The urinary tract is a system in the body for removing waste and excess water.1 It consists of the bladder, the kidneys, the ureters and the urethra. The kidneys filter the blood and remove waste and surplus water to form urine, which then travels down the ureters and is stored in the bladder until it is ready to be passed through the urethra (urination).
The opening of the urethra is the end of the penis in males and at the front of the vagina in females.
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.
Urinary tract infections are caused by microbes such as bacteria overcoming the body's defenses in the urinary tract. Urinary tract infections can have different names referring to the different parts of the urinary tract:
- Bladder infection = Cystitis
- Urethra infection = Urethritis
- Kidney infection = Pyelonephritis.
The ureters are very rarely the site of infection.
Contents of this article:
You will also see introductions at the end of some sections to any recent developments that have been covered by MNT's news stories. Also look out for links to information about related conditions.
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.
- 40-50% of women have at least one urinary tract infection (UTI) during their lifetime. 20-30% have a recurrent UTI (2 infections in 6 months, or more than 3 infections a year).
- Women have a lifetime risk of over 50% of developing a urinary tract infection.
- The majority of urinary tract infections are caused by the E. Coli bacterium.
- Common symptoms include a strong, frequent urge to urinate and a painful and burning sensation when urinating.
- Urinary tract infection is usually diagnosed based on symptoms and testing of a urine sample.
- Urinary tract infections are commonly treated with antibiotics, although antibiotic use is also a risk factor for UTI.
- Having diabetes increases the risk of UTI, as do the use of tampons and spermicides, frequent or intense sex, and sex with a new partner and/or multiple partners.
- Uncomplicated urinary tract infections can be cured with 2-3 days of treatment.
- Cranberry extracts do not treat UTIs, but may help reduce the risk of recurrent UTI.
- Most young women with urinary tract infections have uncomplicated urinary tract infections.
- Men with urinary tract infections should be presumed to have complicated urinary tract infections until it can be proven otherwise.
- In severe cases, seriously ill patients with urinary tract infections may need to be hospitalized.
- UTIs do not appear to be more common in pregnancy, but are more likely to lead to kidney infection and can be very dangerous for maternal and infant health.
What is a urinary tract infection?
A urinary tract infection (UTI) is an infection of any part of the urinary system.2 Most infections involve the lower urinary tract.
The urinary tract is comprised of the bladder, kidneys, ureters and urethra.
Urinary tract infections are the second most common type of infection in the body and account for around 8.1 million visits to health care providers each year.1
Over 50% of all women will experience at least one UTI during their lifetime, with 20-30% experiencing recurrent UTI.11 Women are more likely to develop UTIs than men, due to anatomical differences; the urethra is shorter in women than in men, and it is closer to the anus, making it more likely that bacteria are transferred to the bladder.
With each UTI, the risk that a woman or man will have another UTI increases.
Pregnant women are not more likely to develop a UTI than other women, but if one does occur in a pregnant woman then it is more likely to travel up to the kidneys due to anatomical changes affecting the urinary tract in pregnancy.
As a UTI in pregnancy can prove dangerous for both maternal and infant health, most pregnant women are tested for bacteriuria, even if asymptomatic, and treated with prophylactic antibiotics.
Most UTIs are not serious, but some can lead to serious problems, particularly with upper urinary tract infections. Recurrent or long-lasting kidney infections (chronic) can cause permanent damage, and some sudden kidney infections (acute) can be life-threatening, particularly if septicemia (bacteria entering the bloodstream) occurs.
They can also increase the risk of women delivering low birth weight or premature infants.3
Causes of urinary tract infections
Urinary tract infections are caused when microbes manage to get past the body's natural defenses.
The vast majority of UTI cases 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.
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:145
- Sexual intercourse (especially if more frequent, intense and with multiple or new partners)
- Poor personal hygiene
- Problems emptying the bladder completely
- Having a urinary catheter
- Bowel incontinence
- Blocked flow of urine
- Kidney stones
- Some forms of contraception
- 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).
Recent developments on urinary tract infection causes from MNT news
The World Health Organization have published their first global review of antimicrobial resistance, including antibiotic resistance - with data covering 114 countries - and conclude that it poses a serious threat to public health for everybody, everywhere.
Symptoms of urinary tract infections146
The symptoms of a urinary tract infection can depend on age, gender, the presence of a catheter and what part of the urinary tract has been infected.
Abdominal pains are a common symptom of urinary tract infections.
Common symptoms of urinary tract infection include:
- Strong and frequent urge to urinate
- Cloudy, bloody or strong smelling urine
- Pain or burning sensation when urinating
- Nausea and vomiting
- Muscle aches and abdominal pains.
People with catheters may only experience fever as a symptom, making diagnosis problematic.
If a person has a kidney infection, they could also experience upper back and side pain, high fever, shaking, chills, fatigue and mental changes.
If a person has a bladder infection, they could also experience low fever, and pressure and cramping in the abdomen and lower back.
On the next page we look at tests and diagnosis for urinary tract infections as well as treatment information and how to prevent them occurring.