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Urinary tract infections are caused by microbes such as bacteria overcoming the body's defenses in the urinary tract. They can affect the kidneys, bladder, and the tubes that run between them.

They are one of the most common types of infection and account for around 8.1 million visits to a doctor every year.

The urinary tract can be divided into the upper urinary tract and the lower urinary tract. The upper urinary tract consists of the kidneys and the ureters, and the lower urinary tract consists of the bladder and the urethra.

Fast facts on urinary tract infections

Here are some key points about urinary tract infection. More detail and supporting information is in the main article.

  • Women have a lifetime risk of over 50 percent of developing a urinary tract infection (UTI).
  • Common symptoms include a strong, frequent urge to urinate and a painful and burning sensation when urinating.
  • A UTI is usually diagnosed based on symptoms and testing of a urine sample.
  • UTIs can be cured with 2 to 3 days of treatment.
  • Cranberry extracts do not treat UTIs but may help reduce the risk of recurrent UTI.

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Many people will experience UTIs in their lifetime.

The vast majority of urinary tract infections (UTIs) are caused by the bacterium Escherichia coli (E. coli), usually found in the digestive system. Chlamydia and mycoplasma bacteria can infect the urethra but not the bladder.

UTIs are given different names depending on where they occur. For example:

  • A bladder infection is called cystitis.
  • A urethra infection is called urethritis.
  • A kidney infection is called pyelonephritis.

The ureters are very rarely the site of infection.

Risk factors

Over 50 percent of all women will experience at least one UTI during their lifetime, with 20 to 30 percent experiencing recurrent UTIs.

Pregnant women are not more likely to develop a UTI than other women, but if one does occur, it is more likely to travel up to the kidneys. This is because changes in the body during pregnancy that affect the urinary tract.

As a UTI in pregnancy can prove dangerous for both maternal and infant health, most pregnant women are tested for the presence of bacteria in their urine, even if there are no symptoms, and treated with antibiotics to prevent spread.

People of any age and sex can develop a UTI. However, some people are more at risk than others. The following factors can increase the likelihood of developing a UTI:

  • sexual intercourse, especially if more frequent, intense, and with multiple or new partners
  • diabetes
  • poor personal hygiene
  • problems emptying the bladder completely
  • having a urinary catheter
  • bowel incontinence
  • blocked flow of urine
  • kidney stones
  • some forms of contraception
  • pregnancy
  • menopause
  • procedures involving the urinary tract
  • suppressed immune system
  • immobility for a long period
  • use of spermicides and tampons
  • heavy use of antibiotics, which can disrupt the natural flora of the bowel and urinary tract

The symptoms of a UTI can depend on age, gender, the presence of a catheter, and what part of the urinary tract has been infected.

Common symptoms of a UTI include:

  • strong and frequent urge to urinate
  • cloudy, bloody, or strong-smelling urine
  • pain or a burning sensation when urinating
  • nausea and vomiting
  • muscle aches and abdominal pains

People with catheters may only experience fever as a symptom, making diagnosis more difficult.

Acute pyelonephritis

Acute pyelonephritis is a sudden and severe kidney infection. If an individual develops this condition they could also experience upper back and side pain, high fever, shaking, chills, fatigue, and mental changes. It is considered an emergency and should be evaluated by a doctor immediately if suspected.

Cystitis

If a person has a bladder infection, they could also experience low fever, and pressure and cramping in the abdomen and lower back.

Complications

Most UTIs are not serious, but some can lead to serious problems, particularly with upper UTIs.

Recurrent or long-lasting kidney infections can cause permanent damage, and some sudden kidney infections can be life-threatening, particularly if bacteria enter the bloodstream in a condition known as septicemia.

They can also increase the risk of women delivering infants that are premature or have a low birth weight.

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Taking showers instead of baths can help prevent UTIs.

There are several measures that can be taken to reduce the risk of developing a UTI:

  • Drink lots of water and urinate frequently.
  • Avoid fluids such as alcohol and caffeine that can irritate the bladder.
  • Urinate shortly after sex.
  • Wipe from front to back after urinating and bowel movement.
  • Keep the genital area clean.
  • Showers are preferred to baths and avoid using oils.
  • Sanitary pads or menstrual cups are preferred to tampons. If you want to buy menstrual cups, then there is an excellent selection on Amazon with thousands of customer reviews.
  • Avoid using a diaphragm or spermicide for birth control.
  • Avoid using any perfumed products in the genital area.
  • Wear cotton underwear and loose-fitting clothing to keep the area around the urethra dry.

Individuals are advised to contact a doctor if they develop the symptoms of a UTI, especially if they have developed the symptoms of a potential kidney infection.

Diagnosis will usually be made after asking about the symptoms and testing a urine sample to assess the presence of white blood cells, red blood cells, and bacteria.

A method of collecting urine called "clean catch" is used. This requires that a person wash their genital area before providing a urine sample mid-flow. This helps to prevent bacteria from around the genital area getting caught in the sample.

If a person has recurrent UTIs, a doctor may request further diagnostic testing to determine if anatomical issues or functional issues are to blame. Such tests may include:

  • Diagnostic imaging: This involves assessing the urinary tract using ultrasound, CT and MRI scanning, radiation tracking, or X-rays.
  • Urodynamics: This procedure determines how well the urinary tract is storing and releasing urine.
  • Cystoscopy: This diagnostic exam allows the doctor to see inside the bladder and urethra with a camera lens, which inserted through the urethra through a long thin tube.

UTIs in men are rare. The incidence for men under the age of 50 years is between 5 and 8 men in every 10,000. The risk of infection increases with age.

When men contract a UTI, it will infect the same organs and areas as a UTI would in a woman. For men, however, the prostate is also at risk of infection.

A man with a circumcised penis is less likely to get a UTI that a man who has not undergone circumcision.

Treatment methods would be similar to those used to treat UTIs in women.

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Drinking plenty of water helps flush out UTIs and lowers the risk of future infection.

As UTIs are normally caused by bacteria, they are most commonly treated with antibiotics or antimicrobials.

The type of medication and length of treatment will depend on the symptoms and medical history of the individual.

The full course of treatment should always be completed for UTIs to make sure that the infection is fully clear, and to reduce the risk of antibiotic resistance. UTI symptoms can disappear before the infection has completely gone.

Drinking lots of fluids and frequently urinating are always recommended for people who have UTIs as this helps to flush out the bacteria. A variety of pain relief medications may be prescribed to alleviate pain. Applying a heating pad to the back or abdomen can also help.

An uncomplicated UTI is one that occurs in an otherwise healthy person with a normal clear urinary tract. These can usually be cured with 2 to 3 days of treatment.

A complicated UTI is one that occurs in a person who is weakened by another condition, such as pregnancy or heart transplant. Complicated UTIs tend to require longer periods of antibiotics, usually between 7 to 14 days.

To cure a UTI that is caused by problems within the urinary system, the underlying issue needs to be found and corrected. If left untreated, these infections can lead to kidney damage.

If the person is seriously ill, they may need to be admitted to a hospital to ensure that they take in sufficient fluids and receive the right medication. People may also need to go to the hospital if they are one of the following:

  • pregnant and are otherwise ill
  • older adults
  • people with cancer, diabetes, multiple sclerosis, spinal cord injury, or other medical problems
  • individuals with kidney stones or other changes in their urinary tract
  • recovering from recent urinary tract surgery

Recurrent infections in women

Women who have recurrent bladder infections may be advised to:

  • Take a single dose of an antibiotic after sexual contact
  • Take a single, daily dose of an antibiotic for at least 6 months
  • Take a 2-to-3-day course of an antibiotic if symptoms reappear
  • Undergo vaginal estrogen therapy if they have already had menopause

There are a number of suggested remedies that people with a UTI can try at home.

Drinking fluids and urinating frequently can help flush bacteria from the body, and using a heated pad for short periods can help to relieve discomfort.

It is also often said that cranberries and their extracts could treat UTI.

Cranberry extracts do not help treat existing UTIs but may help prevent their development.

This is because cranberries contain compounds called proanthocyanidins that prevent E. coli from sticking to the walls of the digestive and urinary tracts.

In a large meta-analysis, researchers found that women with recurrent UTIs who took cranberry over 12 months had a 35 percent reduction in infections.

Another large clinical trial found that 500 milligrams (mg) of cranberry extract taken daily for 6 months reduced the rate of UTI to the same extent as 100 mg of trimethoprim, an antibiotic, without posing a risk of antimicrobial resistance or super-infection in women with recurrent UTIs.

Cranberry extract tablets appear to be twice as effective as cranberry juice for preventing UTIs, which may be due in part to the sugar content of cranberry juice. Cranberry extracts also contain anthocyanins and salicylic acid. This may have a painkilling and anti-inflammatory effect that can help alleviate UTI symptoms.

The Society of Obstetricians and Gynaecologists of Canada recommend cranberry products to prevent recurrent UTIs, but not for use in active UTIs.

Cranberry extract tablets are available to purchase online. Speaking to a doctor is recommended, to determine the suitability of these tablets.

Changes in the bacterial balance of the genitourinary tract can increase the likelihood of colonization by organisms such as E. coli. Regular use of probiotics may help reduce the risk of UTIs, especially after a course of antibiotics.

Probiotics are available online as food products, such as yogurts, and supplements.

In particular, Bifidobacterium longum has shown an ability to prevent undesirable bacteria sticking to the walls of the intestinal tract, in addition to enhancing production of natural antibacterial chemicals and organic acids, thereby reducing the likelihood of UTI.

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