A urinary tract infection occurs when bacteria enter the urinary tract. The most common type is a bladder infection. UTIs are usually caused by E. coli bacteria entering through the urethra. Symptoms depend on the location but can include pain during urination and cloudy urine. Treatment typically involves antibiotics, while prevention focuses on hygiene and drinking cranberry juice or capsules. Complications can include kidney damage if left untreated.

1. What Is Urinary Tract Infection? What Causes Urinary Tract Infection?
Last updated on Tuesday 3 December 2013
Originally published on Wednesday 26 May 2010
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A urinary tract infection, also known as UTI, is usually a bacterial infection1 that affects the
urinary system. The urinary system produces, stores and eliminates urine and consists of two
kidneys, two ureters, the bladder, the urethra and two sphincter muscles.
A urinary tract infection can affect any part of the urinary tract. The urinary tract is also known as
the urinary system.
UTI is nearly always caused by bacteria, specifically Escherichia coli (E. coli). Urine contains a
range of salts, fluids and waste products, but is usually bacterium-free. When bacteria enter the
urinary tract, e.g. the bladder or kidney, they can reproduce rapidly in the urine, causing urinary
tract infection.
In this Medical News Today information page, you can read about:
What is UTI?
Signs and symptoms.
Risk factors.
Causes.
Diagnosis.
Treatment options.
Complications.
Prevention.
What is urinary tract infection?
The urinary system produces, stores and eliminates urine, one of the body's liquid waste
products. The urinary tract includes:
Kidneys - they remove waste and water from the blood and produce urine.
Ureters - small tubes that transport urine from the kidneys to the bladder.
Bladder - a sac that stores urine.
Urethra - a tube by which urine is conveyed out of the body from the bladder. In males, semen
passes through the urethra.
Sphincter muscles - the flow of urine through the urethra is controlled by the internal and external
urethral sphincter muscles.
Anatomy and physiology of animals Urinary system
UTI can occur in any part of the urinary system.
There are usually no germs (bacteria) in normal urine. However, sometimes bacteria from outside
or inside the body can get into the urinary system and cause inflammation and infection. Any part
of the urinary tract may be infected:

2. Urethritis is infection of the urethra.
Ureteritis is infection of a ureter.
Pyelonephritis is infection of the kidneys.
Cystitis is infection of the bladder.
Cystitis, often referred to as a bladder infection, is the most common type of UTI. A kidney
infection is potentially more serious3. Infections of the bladder and/or urethra are known as lower
urinary tract infections; if it occurs in the kidneys or ureters they are known as upper urinary tract
infections.
Urinary tract infections are generally easily and effectively treated with a short course of
antibiotics. However, infection can cause discomfort, with the patient experiencing pain during
urination, a frequent urge to urinate, and cloudy urine.
Females are more susceptible to UTIs than males. According to the National Health Service
(NHS), UK, 1 in every 3 women will have a UTI before she is 24 years old, and about half of all
females will have at least one UTI during their lifetime. Approximately 1 in every 2,000 otherwise
healthy men develops UTI every year2.
What are the signs and symptoms of urinary tract infection?
A symptom is something the patient senses and describes, while a sign is something other
people, such as the doctor notice. For example, drowsiness may be a symptom while dilated
pupils may be a sign.
Signs and symptoms of a urinary tract infection depend on whether the lower or upper urinary
tract is affected.
Lower urinary tract infection (affects bladder and/or urethra):
Cloudy urine
The urine may have an unpleasant smell
Hematuria - blood in urine
Frequent need to urinate - this may occur during the waking hours, sleeping hours, or both
Holding the urine in may become harder to do
Discomfort and sometimes pain when urinating
Abdominal pain
Back pain
General malaise; generally feeling unwell
Tenderness around the pelvic area
Upper urinary tract infection (affects kidneys and/or ureters):
Fever, usually high (at least 38C or 100.4F)
Shivering
Vomiting
Nausea
Diarrhea
Pain on the side (flank), upper back or groin - this may become more uncomfortable when
urinating
Lower UTI symptoms - if the infection spreads to the lower urinary tract, the patient may also
have those symptoms.
Older patients are more likely to have urinary tract infection with no symptoms4.
What are the risk factors for urinary tract infection?
A risk factor is something which increases the likelihood of developing a condition or disease. For
example, obesity significantly raises the risk of developing diabetes type 2. Therefore, obesity is a

3. risk factor for diabetes type 2.
Gender - females are significantly more likely to develop a UTI than males, although the
prevalence in elderly men and women is similar5. Females have a shorter urethra, making the
distance to the bladder shorter and the likelihood of the infection moving upwards to the bladder
greater. A woman's urethra opening is much nearer the anus than a man's. Consequently, there is
a higher risk of bacteria entering the urethra from the anus.
Sexual activity - UTIs are more common among females who are sexually active.
Some forms of birth control - females who use diaphragms for birth control tend to be more
susceptible to UTIs.
Age - women are more susceptible to UTIs after the menopause. During the menopause women
produce less mucus in the vaginal area. This mucus stops the bacteria from multiplying. Women
on HRT (hormone replacement therapy) have a lower risk of developing cystitis compared to
menopausal women not on HRT. During the menopause the lining of a woman's urethra gets
thinner as her levels of estrogen drop. The thinner the lining becomes, the higher the chances are
of infection and damage.
Kidney problems - people with kidney stones and some other kidney problems are more likely to
develop infections.
Some chronic illnesses - especially those that weaken the immune system may increase the risk
of developing UTIs, such as diabetes.
Long-term catheter use - patients with a urinary catheter have a higher risk of UTI (if used for a
long time).
What are the causes of urinary tract infection?
Most commonly, a urinary tract infection occurs when gastrointestinal bacteria (bacteria in the
gut) enter through the urethra and start multiplying in the bladder. Our defense system is
designed to keep such germs out, but sometimes they fail, and bacteria may take hold and
multiply into an infection.
The most common UTIs occur mainly in females and affect the urethra and bladder (males can
also become infected):
Cystitis (bladder infection) - refers to inflammation of the lining of the bladder. It usually occurs
when the normally sterile urethra and bladder (lower urinary tract) are infected by bacteria and
become irritated and inflamed.
Urethritis (infection of the urethra) - more common in females because the opening of the urethra
is closer to the anus (compared to males), making it easier for gastrointestinal bacteria to infect
the urethra.
Other possible urinary tract infections include:
Ureteritis (infection of the ureters) - the tubes from the kidneys to the bladder become infected.
Pyelonephritis (infection of the kidneys)
Diagnosing urinary tract infections
Lower urinary tract infection (Lower UTI) - a female patient with typical lower UTI symptoms will
not generally need to have the diagnosis confirmed with diagnostic tests, because lower UTI
causes a distinctive pattern of symptoms6. In other words, if the GP asks the patient questions

4. which are answered in a certain way, it is usually possible to make a reasonably accurate
diagnosis.
Further diagnostic tests may be needed if:
The patient is male - UTI is rare in men. Therefore, the doctor has to make sure that other
possible causes have been ruled out.
Upper UTI - if the doctor suspects upper urinary tract infection (upper UTI), which has a higher
risk of complications; a more careful assessment may be required of the urinary tract.
Pregnancy - if the patient is pregnant the doctor will probably order further tests.
Blood in urine - partly to rule out other illnesses and conditions, such as bladder cancer.
Vulnerable individuals - mainly patients with weakened immune systems, such as those with
diabetes, or possibly individuals receiving cancer therapy.
Diagnostic tests for UTI may include:
Urine test - to detect the presence of bacteria. A urine test will also help the doctor decide which
antibiotic to prescribe.
Intravenous urogram (IVU) - a special dye which shows up on an X-ray is injected into the patient.
The radiologist observes how the dye travels through the urinary system and problems are
detected.
Cytoscopy - the doctor inserts a long-thin instrument (a cystoscope) into the urethra in order to
look inside the urethra and bladder. There is a lense at the end of the cystoscope, allowing the
doctor to focus on the inner surfaces of the urinary tract. Some cystoscopes use flexible glass
fibers (optical fibers) that carry an image to a viewing piece. This procedure lasts from 5 to 10
minutes. A cytoscopy is effective in detecting bladder cancer.
What are the treatment options for urinary tract infection?
Treatment depends on whether it is an upper or lower urinary tract infection. Cases of lower UTI
and mild cases of upper UTI can be treated at home using antibiotics. Patients with more severe
upper UTI, as well as those with weakened immune systems may have to be hospitalized.
Lower urinary tract infection (lower UTI) treatment
Treatment typically involves taking an antibiotic course that lasts from 3 to 7 days. Those deemed
to have a higher risk of complications will be on antibiotics for longer.
Trimethoprim - an antibiotic commonly used for lower UTI cases. Side effects may include
nausea, vomiting, skin rash and itchy skin.
Painkillers - for abdominal pain the patient may take OTC (over-the-counter, no prescription
required) painkillers, such as ibuprofen.
Upper urinary tract infection (upper UTI) treatment
At home - this usually involves a longer course of antibiotics, between 7 and 14 days. Course
length is linked to complications risk.
Co-amoxiclav or ciprofloxacin - commonly prescribed unless the patient is pregnant. Pregnant
patients will probably have to take cephalexin. As they may cause drowsiness, patients should
not drive or operate heavy or complex machinery.
Fever and dehydration - the patient should consume plenty of liquids.
Painkillers - NSAIDs (non-steroidal anti-inflammatory drugs), such as ibuprofen or naproxen
should not be used as they may increase the risk of a kidney complication.
In hospital - the patient me be hospitalized if he or she:
is pregnant

5. is elderly
is vomiting
is in severe pain
is dehydrated
is urinating very infrequently
has a history of kidney disease
is HIV positive or has AIDS
has a kidney problem, such as a kidney stone
has cancer
has sickle-cell anemia
is having a recurrence of upper UTI
is undergoing radiotherapy or chemotherapy
In most cases the patient will receive fluids and possibly antibiotics through a drip. They will be
carefully monitored with regular urine and blood tests - these tests also help gauge how effective
the antibiotics have been.
Treatment for recurring urinary tract infections (recurring UTIs)
The patient may need further treatment to prevent urinary tract damage.
Experts say that recurring UTIs are probably due to the urethra becoming irritated after sexual
intercourse. Frequency of sexual intercourse in females is the strongest predictor of recurrent
urinary tract infections7. In such cases the patient will be asked to take an antibiotic tablet after
each episode of sexual intercourse.
Women with recurrent UTIs who use a diaphragm or spermicide-coated condoms as their main
contraception method should consider other forms of contraception, such as the pill.
Individuals whose recurring upper UTIs are not linked to sexual activity may be prescribed a lowdose antibiotic for daily use.
Methenamine hippurate is a medication which alters the chemical composition of urine, making it
a less attractive environment for bacteria. It is an alternative to antibiotics. Side effects may
include indigestion, itchy skin and skin rashes. Methenamine hippurate is less effective than
antibiotics in preventing upper UTI recurrences - therefore, it tends to be used solely by
individuals who either cannot or don't want to take antibiotics.
Recent developments on UTI treatment from MNT news
Stronger antibiotics are being overused for the treatment of urinary tract infection, researchers
from Oregon State University warned in October 2012. The increasing use of newer, expensive
and more powerful antibiotics for UTI treatment is fuelling the ever growing problem of antibiotic
resistance, they added. The scientists urge doctors and patients to opt for stronger medications
only "if it is critical".
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What are the possible complications of urinary tract infection (UTI)?
With prompt and proper treatment the chances of complications are tiny. However, untreated
UTIs can eventually lead to acute or chronic kidney infections, resulting in possibly permanent

6. kidney damage.
A pregnant woman whose UTI goes untreated has a significant risk of developing a kidney
infection. Kidney infections can trigger early labor and low birth weight8.
Recurrences - females who have at least 3 UTIs will probably continue having more of them.
Prevention Not all cases of UTI are preventable. However, there are some things we can do to
reduce the risk.
Cranberry juice or cranberry capsules - some studies have shown that drinking cranberry juice
helps reduce the risk of developing UTIs. For those with recurring UTIs stronger capsules are
recommended. Patients taking Warfarin should not take cranberry juice or capsules.
Constipation - can increase the risk of developing a UTI. Therefore, constipation should be
treated quickly, or prevented.
Urination - do not hold urine in; go whenever you feel like going. Bacteria can multiply rapidly
when urine stays in the bladder too long9.
Bottom wiping - after going to the toilet, wipe your bottom from front to back.
Genital hygiene - wash the genitals every day. Wash the genitals before having sex. Empty the
bladder after having sex.
Avoid irritating feminine products - such as deodorant sprays, douches, scented soaps and
powders may irritate the urethra.
Water - drink plenty of water throughout the day. Staying well hydrated helps flush out bacteria.
Recent developments on UTI prevention from MNT news
Scientists at the University of Stirling in Scotland found that cranberry extract is ineffective in
preventing urinary tract infections and bladder infections.
Cranberry powder can inhibit bacterium found in complicated urinary tract infections - scientists at
Montreal's McGill University, Canada, found that cranberry powder helps inhibit Proteus mirabilis,
a bacterium known to colonize in urinary catheters. Cranberry reduced the bacterium's production
of the enzyme urease, which is known to help infection to spread.

7. kidney damage.
A pregnant woman whose UTI goes untreated has a significant risk of developing a kidney
infection. Kidney infections can trigger early labor and low birth weight8.
Recurrences - females who have at least 3 UTIs will probably continue having more of them.
Prevention Not all cases of UTI are preventable. However, there are some things we can do to
reduce the risk.
Cranberry juice or cranberry capsules - some studies have shown that drinking cranberry juice
helps reduce the risk of developing UTIs. For those with recurring UTIs stronger capsules are
recommended. Patients taking Warfarin should not take cranberry juice or capsules.
Constipation - can increase the risk of developing a UTI. Therefore, constipation should be
treated quickly, or prevented.
Urination - do not hold urine in; go whenever you feel like going. Bacteria can multiply rapidly
when urine stays in the bladder too long9.
Bottom wiping - after going to the toilet, wipe your bottom from front to back.
Genital hygiene - wash the genitals every day. Wash the genitals before having sex. Empty the
bladder after having sex.
Avoid irritating feminine products - such as deodorant sprays, douches, scented soaps and
powders may irritate the urethra.
Water - drink plenty of water throughout the day. Staying well hydrated helps flush out bacteria.
Recent developments on UTI prevention from MNT news
Scientists at the University of Stirling in Scotland found that cranberry extract is ineffective in
preventing urinary tract infections and bladder infections.
Cranberry powder can inhibit bacterium found in complicated urinary tract infections - scientists at
Montreal's McGill University, Canada, found that cranberry powder helps inhibit Proteus mirabilis,
a bacterium known to colonize in urinary catheters. Cranberry reduced the bacterium's production
of the enzyme urease, which is known to help infection to spread.