Urinary Tract Infection (UTI)

Introduction

Have you ever had a burning sensation when urinating? Or have you felt pain or pressure in your lower abdomen or seen blood in your urine? These are the typical symptoms of a urinary tract infection (UTI), one of the most commonly occurring bacterial infections among men and women. Frequent and recurring UTIs can cause considerable physical discomfort and require repeated visits to a physician. But you can take steps to prevent UTIs. To learn more about how to prevent and treat UTIs, read on.

What is it?

Urine is normally sterile - free of bacteria, viruses, or fungi. A UTI occurs when bacteria from the digestive tract attach to the opening of the urethra, the opening through which urine passes out of the body, and begin to multiply. If bacteria continue to travel up the urinary tract, an infection of the kidneys, or pyelonephritis (pronounced "pie-low-nef-rye-tis"), can occur.

The urinary tract begins with the kidneys, includes the ureters and bladder, and ends at the urethra. A UTI can occur anywhere along the tract.

UTIs can be classified into three groups depending on:

The point in the urinary tract where they occur

Lower tract infections are UTIs that occur in the bladder, urethra, prostate (in men), or epididymis (also in men--a system of ducts that emerges from the testicle that holds sperm). An upper tract infection, or pyelonephritis, occurs in the kidney itself or the surrounding tissues. Pyelonephritis is generally more severe and requires a longer period of treatment than a lower tract infection.

Whether they are complicated

Uncomplicated UTIs have no complicating factors that make treatment more difficult, and a short period on an antibiotic usually clears them up. Complicated UTIs, by contrast, can be caused by bacteria that are more resistant to antibiotics, so they generally require a higher dose or longer duration of medication. Complicated UTIs generally occur in individuals who have structural or functional abnormalities of the urinary tract that interfere with the normal flow of urine and make the individual more susceptible to infections.

The following factors may put an individual at risk for developing a complicated UTI:

  • Being male
  • Being age 65 or older
  • Being pregnant
  • History of childhood UTIs
  • Recent treatment with an antibiotic
  • Recent visit to an emergency department in an urban hospital
  • Acquiring a urinary tract infection while hospitalized
  • Having a urinary catheter or recent instrumentation
  • Having an obstruction or stone within the urinary tract
  • Having an enlarged prostate
  • Having an altered mental state that reduces awareness of the need to void regularly
  • Having diabetes
  • Having a weakened immune system
  • Experiencing symptoms for more than 7 days before seeking treatment

Whether they recur frequently

Individuals who suffer from multiple UTIs (whether uncomplicated or complicated) in a short period of time may be experiencing recurrent UTIs. Recurrent UTIs are classified as either a reinfection or a relapse.

A reinfection is a UTI that occurs more than 2 weeks after antibiotic treatment of the original UTI is completed; it may be caused by the same bacteria as the original infection or a different one. The following are risk factors for reinfection:

  • Having frequent sexual intercourse
  • Use of a diaphragm or spermicide
  • History of 2 or more recurrent UTIs over a 6-month period or 3 or more UTIs over a year
  • Having the first UTI before age 15
  • Having a mother with a history of UTIs
  • Low estrogen level (in females)

A relapse is a UTI caused by the same bacteria as the original UTI that occurs within 2 weeks after the individual has completed antibiotic treatment. Relapse may be due to any of the following:

  • Antibiotic resistance (bacteria become resistant to an antibiotic so the drug no longer works)
  • Incorrect antibiotic use (for example, not taking the antibiotic exactly as prescribed, or discontinuing the antibiotic early rather than completing the full treatment as prescribed)
  • Wrong choice of antibiotic by the prescribing health care provider
  • Being at risk for a complicated UTI, as discussed earlier

    What causes it?

    The most common cause of uncomplicated UTIs is a bacterium called Escherichia coli, or E. coli. Staphylococcus saprophyticus and Pseudomonas aeruginosa are other bacteria that can cause UTIs. E. coli is also the most common cause of complicated UTIs, although many other organisms can be involved, for example, Enterococcus faecalis and Candida albicans, a fungus. Treatment for a UTI caused by a fungus would be different than that for a bacterial UTI.

    Bacteria cause infection in two ways: they release toxins that harm and kill body cells, and they provoke the immune system, leading to inflammation, which can in itself be harmful and uncomfortable for the affected individual.

    Bacteria release toxins that enter cells and kill them.

    In many cases, the body's own defense mechanisms are capable of repelling attacks by invading microorganisms such as bacteria and viruses. But if the bacteria multiplies to the point where the body's natural defenses cannot fight it, antibiotics may be needed to either destroy the bacteria completely or kill enough of them so the immune system can finish the job.

    Who has it?

    UTIs can occur in anyone, but the incidence varies by age and gender. Women generally experience UTIs more frequently than men and also have more recurrent infections. It is estimated that 50% of all women will suffer a symptomatic urinary tract infection (UTI) in their lifetime. Why women are more prone to UTIs than men is poorly understood. The anatomy of the female urinary tract is a likely factor. Men have a longer urethra, so bacteria have to travel much farther to cause a UTI. Also, the male prostate gland produces secretions that slow bacterial growth and may protect men from UTIs.

    Children are more prone to getting UTIs than adults because of structural or functional abnormalities of the urinary tract that often are recognized after the UTI diagnosis. Among children between 1 and 18 years of age, females get UTIs more frequently than males. Among individuals older than 65, UTIs are experienced equally by men and women. In addition, seniors usually experience different symptoms than younger individuals − possibly because they have a harder time building up an immune response. The increased incidence of UTIs in older adults is most likely due to catheter use, strokes (because of resultant functional incapacities), enlarged prostate and incontinence, which are all more common in the elderly.

    What are the risk factors?

    The following characteristics, medical conditions, and behaviors make it more likely that an individual will develop a UTI:

    Characteristics:

    • Being female
    • Being a child
    • Being elderly

    Medical conditions:

    • Obstruction of the urinary tract (for example, kidney stones or an enlarged prostate) can prevent urine from flowing through the tract and create a fertile environment for bacterial growth
    • Diabetes can cause sugar to be excreted in the urine, providing an excellent medium for bacterial growth
    • Pregnancy causes a natural change in the position of the bladder and hormonal changes, which may increase the risk for a UTI
    • Weakened immune system
    • Kidney disease reduces urine output, increasing the chance that bacteria in the urinary tract will thrive
    • Altered mental states (for example, dementia or Alzheimer's disease) reduce awareness of the need to urinate until the bladder is completely empty and can allow bacteria to thrive in the urinary tract
    • Spinal cord injury can reduce the ability to empty the bladder completely, allowing bacteria to thrive in the urinary tract
    • Catheterization (insertion and use of a catheter) often introduces bacteria into the urinary tract

    Behaviors:

    • Having frequent sexual intercourse allows bacteria to enter the urethra and migrate up the urinary tract
    • Using a diaphragm or spermicide for contraception changes the bacteria in the genital area and can destroy infection-fighting organisms in the urinary tract
    • Recent use of antibiotics can promote antibiotic resistance

    What are the symptoms?

    Infections of the lower urinary tract are generally accompanied by less severe symptoms than pyelonephritis (upper tract infection).

    Symptoms of lower urinary tract infections:

    • Painful urination
    • Increased urinary frequency/urgency
    • Awakening at night to urinate
    • Tenderness or heaviness in the lower abdomen
    • Blood in the urine
    • Foul smelling urine
    • Urine appears cloudy

    Symptoms of pyelonephritis:

    The following symptoms often occur in addition to those shown for lower tract infections:

    • Fever
    • Back pain, possibly one-sided
    • Abdominal pain
    • Nausea or vomiting
    • Tiredness or weakness

    Elderly individuals with a UTI may experience other symptoms in addition to those listed above, including altered mental status and changes in eating habits, perhaps because it is more difficult for them to build up an immune response to the infection.

    How is it treated?

    Whether an antibiotic is prescribed to treat a UTI and the choice of antibiotic will depend on several factors. These include the site of the infection (upper tract versus lower tract), the bacterium causing the infection, and any allergies the individual may have to antibiotics. Other considerations include the severity of the infection (complicated versus uncomplicated), the antibiotics used to treat previous infections, and the doctor's or health care provider's knowledge of any apparent antibiotic resistance.

    If you have experienced recurrent or frequent UTIs, your doctor may want you to continue taking antibiotics after you have finished treatment for an acute UTI. This is done to prevent future urinary infections. Recurrent lower tract infections may be prevented by taking low doses of Bactrim, trimethoprim, or nitrofurantoin for up to 6 months.

    Regardless of the drug chosen, it is important that you complete the antibiotic regimen that your health care provider has prescribed. Many individuals stop taking their medication when they feel better, a course of action that medical practitioners and pharmacists strongly discourage because it can allow an infection to recur with even greater severity within a short time frame. In addition, the bacteria in your system can develop resistance to the antibiotic, and you can spread the resistant bacteria to members of your family and community. If no other antibiotics are available to fight the bacteria, the consequences can be deadly for the infected individuals.

    Drugs used to treat Lower Tract Infections

    Preferred treatments for uncomplicated lower tract infections (usually 3 days of therapy):

    • Trimethoprim-sulfamethoxazole (Bactrim; Septra) -- Bacterial cells produce folic acid, a chemical necessary for their growth. Sulfamethoxazole kills the bacterium by interfering with the enzyme that helps form folic acid. The combination of a sulfamethoxazole with trimethoprim is effective because high levels of the drugs are achieved in the urinary tract and urine, which kills bacteria directly at the site of the infection.

    • Quinolones such as ciprofloxacin (Cipro), levofloxacin (Levaquin), and gatifloxacin (Tequin) -- Quinolones are effective in fighting most of the bacteria that cause UTI. This drug class works by interfering with an enzyme that allows bacteria to reproduce, thereby halting the growth of bacteria and eventually leading to their death. Quinolones are eliminated from the body by the kidney, so they go through the urinary tract, killing bacteria at the site of the infection.

    Alternative treatments (3-7 days of therapy) for uncomplicated lower tract infections:

    • Penicillins such as amoxicillin (Amoxil) and Augmentin -- Penicillins destroy the outer wall of bacteria, killing the bacteria but not harming the body's own cells. Historically, these antiobiotics have been effective in killing many of the bacteria that cause UTIs but more recently, bacterial resistance to these antibiotics is emerging.

    • Nitrofurantoin (Macrobid; Macrodantin) -- This drug is effective in killing many of the bacteria that cause UTIs. An added plus is that there have been few reports of bacterial resistance associated with its use.

    • Trimethoprim (Primsol) -- Patients who are allergic to sulfonamides (for example, Bactrim, Septra, and trimethoprim-sulfamethoxazole) may be treated with trimethoprim alone. High levels of the drug are achieved in the urinary tract and urine, which helps kill bacteria directly at the site of the infection.

    • Fosfomycin (Monurol) -- Fosfomycin, which is generally given as a single dose, is effective in treating organisms that cause uncomplicated UTIs.

    The antibiotics described above are also recommended for the treatment of complicated lower tract infections but are generally prescribed for 7 to 10 days. A urinary analgesic such as phenazopyridine (Pyridium) may also be prescribed to treat the pain associated with a complicated UTI.

    Drugs used to treat Pyelonephritis

    Drugs used to treat uncomplicated upper UTIs (need 7-14 days of therapy):

    • Quinolones
    • Trimethoprim-sulfamethoxazole
    • Penicillins

    Drugs used to treat complicated upper UTIs (need at least 14 days of therapy):

    • Quinolones
    • Extended spectrum penicillins, such as Augmentin
    • Aminoglycosides (gentamicin, tobramycin, amikacin)-Aminoglycosides, which have good coverage against Pseudomonas and other bacteria that are resistant to other antibiotics, are usually reserved for serious UTIs and used in combination with other antibiotics.

    For serious cases of pyelonephritis that require hospitalization, intravenous (IV) antibiotics are often needed. Hospitalization may also be required if the individual is pregnant or is experiencing nausea, vomiting, or dehydration.

    UTIs Caused by a Fungus

    If a fungus is found to be the cause of a UTI, then antibiotics will not work. Medications specifically designed to treat fungal infections such as fluconazole, amphotericin, or flucytosine are needed.

    Click on the drug class links below to learn more.

    Helping Yourself

    The good news is that urinary tract infections can usually be prevented by adopting a few personal habits and behaviors:

    • Decrease or eliminate the use of spermicides and diaphragms
    • Void immediately after intercourse
    • Drink plenty of water every day
    • Drink at least 8 ounces of cranberry juice every day or take a cranberry supplement (some persons report good results although there is currently no scientific evidence to definitively support this suggestion. The thought is that cranberry juice makes the urine more acidic which in turn makes it more difficult for bacteria to grow.)
    • After using the restroom, women should wipe from front to back so bacteria from the bowels don't get into the urinary tract
    • Urinate when you feel the urge; don't wait
    • Avoid tight fitting clothes
    • Wear cotton underware
    • Take showers instead of baths
    • Avoid bath oils, feminine hygiene sprays, douches, and powders
    • Change tampons and feminine napkins after each urination

    Over-the-counter preparations that may relieve your UTI symptoms and help you determine if you have a UTI include:

    • Products such as AZO and Uristat may lessen the pain associated with a UTI.
    • Urine-testing kits will help you determine if you have a UTI and should see your doctor.

    Be sure to contact your doctor at the onset of symptoms and before taking any of these products, which may reduce your symptoms but won't cure your infection. Your physician will probably want you to start an antibiotic. As always, carefully read product labels and heed all cautions. And as you should when you have any infection, get plenty of rest and drink lots of water.

    What is on the horizon?

    New drugs that are effective at treating resistant bacterial infections are a hot area of research and are continuously being studied in clinical trials. Another focus is improving existing drugs or modifying drug regimens in hopes of battling resistant bacteria. Also in development is a vaccine for women who suffer from recurrent UTIs. In addition, because many women with recurrent UTIs lack the normal protective bacterium Lactobacillus in the urinary tract, researchers are currently testing whether restoration of Lactobacillus will reduce the occurence of UTIs in these women.

    References

    Clinical Trials.gov. Urinary Tract Infection. Available at http://www.clinicaltrials.gov/ct2/results?term=urinary+tract+infection. Accessed December 2007.

    Coyle EA, Prince RA. Urinary tract infections and prostatitis. In: DiPiro JT, Talbert RL, Yee GC et al. (eds.). Pharmacotherapy: a pathophysiologic approach. 6th ed. New York: McGraw Hill; 2005: 2081-96.

    Fitzgerald MA. Urinary tract infection: providing the best care. Available at: http://www.medscape.com/viewprogram/1920. Accessed January 20, 2004 and December 2007.

    Krieger JN. Urinary tract infections: what's new? J Urol. 168(6):2351-8.

    National Kidney and Urologic Diseases Information Clearinghouse. Available at: http://www.kidney.niddk.nih.gov/index.htm. Accessed January 20, 2004 and December 2007.

    Nicolle LE. Managing acute uncomplicated cystitis in the era of antibiotic resistance. Available at: http://www.medscape.com/viewprogram/2634. Accessed January 20, 2004.

    Richard GA, Mathew CP, Kirstein JM, et al. Single-dose fluoroquinolone therapy of acute uncomplicated urinary tract infection in women: results from a randomized, double-blind, multicenter trial comparing single-dose to 3-day fluoroquinolone regimens. Urology. 59(3):334-339.

    Uehling DT, Hopkins WJ, Elkahwaji JE, et al. Phase 2 clinical trial of a vaginal mucosal vaccine for urinary tract infections. J Urol. 170(3):867-9.

    Urinary Tract Infection (UTI) Health Condition Last Updated: December 2007

    Note: The above information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist, or other healthcare professional. It is not intended to diagnose a health condition, but it can be used as a guide to help you decide if you should seek professional treatment or to help you learn more about your condition once it has been diagnosed.

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