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Urinary Tract Infections (UTIs) and Proteus Mirabilis

Updated on April 26, 2017
AliciaC profile image

Linda Crampton is a teacher with a first class honors degree in biology. She writes about human biology and the scientific basis of disease.

Proteus mirabilis and other bacteria live in the large intestine, which consists of the colon and the rectum. The rectum stores feces until it's ready to be released through the anus.
Proteus mirabilis and other bacteria live in the large intestine, which consists of the colon and the rectum. The rectum stores feces until it's ready to be released through the anus. | Source

Proteus mirabilis and UTIs

Proteus mirabilis is a rod-shaped bacterium that lives in the large intestine of many people. It's often harmless and forms a normal part of the gut flora, the useful community of microbes that shares our body with us. Under certain conditions, however, the bacterium can escape from the intestine and cause a urinary tract infection.

Bacteria are routinely shed in the feces. The feces leaves the intestine through an opening called the anus. In women, bacteria may pass from the anus to the nearby urethral opening. Once the microbes enter the urethra they may cause a urinary tract infection, or UTI.

Proteus infections are commonly associated with the formation of stones. The bacterium causes solid crystals to form in urine. Crystals join together to make stones. Small stones may leave the body on their own. Large ones may become trapped in the urinary tract and obstruct urine flow. They may also be very painful.

The Urinary Tract

The urinary system or tract and nearby blood vessels: 2 = kidney, 3 = renal pelvis, 4 = ureter, 5 = urinary bladder, 6 = urethra
The urinary system or tract and nearby blood vessels: 2 = kidney, 3 = renal pelvis, 4 = ureter, 5 = urinary bladder, 6 = urethra | Source

Structure and Function of the Urinary System

Structure
Function
Notes
Kidney
Produces urine by filtering blood and then changing the filtrate's composition by adding and removing substances
Each kidney contains around a million tiny filtering tubes called nephrons.
Renal pelvis
Drains urine from the kidneys
The renal pelvis is also called the pyelum.
Ureter
Transports urine from the renal pelvis to the urinary bladder
 
Urinary bladder
Stores urine temporarily and then sends it to the urethra
Stretch receptors in the bladder lining "tell" the brain that the bladder is full.
Urethra
Transports urine from the urinary bladder to the outside world
In a male the urethra transports sperm as well, although not at the same time as urine.
We have a kidney, a renal pelvis and a ureter on each side of our body (at the back of the abdomen). We have only one urinary bladder and urethra, which collect and transport urine from each kidney.

Causes of UTIs and Some Prevention Tips

In women, the anus is behind and close to the urethral opening. It's easy for bacteria to move from the anus to the urethra, which is why hygiene and careful toilet habits are so important. Health experts recommend that women wipe from front to back after defecation to reduce the chance of bacterial entry into the urethra. Bacteria can also enter the urethra from the opening to the reproductive tract, which is located between the anus and the urethral opening.

Women have a far higher incidence of UTIs than men, not only because of the location of their urethral opening but also because their urethra is shorter. A female's urethra is about one and a half inches in length while a male's is about eight inches long. In a female, the bacteria don't have far to travel to reach the urinary bladder and the rest of the urinary tract.

If some bacterial cells do manage to enter the urethra, the flow of urine may be able to flush them away. Urinating when necessary instead of retaining urine is one method used to reduce the chance of a UTI, as is drinking an adequate amount of water. Infections may develop if a large number of bacteria enter the urinary tract. In addition, people with structural abnormalities in the tract that tend to trap fluid are more likely to develop a UTI. In men, an enlarged prostate gland may exert pressure on the urinary tract and prevent adequate fluid flow, increasing the risk of an infection.

Structure of the kidney
Structure of the kidney | Source

Catheters and Urinary Tract Infections

People who have a catheter in the urethra have an increased risk of a UTI. A catheter is a medical device that drains urine from the body. It's a flexible tube that is placed in the urethra, positioned over the urethral opening or connected to the bladder to drain urine from the body. The urine enters a drainage bag. The catheter may be inserted temporarily or may be left in place (an indwelling catheter).

A catheter may be used in situations where it's difficult for a person to urinate normally. Two of these conditions are urinary incontinence and urinary retention. In urinary incontinence a person is unable to stop the release of urine from the bladder, while in urinary retention a person finds it difficult to release urine. A catheter is also used when there is spinal cord damage which prevents the normal process of urination or when a person is temporarily incapacitated in hospital.

Catheters are very useful devices. Unfortunately, the catheter surface may become coated with a film of bacteria that is hard to remove and becomes a continuous source of infection.

These are white blood cells in the urine of someone suffering from a urinary tract infection. The cells are part of the immune system.
These are white blood cells in the urine of someone suffering from a urinary tract infection. The cells are part of the immune system. | Source

Possible Symptoms of a Urinary Tract Infection

A person may have no symptoms of a urinary tract infection. However, there may be unpleasant symptoms, such as:

  • a strong and frequent urge to urinate
  • a burning pain during urination
  • pain or pressure in the lower abdomen
  • cloudy urine
  • blood in the urine
  • strong-smelling urine
  • a low-grade fever

If the infection spreads to the kidneys, a person may experience additional symptoms. These include a high fever, shaking and chills, back pain, nausea and vomiting.

Anyone with symptoms of a urinary tract infection should visit a doctor. An untreated infection may have serious consequences. These include kidney damage or failure and infection and inflammation in the bloodstream, which is known as sepsis.

Treatment and Prevention of UTIs in Women

Proteus mirabilis

Proteus mirabilis is an interesting, single-celled bacterium that exists in two different forms. These forms are known as swimmer cells and swarmer cells. Swimmer cells are rod-shaped and have eight to ten thin, whip-like extensions called flagella. The flagella enable the bacterium to move through a liquid. Each cell is one or two micrometers in length. A micrometer (µm) is a millionth of a meter or a thousandth of a millimeter.

When the swimmer cells settle on a surface their structure changes. They become much longer - up to eighty µm in length - and develop many more flagella. The flagella are very thin and may not be visible in photos or videos. The cells are now known as swarmer cells. The swarmer cells form an arrangement called a raft. In the raft, the flagella of neighboring cells become interwoven. The bacteria in the raft coordinate their movements and the raft as a whole moves rapidly over a surface, acting almost like a multicellular creature.

Swarming Proteus mirabilis

Bacteria and Urinary Tract Infections

Proteus UTIs are rare in people with normal urinary tracts, although they do occur. Escherichia coli urinary tract infections are far more frequent in this group of people. Proteus mirabilis infections are more common in people with structural abnormalities in their urinary tract that trap urine or in people who have a urinary catheter inserted in their body for a long period of time.

Proteus exhibits interesting behavior that may harm its host.

  • The bacterium contains an endotoxin in its cell wall. The toxin causes an inflammatory response in the host when it's released.
  • Fimbriae on the cell wall of the bacterium help it to adhere to the urinary tract lining and other surfaces.
  • The bacterium can form stationary films on top of surfaces, including urinary catheters. Bacteria in films (biofilms) are harder to eradicate than free-living bacteria because they secrete a slime that protects their bodies.
  • Proteus triggers the formation of mineral stones and crusts in the urinary tract of its host.

More Information About UTIs in Men and Women

Proteus mirabilis and Urinary Stones

Most people infected by Proteus mirabilis have stones in their urinary tract. Proteus releases an enzyme called urease. Urease acts on urea, a waste substance in urine. It converts the urea into ammonia, a basic (alkaline) substance that causes the pH to rise. The increased pH triggers calcium phosphate in urine to become solid and form apatite crystals. It also triggers magnesium ammonium phospate to soldify, forming struvite crystals.

Crystals aggregate to form stones, which may block the flow of urine. Bacteria of multiple species may enter crevices in the stones and become difficult to eradicate with antibiotics. The crystals may also form crusts on the inside and outside of catheters. Crusts inside a catheter can interfere with urine flow.

Stones not only act as a reservoir for bacteria but also increase the chance of an infection spreading up the urinary tract to the urinary bladder. Bacteria may enter the pelvis of the kidneys and even the kidneys themselves, where they form new stones. Cystitis (infection and inflammation of the urinary bladder) and pyelonephritis (infection of the renal pelvis and kidneys) are common in people who have stones in the urinary tract.

These are struvite stones from a dog's urinary bladder. The same stones form in humans during a Proteus mirabilis infection
These are struvite stones from a dog's urinary bladder. The same stones form in humans during a Proteus mirabilis infection | Source

Treatment of a UTI

Antibiotics are generally used to treat urinary tract infections. Catheters may be removed, at least until the infection has been cured. Once a person is better, a new catheter may be inserted if this is absolutely necessary. Stones may be broken up by a process called shockwave lithotripsy. Surgery may be necessary to remove large stones, however.

In the future, a vaccine may be created to prevent a Proteus mirabilis infection in the urinary tract. A vaccine would be very helpful, since the infection is common in certain groups of people and is sometimes challenging to treat.

References and Further Reading

© 2013 Linda Crampton

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    • billybuc profile image

      Bill Holland 4 years ago from Olympia, WA

      You continue to educate me and for that I am grateful.

    • AliciaC profile image
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      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you, Bill. I appreciate all your comments!

    • drbj profile image

      drbj and sherry 4 years ago from south Florida

      Fascinating examination, Alicia, of urinary tract infections. The swarming proteus mirabilis bacteria in the video almost seem to be creating a series of abstract art images. Did you notice?

    • AliciaC profile image
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      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you for the visit and comment, drbj. I found the swarming video fascinating, but I didn't think of it as art when I first saw it. You're right, though, the scenes do look like abstract art!

    • leahlefler profile image

      leahlefler 4 years ago from Western New York

      Oh, wow - the stones from the dog's bladder are so insanely big. I can't imagine having to pass one! I was prone to frequent bladder and kidney infections as a child (urinary reflux, grade V), but fortunately had surgery to prevent the backward flow of urine into my kidneys. I haven't had a bladder infection since - and fortunately have never had kidney stones!

    • AliciaC profile image
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      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, Leah. The stones from the dog do look big. They must have been painful! I'm glad the surgery helped you with your infections. Thanks for the visit!

    • b. Malin profile image

      b. Malin 4 years ago

      My Sister is prone to getting UTI, and yet I've never had one...Luck? As usual Alicia, a very Educational and most Informative read. I Never realized that Men can get them too...who knew? Once again, thanks for another well researched Hub.

    • AliciaC profile image
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      Linda Crampton 4 years ago from British Columbia, Canada

      Thanks for the comment, b. Malin. I appreciate your visit. Urinary tract infections are common in women. People who never get one are lucky!

    • Fossillady profile image

      Kathi 4 years ago from Saugatuck Michigan

      Hello Alicia, Drink lots more water, I have found that makes all the difference! Thanks for sharing very useful information. These are so common among us women and very painful!

    • AliciaC profile image
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      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, Kathi. Yes, drinking lots of water is very important! Thanks for the visit and the comment.

    • aviannovice profile image

      Deb Hirt 4 years ago from Stillwater, OK

      Great info, Alicia. When I was living elsewhere, a friend that I knew never drank water, always tea. He had stones a lot. Could that have been due to the fact that he never drank water?

    • AliciaC profile image
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      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, Deb. That's an interesting question. Some people claim that drinking lots of tea increases the risk of kidney stones due to the high level of oxalates that tea contains. I don't know if this has been proven scientifically, though. Thanks for the comment.

    • CraftytotheCore profile image

      CraftytotheCore 3 years ago

      Very interesting! I never knew there was so much to a UTI. Those are very painful.

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thanks for the visit, CraftytotheCore. I appreciate your comment!

    • profile image

      Christina 3 years ago

      Great article!

      I have an almost 6 year old who has no history of UTI until 4 months ago when he got his first. Lab confirmed the 3 uti's caused by proteus mirabilis.

      Renal ultrasound all perfect so we've been told likely cause is that he is not circumcised and doesn't drink much.

      I increased fluid intake, cut back fats etc and fingers crossed no further uti's (early days yet)

      Great article, thanks for the detail!

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thank you very much for the comment, Christina. Good luck with your son's UTI's. I hope they don't return!

    • LadyFiddler profile image

      Joanna Chandler 2 years ago from On planet Earth

      I some how wished they already had the vaccine. I am suffering with this said condition for about 1 1/2 yrs now it is awful. I have tried so many things, went to so many doctors , did so many tests and spend money like crazy. Yet i am truly suffering i urinate approximately on an average day 30 times sometimes more. I am not exaggerating the least i would go is about 20 times. I always have a toilet on my mind. I cannot hold the urine it burns my abdomen area if i really have to. I cannot go anywhere in peace least i need to use a rest room.

      I am trusting God to harken unto me and have mercy and heal me.

      Thanks for sharing.

    • AliciaC profile image
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      Linda Crampton 2 years ago from British Columbia, Canada

      I'm so sorry about your condition and the problems that you're experiencing, LadyFiddler. I hope new treatments are discovered very soon and that they improve your life. Best wishes to you. Thank you for commenting.

    • LadyFiddler profile image

      Joanna Chandler 2 years ago from On planet Earth

      Thank U Alicia ;)

    • PegCole17 profile image

      Peg Cole 20 months ago from Dallas, Texas

      Fascinating information about these common infections. Over the years I've had my share of UTIs and never really understood what caused them. Also, I learned a lot about kidney stones. Had to have one of those removed some years back. This makes so much sense as to why they form.

    • AliciaC profile image
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      Linda Crampton 20 months ago from British Columbia, Canada

      Hi, Peg. Thanks for the visit and the comment. UTIs are an interesting topic biologically, but they are very unpleasant to experience!

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