About Urinary Tract Infections

A UTI is an infection in the urinary tract. Infections are caused by microbes—organisms too small to be seen without a microscope—including fungi, viruses, and bacteria. Bacteria are the most common cause of urinary tract infections. Normally, bacteria that enter the urinary tract are rapidly removed by the body before they cause symptoms. However, sometimes bacteria overcome the body’s natural defenses and cause infection. An infection in the urethra is called urethritis. A bladder infection is called cystitis. Bacteria may travel up the ureters to multiply and infect the kidneys. A kidney infection is called pyelonephritis.

• What is the urinary tract?

  The urinary tract is the body’s drainage system for removing wastes and extra water. The urinary tract includes two kidneys, two ureters, a bladder, and a urethra. The kidneys are a pair of bean-shaped organs, each about the size of a fist and located below the ribs, one on each side of the spine, toward the middle of the back. Every minute, a person’s kidneys filter about 3 ounces of blood, removing wastes and extra water. The wastes and extra water make up the 1 to 2 quarts of urine a person produces each day. The urine travels from the kidneys down two narrow tubes called the ureters. The urine is then stored in a balloon like organ called the bladder and emptied through the urethra, a tube at the bottom of the bladder.

  When the bladder empties, a muscle called the sphincter relaxes and urine flows out of the body through the urethra. The opening of the urethra is at the end of the penis in males and in front of the vagina in females.

• What causes UTIs?

  Most urinary tract infections are caused by bacteria that live in the bowel. Urinary tract infections can occur when bacteria enter the urinary tract through the urethra and multiply to cause urinary symptoms. The bacteria Escherichia coli (E. coli) causes the vast majority of UTIs. Microbes called Chlamydia and Mycoplasma can infect the urethra and reproductive system but not the bladder. Chlamydia and Mycoplasma infections may be sexually transmitted and require treatment of sexual partners.

  The urinary tract has several systems to prevent infection. The points where the ureters attach to the bladder act like one-way valves to prevent urine from backing up toward the kidneys, and urination washes microbes out of the body. In men, the prostate gland produces secretions that slow bacterial growth. In both sexes, immune defenses also prevent infection. But despite these safeguards, infections still occur. Certain bacteria have a strong ability to attach themselves to the lining of the urinary tract.

• How common are UTIs in adults?

  Urinary tract infections are the second most common type of infection in the body in Minneapolis, accounting for about 8.1 million visits to health care providers each year. Women are especially prone to UTIs for anatomical reasons. One factor is that a woman’s urethra is shorter, allowing bacteria quicker access to the bladder. Also, a woman’s urethral opening is near sources of bacteria from the anus and vagina. For women, the lifetime risk of having a UTI is greater than 50 percent. UTIs in men are not as common as in women but can be serious when they occur.

• Who is at risk for a UTI?

  Although everyone has some risk, some people are more prone to getting UTIs than others. People with spinal cord injuries or other nerve damage around the bladder have difficulty emptying their bladder completely, allowing bacteria to grow in the urine that stays in the bladder. Anyone with an abnormality of the urinary tract that obstructs the flow of urine—a kidney stone or enlarged prostate, for example—is at risk for a UTI. People with diabetes or problems with the body’s natural defense system are more likely to get UTIs.

  Sexual activity can move microbes from the bowel or vaginal cavity to the urethral opening. If these microbes have special characteristics that allow them to live in the urinary tract, it is harder for the body to remove them quickly enough to prevent infection. Following sexual intercourse, most women have a significant number of bacteria in their urine, but the body normally clears them within 24 hours. However, some forms of birth control increase the risk of UTI. In some women, certain spermicides may irritate the skin, increasing the risk of bacteria invading surrounding tissues. Using a diaphragm may slow urinary flow and allow bacteria to multiply. Condom use is also associated with increased risk of UTIs, possibly because of the increased trauma that occurs to the vagina during sexual activity. Using spermicides with diaphragms and condoms can increase risk even further.

  Another common source of infection is catheters, or tubes, placed in the urethra and bladder. Catheters interfere with the body’s ability to clear microbes from the urinary tract. Bacteria travel through or around the catheter and establish a place where they can thrive within the bladder. A person who cannot urinate in the normal way or who is unconscious or critically ill often needs a catheter for more than a few days. The Infectious Diseases Society of America recommends using catheters for the shortest time possible to reduce the risk of a UTI.

  Men are less likely than women to have a first UTI. But once a man has a UTI, he is likely to have another because bacteria can hide deep inside prostate tissue. Anyone who has diabetes or a problem that makes it hard to urinate may have repeat infections.

• Are UTIs serious?

  Most UTIs are not serious, but some infections can lead to serious problems, such as kidney infections. This is why it is important to see a urologist who is specially trained to treat this condition. Chronic kidney infections—infections that recur or last a long time—can cause permanent damage, including kidney scars, poor kidney function, high blood pressure, and other problems. Some acute kidney infections—infections that develop suddenly—can be life threatening, especially if the bacteria enter the bloodstream, a condition called septicemia.

• What are the signs and symptoms of a UTI?

  Symptoms of a UTI vary by age, gender, and whether a catheter is present. Urinary tract infection symptoms typically include a frequent and intense urge to urinate and a painful, burning feeling in the bladder or urethra during urination. The amount of urine may be very small. Older women and men are more likely to be tired, shaky, and weak and have muscle aches and abdominal pain. Urine may look cloudy, dark, or bloody or have a foul smell. In a person with a catheter, the only symptom may be fever that cannot be attributed to any other cause. Normally, UTIs do not cause fever if they are in the bladder. A fever may mean the infection has reached the kidneys or has penetrated the prostate. Other symptoms of a kidney infection include pain in the back or side below the ribs, nausea, vomiting, and blood in the urine.

• How are UTIs diagnosed?

  To find out whether a person has a UTI, our urologists will ask about urinary symptoms and then test a sample of urine for the presence of bacteria and white blood cells, which are produced by the body to fight infection. If a person has recurrent UTIs, the urologist may order some additional tests.

  Additional testing which may help evaluate for recurrent UTIs include: 

  • Kidney and bladder ultrasound. Ultrasound uses a device, called a transducer that bounces safe, painless sound waves off organs to create an image of their structure. The procedure is performed in our offices by a specially trained technician, and the images are interpreted by a radiologist—a doctor who specializes in medical imaging; anesthesia is not needed. The images can show abnormalities in the kidneys and bladder. However, this test cannot reveal all important urinary abnormalities or measure how well the kidneys work.

   

  • Voiding cystourethrogram. This test is an x-ray image of the bladder and urethra taken while the bladder is full and during urination, also called voiding. As the person lies on the x-ray table, a health care provider inserts the tip of a thin, flexible tube called a catheter through the urethra into the bladder. The bladder and urethra are filled with a special dye called contrast medium, to make the structures clearly visible on the x-ray images. The x rays are taken from various angles while the bladder is full of contrast medium. The catheter is then removed and x-ray images are taken during urination. The procedure is performed in a health care provider’s office, outpatient center, or hospital by an x-ray technician. The technician is supervised by a radiologist while the images are taken. The radiologist then interprets the images. Anesthesia is not needed, but light sedation may be used for some people. This test can show abnormalities of the inside of the urethra and bladder. The test can also determine whether the flow of urine is normal when the bladder empties.

   

  • Computerized tomography (CT) scan. CT scans use a combination of x rays and computer technology to create three-dimensional (3-D) images. A CT scan may include the injection of contrast medium. CT scans require the person to lie on a table that slides into a tunnel-shaped device where the x rays are taken. The procedure is performed in an outpatient center or hospital by an x-ray technician, and the images are interpreted by a radiologist; anesthesia is not needed. CT scans can provide clearer, more detailed images to help the health care provider understand the problem.

   

  • Magnetic resonance imaging (MRI). MRI machines use radio waves and magnets to produce detailed pictures of the body’s internal organs and soft tissues without using x rays. An MRI may include an injection of contrast medium. With most MRI machines, the person lies on a table that slides into a tunnel-shaped device that may be open ended or closed at one end; some newer machines are designed to allow the person to lie in a more open space. The procedure is performed in an outpatient center or hospital by a specially trained technician, and the images are interpreted by a radiologist; anesthesia is not needed though light sedation may be used for people with a fear of confined spaces. Like CT scans, MRIs can provide clearer, more detailed images.

   

  • Urodynamics. Urodynamic testing is any procedure that looks at how well the bladder, sphincters, and urethra are storing and releasing urine. Most urodynamic tests focus on the bladder’s ability to hold urine and empty steadily and completely. Urodynamic tests can also show whether the bladder is having abnormal contractions that cause leakage.

   

  • Cystoscopy. Cystoscopy is a procedure that uses a tube-like instrument to look inside the urethra and bladder. Cystoscopy may be used to look for swelling, redness, and other signs of infection.
• How can recurrent UTIs be prevented?

  Changing some daily habits may help a person prevent recurrent UTIs.

  • Eating, Diet, and Nutrition. Drinking lots of fluid can help flush bacteria from the system. Water is best. Most people should try for six to eight, 8-ounce glasses a day or such that the color of the urine is light yellow. A person who has kidney failure should not drink this much fluid. A health care provider should be consulted to learn how much fluid is healthy.

   

  • Urination Habits. A person should urinate often and when the urge arises. Bacteria can grow when urine stays in the bladder too long. Women should urinate shortly after sex to flush away bacteria that might have entered the urethra during sex. Wiping from front to back after urinating and after a bowel movement helps prevent bacteria in the anal region from spreading to the vagina and urethra. Avoid potentially irritating feminine products or deodorant sprays, such as douches and powders, in the genital area as they can irritate the urethra.

   

  • Clothing. Cotton underwear and loose-fitting clothes should be worn, so air can keep the area around the urethra dry. Tight-fitting jeans and nylon underwear should be avoided because they can trap moisture and help bacteria grow.

   

  • Drink plenty of liquids, especially water. Drinking water helps dilute your urine and ensures that you’ll urinate more frequently — allowing bacteria to be flushed from your urinary tract before an infection can begin.

   

  • Cranberry Supplements. Although studies are not conclusive that cranberry clearly prevents all UTIs, it is likely not harmful. Supplements can be purchased over the counter or online. The FDA does not regulate such medication.

   

  • Vaginal health. Female hormone estrogen may protect against urinary tract infections in postmenopausal women by improving the body’s defense mechanisms.  In postmenopausal women, the low levels of estrogen are thought to have a role in recurrent infections by causing changes in the urinary tract that make it more vulnerable to infection. It is thought that using estrogen supplements, in the form of a low-dose cream, suppository, or ring applied in the vaginal area, may prevent recurring UTIs.

   

  • Antibiotic Prophylaxis. Following discussion of the risks, benefits, and alternatives, physicians may prescribe antibiotic prophylaxis to decrease the risk of future UTIs for a short period of time.