tract infections are a serious health problem affecting millions of people each
Infections of the urinary tract are common—only respiratory infections occur
more often. In 1997, urinary tract infections (UTIs) accounted for about 8.3
million doctor visits.* Women are especially prone to UTIs for reasons that are
poorly understood. 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.
*Ambulatory Care Visits to Physician Offices, Hospital
Outpatient Departments, and Emergency Departments: United States, 1997. Vital
and Health Statistics. Series 13, No. 143. Atlanta, GA: National Center for
Health Statistics, Centers for Disease Control and Prevention, U.S. Dept. of
Health and Human Services; November 1999.
system consists of the kidneys, ureters, bladder, and urethra. The key elements
in the system are the kidneys, a pair of purplish-brown organs located below the
ribs toward the middle of the back. 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, and produce a hormone that aids the formation of red
blood cells. 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.
What are the causes of UTI?
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
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
Microorganisms called Chlamydia and Mycoplasma may also cause UTIs
in both men and women, but these infections tend to remain limited to the
urethra and reproductive system. Unlike E. coli, Chlamydia and
Mycoplasma may be sexually transmitted, and infections require treatment of
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
men, the prostate gland produces secretions that slow bacterial growth. In both
sexes, immune defenses also prevent infection. But despite these safeguards,
infections still occur.
Who is at risk?
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. An enlarged prostate gland
also can slow the flow of urine, thus raising the risk of infection.
A common source of infection is catheters, or tubes, placed in the bladder. A
person who cannot void or who is unconscious or critically ill often needs a
catheter that stays in place for a long time. Some people, especially the
elderly or those with nervous system disorders who lose bladder control, may
need a catheter for life. Bacteria on the catheter can infect the bladder, so
hospital staff take special care to keep the catheter sterile and remove it as
soon as possible.
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 urinary infection.
UTIs may occur in infants who are born with abnormalities of the urinary tract,
which sometimes need to be corrected with surgery. UTIs are rarely seen in boys
and young men. 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. Also, a woman's urethral opening is near sources of bacteria from
the anus and vagina. For many women, sexual intercourse seems to trigger an
infection, although the reasons for this linkage are unclear.
According to several studies, women who use a diaphragm are more likely to
develop a UTI than women who use other forms of birth control. Recently,
researchers found that women whose partners use a condom with spermicidal foam
also tend to have growth of E. coli bacteria in the vagina.
Many women suffer from frequent UTIs. Nearly 20 percent of
women who have a UTI will have another, and 30 percent of those will have yet
another. Of the last group, 80 percent will have recurrences.
Usually, the latest infection stems from a strain or type of bacteria that is
different from the infection before it, indicating a separate infection. (Even
when several UTIs in a row are due to E. coli, slight differences in the
bacteria indicate distinct infections.)
Research funded by the National Institutes of Health (NIH) suggests that one
factor behind recurrent UTIs may be the ability of bacteria to attach to cells
lining the urinary tract. A recent NIH-funded study found that bacteria formed a
protective film on the inner lining of the bladder in mice. If a similar process
can be demonstrated in humans, the discovery may lead to new treatments to
prevent recurrent UTIs. Another line of research has indicated that women who
are "non-secretors" of certain blood group antigens may be more prone to
recurrent UTIs because the cells lining the vagina and urethra may allow
bacteria to attach more easily. Further research will show whether this
association is sound and proves useful in identifying women at high risk for
Infections in Pregnancy
Pregnant women seem no more prone to UTIs than other women.
However, when a UTI does occur, it is more likely to travel to the kidneys.
According to some reports, about 2 to 4 percent of pregnant women develop a
urinary infection. Scientists think that hormonal changes and shifts in the
position of the urinary tract during pregnancy make it easier for bacteria to
travel up the ureters to the kidneys. For this reason, many doctors recommend
periodic testing of urine.
What are the symptoms of UTI?
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. Often women feel an uncomfortable pressure above the pubic bone,
and some men experience a fullness in the rectum. 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.
In children, symptoms of a urinary infection may be overlooked or attributed to
another disorder. A UTI should be considered when a child or infant seems
irritable, is not eating normally, has an unexplained fever that does not go
away, has incontinence or loose bowels, or is not thriving. The child should be
seen by a doctor if there are any questions about these symptoms, especially a
change in the child's urinary pattern.
How is UTI diagnosed?
To find out whether you have a UTI, your doctor will test a
sample of urine for pus and bacteria. You will be asked to give a "clean catch"
urine sample by washing the genital area and collecting a "midstream" sample of
urine in a sterile container. (This method of collecting urine helps prevent
bacteria around the genital area from getting into the sample and confusing the
test results.) Usually, the sample is sent to a laboratory, although some
doctors' offices are equipped to do the testing.
In the urinalysis test, the urine is examined for white and red blood cells and
bacteria. Then the bacteria are grown in a culture and tested against different
antibiotics to see which drug best destroys the bacteria. This last step is
called a sensitivity test.
Some microbes, like Chlamydia and Mycoplasma, can be detected only
with special bacterial cultures. A doctor suspects one of these infections when
a person has symptoms of a UTI and pus in the urine, but a standard culture
fails to grow any bacteria.
When an infection does not clear up with treatment and is traced to the same
strain of bacteria, the doctor will order a test that makes images of the
urinary tract. One of these tests is an intravenous pyelogram (IVP), which gives
x-ray images of the bladder, kidneys, and ureters. An opaque dye visible on
x-ray film is injected into a vein, and a series of x rays is taken. The film
shows an outline of the urinary tract, revealing even small changes in the
structure of the tract.
If you have recurrent infections, your doctor also may recommend an ultrasound
exam, which gives pictures from the echo patterns of soundwaves bounced back
from internal organs. Another useful test is cystoscopy. A cystoscope is an
instrument made of a hollow tube with several lenses and a light source, which
allows the doctor to see inside the bladder from the urethra.
How is UTI treated?
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 (Trimpex),
trimethoprim/sulfamethoxazole (Bactrim, Septra, Cotrim), amoxicillin (Amoxil,
Trimox, Wymox), nitrofurantoin (Macrodantin, Furadantin), and ampicillin. A
class of drugs called quinolones includes four drugs approved in recent years
for treating UTI. These drugs include ofloxacin (Floxin), norfloxacin (Noroxin),
ciprofloxacin (Cipro), and trovafloxin (Trovan).
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. Longer treatment is also needed by patients
with infections caused by Mycoplasma or Chlamydia, which are
usually treated with tetracycline, trimethoprim/sulfamethoxazole (TMP/SMZ), 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
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
Doctors suggest some additional steps that a woman can take on her own to avoid
- Drink plenty of water every day.
- Urinate when you feel the need; don't resist the urge to
- Wipe from front to back to prevent bacteria around the anus
from entering the vagina or urethra.
- Take showers instead of tub baths.
- Cleanse the genital area before sexual intercourse.
- Avoid using feminine hygiene sprays and scented douches,
which may irritate the urethra.
- Some doctors suggest drinking cranberry juice.
Infections in Pregnancy
A pregnant woman who develops a UTI should be treated promptly
to avoid premature delivery of her baby and other risks such as high blood
pressure. Some antibiotics are not safe to take during pregnancy. In selecting
the best treatments, doctors consider various factors such as the drug's
effectiveness, the stage of pregnancy, the mother's health, and potential
effects on the fetus.
Curing infections that stem from a urinary obstruction or
nervous system disorder depends on finding and correcting the underlying
problem, sometimes with surgery. If the root cause goes untreated, this group of
patients is at risk of kidney damage. Also, such infections tend to arise from a
wider range of bacteria, and sometimes from more than one type of bacteria at a
Infections in Men
UTIs in men usually stem from an obstruction—for example, a
urinary stone or enlarged prostate—or from a medical procedure involving a
catheter. The first step is to identify the infecting organism and the drugs to
which it is sensitive. Usually, doctors recommend lengthier therapy in men than
in women, in part to prevent infections of the prostate gland.
Prostate infections (chronic bacterial prostatitis) are harder to cure because
antibiotics are unable to penetrate infected prostate tissue effectively. For
this reason, men with prostatitis often need long-term treatment with a
carefully selected antibiotic. UTIs in older men are frequently associated with
acute bacterial prostatitis, which can be fatal if not treated immediately.
Is there a vaccine to prevent recurrent UTIs?
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.
Kidney and Urologic Diseases Information Clearinghouse
3 Information Way
Bethesda, MD 20892–3580
Nutritional and Herbal Therapy for Urinary
- Drink plenty of water and caffeine-free herbal teas. Avoid
- Drink unsweetened cranberry juice. Cranberries
acidify the urine which inhibits bacteria from adhering to the urinary tract.
- Vitamin C (250 to 500 mg twice a day) also acidifies
urine and it boosts immunity.
- Zinc (30 to 50 mg a day) increases immunity.
- Acidophilus is important to take if you are taking
antibiotics. Not only does antibiotics kill bad bacteria but it also kills the
good and vital bacterial flora in your digestive tract. Taking acidophilus
helps replenish your body's flora. Plain yogurt is a good source.
Tao of Nutrition recommends drinking plenty of cornsilk tea (which is
readily available at your local health food store).
Tao of Nutrition, by Maoshing Ni, Ph.D., C.A., and Cathy McNease,