often, a UTI can be cured
with 1 or 2 days of treatment if the infection is not complicated by an
obstruction or nervous system disorder. Still, many doctors ask their
patients to take antibiotics for a week or two to ensure that the infection
has been cured. Single-dose treatment is not recommended for some groups of
patients, for example, those who have delayed treatment or have signs of a
kidney infection, patients with diabetes or structural abnormalities, or
men who have prostate infections. Patients also need longer treatment with
infections caused by Mycoplasma or Chlamydia, which are usually treated
with tetracycline, trimethoprim/sulfamethoxazole, or doxycycline. A
followup urinalysis helps to confirm that the urinary tract is
infection-free. It is important to take the full course of treatment
because symptoms may disappear before the infection is fully cleared.
Severely ill patients with
kidney infections may be hospitalized until they can take fluids and needed
drugs on their own. Kidney infections generally require several weeks of
antibiotic treatment. Researchers at the University of Washington found
that 2-week therapy with TMP/SMZ was as effective as 6 weeks of treatment
with the same drug in women with kidney infections that did not involve an
obstruction or nervous system disorder. In such cases, kidney infections
rarely lead to kidney damage or kidney failure unless they go untreated.
Various drugs are available
to relieve the pain of a UTI. A heating pad may also help. Most doctors
suggest that drinking plenty of water helps cleanse the urinary tract of
bacteria. During treatment, it is best to avoid coffee, alcohol, and spicy
foods. And one of the best things a smoker can do for his or her bladder is
to quit smoking. Smoking is the major known cause of bladder cancer.
In the future, scientists may
develop a vaccine that can prevent UTIs from coming back. Researchers in
different studies have found that children and women who tend to get UTIs
repeatedly are likely to lack proteins called immunoglobulins, which fight
infection. Children and women who do not get UTIs are more likely to have normal
levels of immunoglobulins in their genital and urinary tracts.
Early tests indicate that a
vaccine helps patients build up their own natural infection-fighting
powers. The dead bacteria in the vaccine do not spread like an infection; instead,
they prompt the body to produce antibodies that can later fight against
live organisms. Researchers are testing injected and oral vaccines to see
which works best. Another method being considered for women is to apply the
vaccine directly as a suppository in the vagina.