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Urinary
Tract Infections Overview
A
urinary tract infection (UTI) is an infection
involving the kidneys, ureters, bladder, or
urethra. These are the structures that urine
passes through before being eliminated from the
body.

- The
kidneys are a pair of small organs that lie on
either side of the spine at about waist level.
They have several important functions in the
body, including removing wastes and excess water
from the blood and eliminating them as
urine.
- The
ureters, 2 narrow tubes about 6 inches long,
drain urine from the kidneys into the
bladder.
- The
bladder is a small saclike organ that collects
and stores urine. When the urine reaches a
certain level in the bladder, the muscle lining
the bladder contracts to expel the
urine.
- The
urethra is a small tube connecting the bladder
with the outside of the body. A muscle called
the urinary sphincter, located at the junction
of the bladder and the urethra, must relax at
the same time the bladder contracts to expel
urine.
Any
part of this system can become infected. As a
rule, the higher up the infection, the more
serious it is.
- The
upper urinary tract is composed of the kidneys
and ureters. Infection in the upper urinary
tract generally affects the kidneys
(pyelonephritis).
- The
lower urinary tract consists of the bladder and
the urethra. Infection in the lower urinary
tract can affect the urethra (urethritis) or the
bladder (cystitis).
Urinary tract infections are usually
referred to as simple or complicated.
- Simple infections occur in healthy
urinary tracts and do not spread to other parts
of the body. They usually go away readily with
treatment.
- Complicated infections are caused by
anatomic abnormalities, spread to other parts of
the body, or are resistant to many antibiotics.
They are more difficult to cure.
In
the United States, urinary tract infections
account for more than 7 million visits to
medical offices and hospitals each
year.
- Urinary tract infection is much more
common in adults than in children, but about
1-2% of children do get urinary tract
infections. Urinary tract infections in children
are more likely to be serious than those in
adults.
- Urinary tract infection is the most
common urinary tract problem in children besides
bed wetting.
- Urinary tract infection is second only to
respiratory infection as the most common type of
infection.
- These infections are much more common in
girls and women than in boys and men younger
than 50 years. The reason for this is not well
understood.
- About 40% of women and 12% of men have a
urinary tract infection at some time in their
life.
- Urinary tract infection is less common in
men and boys than in women and girls but is more
likely to be serious.
Urinary
Tract Infection Causes
The
urine is normally sterile. An infection occurs
when bacteria get into the urine and begin to
grow. The infection usually starts at the
opening of the urethra where the urine leaves
the body and moves upward into the urinary
tract.
- The
culprit in at least 90% of uncomplicated
infections is Escherichia coli, better
know as E coli. These bacteria normally
live in the bowel (colon) and around the
anus.
- These bacteria can move from the area
around the anus to the opening of the urethra.
The two most common causes of this are poor
hygiene and sexual intercourse.
- Usually, the act of emptying the bladder
(urinating) flushes the bacteria out of the
urethra. If there are too many bacteria, this
won't stop them.
- The
bacteria can travel up the urethra to the
bladder, where they can grow and cause an
infection.
- The
infection can spread further as the bacteria
move up from the bladder via the
ureters.
- If
they reach the kidney, they can cause a kidney
infection (pyelonephritis), which can become a
very serious condition if not treated promptly.
The
following people are at increased risk of
urinary tract infection:
- People with conditions that block
(obstruct) the urinary tract, such as kidney
stones.
- People with medical conditions that cause
incomplete bladder emptying (for example, spinal
cord injury or bladder collapse after
menopause.
- People with suppressed immune systems:
Examples of situations in which the immune
system is suppressed are AIDS and diabetes.
People who take immunosuppressant medications
also are at increased risk.
- Women who are sexually active
- Sexual intercourse can introduce larger
numbers of bacteria into the bladder. Infection
is more likely in women who have frequent
intercourse. Infection attributed to frequent
intercourse is nicknamed "honeymoon cystitis."
Urinating after intercourse seems to decrease
the likelihood of developing a urinary tract
infection.
- Women who use a diaphragm for birth
control.
- Men
with an enlarged prostate: Prostatitis or
obstruction of the urethra by an enlarged
prostate can lead to incomplete bladder
emptying, thus increasing the risk of infection.
This is most common in older men.
- Uncircumcised males - This risk is
still relatively low, but it is higher than in
circumcised males.
- Males are also less likely to develop
UTIs because their urethra (tube from the
bladder) is longer. There is a drier
environment where a man’s urethra meets the
outside world, and fluid produced in the
prostate can fight bacteria.
The
following special groups may be at increased
risk of urinary tract infection:
- Very
young infants - Bacteria gain entry to the
urinary tract via the bloodstream from other
sites in the body.
- Young children - Young children have
trouble wiping themselves and washing their
hands well after a bowel movement. Poor hygiene
has been linked to an increased frequency of
urinary tract infections.
- Children of all ages - Urinary tract
infection in children can be (but is not always)
a sign of an abnormality in the urinary tract,
usually a partial blockage. An example is a
condition in which urine moves backward from the
bladder up the ureters (vesicoureteral
reflux).
- Hospitalized patients or nursing home
residents - Many of these individuals are
catheterized for long periods and are thus
vulnerable to infection of the urinary tract.
Catheterization means that a thin tube
(catheter) is placed in the urethra to drain
urine from the bladder. This is done for people
who have problems urinating or cannot reach a
toilet to urinate on their own.
Some
women have frequent urinary tract infections. We
are not really sure why. This may be an
inherited trait, and it may be related to blood
type.
Urinary
Tract Infection Symptoms
Lower
urinary tract infection (cystitis): The lining
of the urethra and bladder becomes inflamed and
irritated.
- Dysuria - Pain or burning during
urination
- Frequency - More frequent urination (or
waking up at night to urinate)
- Urgency - The sensation of not being able
to hold urine
- Hesitancy - The sensation of not being
able to urinate easily or completely (or feeling
that you have to urinate but only a few drops of
urine come out)
- Cloudy, bad smelling, or bloody
urine
- Lower abdominal pain
- Mild
fever (less than 101°F), chills, and "just not
feeling well" (malaise)
Upper
urinary tract infection (pyelonephritis):
Symptoms develop rapidly and may or may not
include the symptoms for a lower urinary tract
infection.
- Fairly high fever (higher than
101°F)
- Shaking chills
- Nausea
- Vomiting
- Flank pain - Pain in your back or side,
usually on only one side at about waist level
In
newborns, infants, children, and elderly people,
the classic symptoms of a urinary tract
infection may not be present. Other symptoms may
indicate a urinary tract infection.
- Newborns - Fever or hypothermia (low
temperature), poor feeding, jaundice
- Infants - Vomiting, diarrhea, fever, poor
feeding, not thriving
- Children - Irritability, eating poorly,
unexplained fever that doesn't go away, loss of
bowel control, loose bowels, change in urination
pattern
- Elderly people - Fever or hypothermia,
poor appetite, lethargy, change in mental status
Typically, pregnant women do not have
unusual or unique symptoms. If you are pregnant,
your urine should be checked during prenatal
visits because an unrecognized infection can
cause pregnancy complications.
Although most people have symptoms with a
urinary tract infection, some do not.
The
symptoms of urinary tract infection can resemble
those of sexually transmitted
diseases.
When to
Seek Medical Care
Any
adult or child who develops any of the symptoms
of a urinary tract infection needs evaluation by
a medical professional, preferably within 24
hours. Most medical offices can test urine for
infection by using a quick urine "dipstick"
test.
- If
you have symptoms of a lower urinary tract
infection, call your health care provider for an
appointment, preferably on the very day that
symptoms are recognized.
- If
you have symptoms of an upper urinary tract
infection involving the kidneys, call your
health care provider immediately. Depending on
the situation, he or she will recommend either a
visit to the office or to a hospital emergency
department.
If
you have symptoms of a lower urinary tract
infection and any of the following applies to
you, you may have a urinary tract infection that
involves the kidneys. Go to a hospital emergency
department right away.
- Vomiting and inability to keep down clear
fluids or medication
- Not
better after taking antibiotics for 2
days
- Pregnant
- Having diabetes or another disease that
affects the immune system (for example,
AIDS)
- Taking medication that suppresses the
immune system
Infants, children, and elderly people
with any of the signs and symptoms should go to
an emergency department for
evaluation.
- Fever, lethargy, and poor appetite may
indicate a simple lower urinary tract infection
in these groups, but they may also be signs of
something more serious.
- Urinary tract infections have the
potential to make these vulnerable people
very ill.
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