Urinary tract infections are a serious health problem affecting millions of people each
year.
Infections of the urinary tract are common--only respiratory infections occur more
often. Each year, urinary tract infections (UTIs) account for about 9.6 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.
The urinary 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 liquid waste 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.
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
live 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 (pyelonephritis).
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 both partners.
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. Despite these safeguards, though, infections still occur.
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.
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.
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 if there is a change in he child's urinary pattern.
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).
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. For the time being, 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.)
A woman who has frequent recurrences (three or more a year) should ask her doctor about
one of the following treatment options:
- Take low doses of an antibiotic such as TMP/SMZ or nitrofurantoin daily for 6 months
or longer. - Take a single dose of an antibiotic after sexual intercourse.
- Take a short course (1 or 2 days) of antibiotics when symptoms appear.
Dipsticks that change color when an infection is present are now available without
prescription. The strips detect nitrite, which is formed when bacteria change nitrate in
the urine to nitrite.
Doctors suggest some additional steps that a woman can take on her own to avoid an infection:
- Drink plenty of water every day. Some doctors suggest drinking cranberry juice,
which in large amounts inhibits the growth of some bacteria by acidifying the urine.
Vitamin C (ascorbic acid) supplements have the same effect. - Urinate when you feel the need; don't resist the urge to urinate.
- 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.
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.
Complicated Infections
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 time.
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.
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 injection 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.
