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Urinary tract infections (UTI)

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What are urinary tract infections?

A urinary tract infection (UTI) is an infection anywhere in the urinary tract. The urinary tract includes the kidneys, ureters, bladder and the urethra.

Urinary system and kidney anatomy. 

Causes

UTIs are more common in women than men because they have a shorter urethra, which makes it easier for micro-organisms to enter the urinary tract. The most common cause of a UTI is Escherichia coli (E. coli) bacteria, which are normally present in stools (feces). Other bacteria known to cause UTIs include Klebsiella, Proteus mirabilis, Pseudomonas, Streptococci, and Staphylococcus aureus. In adults, sexually-transmitted infections (STIs), such as chlamydia and gonorrhea, can also lead to UTIs.

UTIs can also be caused by Candida albicans, a fungus that commonly causes vaginal thrush, especially if it associated with the use of a urinary catheter.

Conditions that affect the flow of urine, such as kidney stones and ureteral reflux (in which urine travels back up the ureter towards the kidney), increase the chances of developing a UTI.

Risk factors

Risk factors for UTIs include:

  • Gender - females are more commonly affected than males;
  • Menopause;
  • Diabetes;
  • Kidney stones;
  • Bowel incontinence;
  • An enlarged prostate gland, narrow urethra, or anything blocking urine flow;
  • Having a urinary catheter;
  • Brain or nervous system problems that make it difficult to empty the bladder;
  • Pregnancy;
  • Atrophic vaginitis due to menopause;
  • Using certain contraceptives, such as spermicide or diaphragms;
  • Having multiple or new sexual partners;
  • Having had a UTI in the past 12 months, and;
  • Surgery involving the urinary tract.

Signs and symptoms

UTIs usually start in the bladder and/or prostate (in men), and can then spread to the kidneys, or even into the blood (sepsis or bacteremia). Symptoms of a UTI differ depending on whether it occurs in the bladder, prostate or kidney.

Symptoms of a bladder infection (cystitis) can include:

If the infection involves the prostate (prostatitis) in a male, symptoms can include:

Symptoms of a kidney infection (pyelonephritis) include:

Methods for diagnosis

Urine culture

A urine culture is the gold standard for diagnosing UTIs. A diagnosis is usually made on the basis of urine culture results and the presence of symptoms. Since this test can take a few days to produce results, your doctor may prescribe antibiotic treatment before the test results are in.

Your doctor may also perform a rapid test (known as a dipstick urine test) to check whether there are any features of a UTI. This test is often used only to support suspicion of a UTI, and it cannot be entirely relied upon for a diagnosis.

Urine collection

Urine is often collected in what is called a 'clean catch' or 'midstream' specimen. This requires a small amount of urine to first be passed before urine is collected in a sample container.

Another collection technique involves inserting a catheter into the urethra to draw urine directly from the bladder. This can be helpful in people who have no bladder control, or who are unable to follow instructions to give a urine sample.

Urine testing can provide a rapid and reliable diagnosis of an infection such as a UTI. 

Other tests

Imaging tests, including ultrasound, computerized tomography (CT) scan and cystoscopy, may be performed if you have recurrent infections, or if any abnormalities in the kidneys, bladder or urethra are suspected. A digital rectal exam may also be performed if infection of the prostate is suspected in men.

Types of treatment

UTIs generally require treatment to prevent the infection spreading to the kidneys (pyelonephritis) or into the blood (sepsis). Bacterial infections are treated with antibiotics, usually taken as tablets, for several days. It is important to also drink plenty of water during a UTI, to help flush micro-organisms from the urinary tract. Symptoms improve within a day or two, but it is important to finish the full course of antibiotics as prescribed by your doctor, otherwise the infection may return.

You may also be advised to take medication to help with the burning sensation during urination. These medications help to neutralize the pH balance of the urine so that it does not burn the inflamed urinary tract. Depending on the type you take, the color of your urine may change from orange or red. These medications are not meant to be taken for more than two days, unless advised by your doctor.

Kidney infection

Kidney infection is usually treated with intravenous antibiotics. If you are otherwise well, you may be allowed to stay at home and continue on oral antibiotics after the initial intravenous dose. However, if symptoms worsen or you are not improving, it is important you promptly see you doctor. If you are pregnant, or have severe pain and a high fever, you will likely be hospitalized and given intravenous antibiotics and fluids. When you improve, you will be able to go home and switch to oral antibiotics

Fungal infection

Infection of the upper urinary tract or widespread (systemic) infection with Candida albicans, a type of fungus, is treated with antifungal medication. Antifungal medication is not normally recommended if the infection is only associated with a catheter and not causing any symptoms. However, a change of the catheter is recommended.

Potential complications

Complications are rare when UTIs are treated promptly. However, if left untreated, UTIs can cause sepsis, kidney abscess, swelling of the kidneys, and reduced kidney function and failure. These complications are also more likely in recurrent infections and the risk of sepsis is higher in people who are immunocompromised due to conditions, such as HIV/AIDS, or treatments such as chemotherapy. It is relatively common for UTIs to return and the use of preventative antibiotics is controversial. Preventative antibiotics, if used, are generally reserved for people who have very frequent or severe UTIs. The risks of antibiotic resistance and side effects need to be balanced against the benefits of preventing the infections.

Prognosis

Most UTIs are successfully treated with antibiotics. It is important to finish the prescribed course of antibiotics to prevent the return of infection.

Prevention

Drinking plenty of fluids and urinating soon after sex may help reduce your risk. Women who get recurrent UTIs as a result of using spermicide or diaphragms can use alternative types of contraception.

References

  1. Urine Is Not Sterile: Use of Enhanced Urine Culture Techniques To Detect Resident Bacterial Flora in the Adult Female Bladder. Accessed 4 August 2014 from link here
  2. Evidence of Uncultivated Bacteria in the Adult Female Bladder. Accessed 14 August 2014 from link here
  3. Evidence of Uncultivated Bacteria in the Adult Female Bladder. Accessed 14 August 2014 from link here
  4. Murtagh J. MD. Murtaghs General Practice. (5th ed.).
  5. Urinary tract infection - adults - National Library of Medicine - PubMed Health. Accessed 12 August 2014 from link here
  6. Urinary tract infections in adolescents and adults. Accessed 12 August 2014 from link here
  7. Urine Is Not Sterile: Use of Enhanced Urine Culture Techniques To Detect Resident Bacterial Flora in the Adult Female Bladder. Accessed 13 August 2014 from link here

10 Most frequently asked questions (FAQs)

What are urinary tract infections?
A urinary tract infection occurs when bacteria or other pathogens cause infection of the urinary system. Most of these infections are caused by E. coli bacteria.
What are the symptoms of urinary tract infections?
The symptoms of urinary tract infections vary according to whether the bladder, kidneys or prostate are affected. When the bladder is infected, symptoms include a strong or foul urine odor, cloudy urine, frequent urination, low fever, blood in the urine, burning pain while urinating, or pain in the lower back or pelvis. When the kidneys are infected, symptoms include chills, shaking, fever, fatigue, reddened skin, pain in the side, back or groin and confusion or behavioral changes, especially in the elderly. If just the prostate is involved, there tend to be flu-like symptoms of fever and lower backache.
What causes urinary tract infections?
Urinary tract infections are caused by bacteria and sometime fungi. The most common type of bacteria is a type of E. coli, although other bacteria, such as the one that causes chlamydia, can also cause the infection.
How are urinary tract infections diagnosed?
Although you will often be given antibiotics based on your symptoms, a urine culture will often be performed to confirm diagnosis of a urinary tract infection. The reason antibiotics are provided before the culture results is that the urine culture results can take a couple of days to arrive, and if a urinary tract infection is suspected, it is better to start treatment early in order to avoid complications. Certain scans and procedures may also be required if an underlying medical condition is thought to be the cause of the infection.
How are urinary tract infections treated?
Urinary tract infections are treated with antibiotics, taken for a period ranging anywhere from a day to a week to several weeks, depending on the infection.
Can urinary tract infections be prevented?
It is possible that frequent urination and urinating soon after sex can reduce your risk of urinary tract infections. Contraception other than diaphragms and spermicides are advised for women as these can increase the risk of a urinary tract infection.
Will urinary tract infections keep returning?
Urinary tract infections can relapse or return if you do not complete your course of antibiotics, or return to them at a later date. Preventative antibiotics are sometimes prescribed to help prevent recurrent infections, but their use is controversial as it can contribute to microbial resistance to antibiotics.
Are there different types of urinary tract infections?
Urinary tract infections can be caused by a range of different bacteria, but most commonly are caused by a type of E. coli. Infection of different areas of the urinary system such as the bladder, kidneys and prostate all give rise to slightly different symptoms.
What is the outcome for urinary tract infections?
With antibiotic treatment, the outcome for most urinary tract infections is good. Symptoms usually go away within a couple of days, although the full course of antibiotics will need to be continued and finished after symptoms have gone, otherwise the infection may return.
Are urinary tract infection serious?
Left untreated, urinary tract infections can be serious. Complications of urinary tract infections include infection of the bloodstream (sepsis), abscess formation in the kidneys and even kidney damage and failure.

Related topics

Bladder cancer

Bladder cancer is the name for cancers that arise in the tissues of the bladder, the organ that stores urine before it is expelled from the body during urination. Abnormal cells can form a tumour, affect urination and spread throughout the body.

Urinary tract infections (UTI) in children

Younger children often have vague symptoms when they have a urinary tract infection (UTI). These include fever, vomiting, poor feeding and irritability. In older children, there may be frequent urination, burning sensations when urinating, fatigue, or abdominal pain. UTIs in children may require prompt treatment with antibiotics to prevent damage to the kidneys.

Kidney stones

Stones can form in the kidney and move into other parts of the urinary tract. Large kidney stones can get stuck causing extreme pain, blood in the urine and/or kidney failure. Often, ultrasound waves can be used to break up kidney stones.

Bedwetting

Bedwetting is a common condition where toilet-trained children accidentally urinate during their sleep. It is not a sign of laziness, naughtiness, or any emotional immaturity. It is important not to blame or shame the child over this behaviour, which is not under the child's control. Strategies are available to treat this condition.

About this article

Title: Urinary tract infections (UTI)

Author: Jonathan Meddings BMedLabSc (Hons)

First Published: 24 Oct 2014

Last reviewed: 17 Jan 2022

Category: Information on Urinary tract infections (UTI)

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