Urinary-Tract Infection Diagnosis

  • Diagnosis

    A urinary tract infection (UTI) is a bacterial infection of the urinary system, which consists of the kidneys, ureter, bladder, and urethra. Urinary tract infections are one of the most common causes of doctor visits, especially for women.

    There are several types of UTI, the most common being a bladder infection (cystitis). Urinary tract infections can also involve the ureters and kidneys; these infections are more difficult to treat. The most commonly seen UTIs are cystitis and kidney infections (pyelonephritis), with cystitis being 18 times more common.

    Most UTIs occur in women Table 01. The design of the female urinary tract makes it easy for bacteria to enter and cause an infection. It's estimated that 25% to 35% of women between the ages of 20 and 40 have had at least one UTI. Men are more likely to develop a UTI during infancy or after age 50. However, UTIs can affect anyone at any time of life.

    Table 1.  Development of UTIs by Gender and Age

    Age group Overall incidence Males vs. females
    Newborns/Infants 1% 1.5 to 1
    Preschoolers 1.5% to 3% 1 to 10
    School age 1.2% 1 to 30
    Reproductive years 3% to 5% 1 to 50
    Seniors (50+) 10% to 30% 1 to 1.5

    Bacteria are the most common cause of UTIs. In 85% of cases, the bacteria responsible for UTIs originate in one's own intestine or vagina. Vaginal bacteria, for example, may be introduced from condoms, or from the act of intercourse, which can push bacteria from outside the urinary system up into the urethra.

    While the bladder flushes out the majority of these bacteria during urination, sometimes bacteria can remain, leading to an infection. The most common bacterium to cause UTI is Escherichia coli.Other bacteria that can cause this infection include Proteus, Klebsiella, and Staphylococcus saprophyticus.

    Viruses, fungi, and parasites can also cause UTIs. The herpes simplex virus type 2 and fungal infections (i.e., yeast infections) can also cause UTIs. For example, the parasites that cause malaria can block the kidney's blood vessels and lead to UTIs. Similarly, a worm infection calledschistosomiasis can cause urinary infections. Infections caused by worms or parasites, however, tend to be rare in the U.S.

    Anatomical factors in both sexes can cause urinary infections. Any anatomical problem that obstructs the flow of urine can make it easier for bacteria to become trapped, leading to a UTI. An enlarged prostate, for example, is the most common reason why men over the age of 50 get UTIs. An uncircumcised penis can also trap bacteria, leading to a UTI. Similarly, an abnormality in women called a vesicovaginal fistula that links the bladder directly to the vagina can provide an easy route for bacterial infections.

    Physical changes during pregnancy can also predispose women to urinary tract infections. While the reasons for this are still unclear, one theory is that the hormonal changes of pregnancy dilate the urinary tract, impairing urine flow.

    A UTI is characterized by a number of symptoms Table 02. While it's possible to have a UTI without any symptoms, at least 10% to 20% of women experience symptoms of a UTI at some point in their lives.

    Feeling a repetitive, frequent, and urgent need to urinate, even if there's nothing to void, pain or burning during urination (dysuria), and waking from sleep due to the need to urinate (nocturia) are the most common symptoms produced by a UTI.

    A UTI that has travelled in the kidneys, causing a more serious infection known as pyelonephritis may cause more severe and more ominous symptoms, such as back pain, vomiting, and fever.

    Since children and the elderly are less likely to articulate symptoms of a UTI, parents should watch for changes in their child's physical and mental states—such as irritability, loss of appetite, or fever that may be signs of UTI. Caregivers of elderly people should look for signs of decreased urination, confusion, and irritability, particularly in elderly people who have dementia and cannot articulate their medical symptoms.

    Table 2.  Symptoms of a Urinary Tract Infection

    Symptoms in adults
    The need to urinate frequently
    Urgency, often followed by an inability to urinate
    Burning upon urination
    The need to get up in the night to go to the bathroom
    Pain, tenderness, or pressure in the area below the navel (the location of the bladder)
    Cloudy and/or foul-smelling urine
    Fever and/or chills
    Nausea and/or vomiting
    Pain in the upper back or side
    Blood in urine
    Symptoms in children
    Low-grade fever
    Irritability
    Abdominal pain
    Lack of appetite
    Strong-smelling urine
    Wetting the bed at night when one hasn't done so previously
    Blood in urine

    Women have a higher risk of developing a UTI than do men Table 03. The anatomy of the female genital and urinary tracts make women more prone to UTIs. In women, the tube through which urine travels (the urethra) is very short, and empties very close to the vaginal opening. Therefore, it is easy for bacteria from the vagina to travel to the urethra and then to the bladder, causing acute cystitis. By contrast, men have a much longer urethra, making it harder for the bacteria to travel to and settle in the bladder.

    Antibacterial prostatic secretions also lessen the likelihood that men will develop UTIs.

    Additionally, there's only a very narrow band of flesh (the perineum) between the anus and vagina in women. Therefore, it is easy for bacteria to move from the anus to the vagina, and from there to the urethra and the bladder.

    A man's risk for UTI increases with age. Older men are more likely to experience prostate-related problems that could lead to a UTI. For example, it is common for a man's prostate gland to enlarge around the age of 50. This enlargement can constrict the urethra, which then obstructs the flow of urine. If the flow is constricted, urine can pool in the bladder, creating an environment in which bacteria can multiply and cause an infection.

    Spinal cord abnormalities due to injury or genetic defects can foster UTIs. Abnormalities of the spinal cord, caused either by trauma or genetic defects, can cause UTIs in both men and women. For example, normal urinary control results from complex signals from the spinal cord and the overall nervous system. When those signals are disrupted, the bladder's ability to empty properly can be impaired, leading to urine back-up and infection. Patients with spinal cord injuries who have catheters in their bladder are at especially high risk of UTIs. Elderly people who have catheters in their bladders are also at higher risk.

    Table 3.  Risk Factor Checklist

    ?Women only
    Wiping back to front after urinating or after a bowel movement
    Not cleaning one's diaphragm properly, or handling it with unclean hands
    Not changing sanitary pads and/or tampons regularly
    Vaginal dryness
    Using spermicides and/or spermicide-coated condoms
    Anatomical issues
    Abnormalities that block the urinary system
    Spinal cord problems that prevent the bladder from emptying properly
    Prostate problems
    Lack of circumcision
    An abnormal connection between the bladder and vagina (vesicovaginal fistula) in women
    Other factors
    Diabetes
    Genetics
    Use of tubes, catheters, and other instruments in hospitalized patients
    Use of some laundry products

    Your doctor will evaluate your symptoms and run simple urine tests to diagnose a UTI. Your doctor will ask about your symptoms, and will try to determine other factors that may predispose you to a bladder infection. Your doctor will then perform a urine test for which you will have to provide a midstream sample. Bacteria from the sample will be cultured and identified in the lab. Once the bacterium is identified, the proper antibiotic can be prescribed.

    Various simple precautions can help prevent UTIs. To help flush your system of the bacteria that can cause UTIs, drink at least eight 8-oz. glasses of water daily, urinate frequently, and urinate after sex to void any bacteria transmitted during intercourse. You can also drink cranberry juice, which some some believe prevents E. coli from adhering to the bladder lining.

    Taking vitamin C supplements may also reduce your likelihood of getting a UTI by making your urine more acidic, which prevents bacterial growth.

    If you still have more than two bladder infections a year despite these precautions, discuss with your physician the possibility of taking low-dose antibiotics as a preventive measure. Your doctor may suggest that you take the medication regularly, or only after intercourse.

    Women should take additional precautions to avoid UTIs. Women should wipe from front to back after urinating or after a bowel movement to avoid sweeping bacteria into the urinary tract.

    Women should also take steps to avoid products or activities that could cause vaginal dryness or irriation. Such steps include using a water-soluble lubricant during sex, using effective alternatives to spermicides or spermicide-coated condoms for birth control, and avoiding vaginal care products, perfumed soap, and some laundry detergents.

    Finally, women should change their sanitary pads or tampons frequently while menstruating to keep the vaginal area as clean as possible.

    Discuss the pros and cons of home screening with your doctor. Home test kits designed to detect UTIs are available without a prescription, and can be useful for women who have recurrent infections. However, it's still wise to have your urine cultured to confirm exactly which bacterium is present, which in turn will allow your doctor to prescribe the most effective medicine.

  • Prevention and Screening

    Various simple precautions can help prevent UTIs. To help flush your system of the bacteria that can cause UTIs, drink at least eight 8-oz. glasses of water daily, urinate frequently, and urinate after sex to void any bacteria transmitted during intercourse. You can also drink cranberry juice, which some some believe prevents E. coli from adhering to the bladder lining.

    Taking vitamin C supplements may also reduce your likelihood of getting a UTI by making your urine more acidic, which prevents bacterial growth.

    If you still have more than two bladder infections a year despite these precautions, discuss with your physician the possibility of taking low-dose antibiotics as a preventive measure. Your doctor may suggest that you take the medication regularly, or only after intercourse.

    Women should take additional precautions to avoid UTIs. Women should wipe from front to back after urinating or after a bowel movement to avoid sweeping bacteria into the urinary tract.

    Women should also take steps to avoid products or activities that could cause vaginal dryness or irriation. Such steps include using a water-soluble lubricant during sex, using effective alternatives to spermicides or spermicide-coated condoms for birth control, and avoiding vaginal care products, perfumed soap, and some laundry detergents.

    Finally, women should change their sanitary pads or tampons frequently while menstruating to keep the vaginal area as clean as possible.

    Discuss the pros and cons of home screening with your doctor. Home test kits designed to detect UTIs are available without a prescription, and can be useful for women who have recurrent infections. However, it's still wise to have your urine cultured to confirm exactly which bacterium is present, which in turn will allow your doctor to prescribe the most effective medicine.

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