Urinary tract infection

Definition

A urinary tract infection is an infection that begins in your urinary system. Your urinary system is composed of the kidneys, ureters, bladder and urethra. Any part of your urinary system can become infected, but most infections involve the lower urinary tract — the bladder and the urethra.

Women are at greater risk of developing a urinary tract infection than are men. A urinary tract infection limited to your bladder can be painful and annoying. However, serious consequences can occur if a urinary tract infection spreads to your kidneys.

Antibiotics are the typical treatment for a urinary tract infection. But you can take steps to reduce your chance of getting a urinary tract infection in the first place.

Symptoms

Urinary tract infections don't always cause signs and symptoms, but when they do they can include:

  • A strong, persistent urge to urinate
  • A burning sensation when urinating
  • Passing frequent, small amounts of urine
  • Urine that appears cloudy
  • Urine that appears bright pink or cola colored — a sign of blood in the urine
  • Strong-smelling urine
  • Pelvic pain, in women
  • Rectal pain, in men

Types of urinary tract infection
Each type of urinary tract infection may result in more-specific signs and symptoms, depending on which part of your urinary tract is infected.

Part of urinary tract affectedSigns and symptoms
Kidneys (acute pyelonephritis)
  • Upper back and side (flank) pain
  • High fever
  • Shaking and chills
  • Nausea
  • Vomiting
Bladder (cystitis)
  • Pelvic pressure
  • Lower abdomen discomfort
  • Frequent, painful urination
  • Blood in urine
Urethra (urethritis)
  • Burning with urination








When to see a doctor
Make an appointment with your doctor if you have signs and symptoms that worry you.

Causes

The urinary system is composed of the kidneys, ureters, bladder and urethra. All play a role in removing waste from your body. Urinary tract infections typically occur when bacteria enter the urinary tract through the urethra and begin to multiply in the bladder. Although the urinary system is designed to keep out such microscopic invaders, the defenses sometimes fail. When that happens, bacteria may take hold and grow into a full-blown infection in the urinary tract.

The most common urinary tract infections occur mainly in women and affect the bladder and urethra.

  • Infection of the bladder (cystitis) is usually caused by Escherichia coli (E. coli), a species of bacteria commonly found in the gastrointestinal tract. Sexual intercourse may lead to cystitis, but you don't have to be sexually active to develop it. All women are susceptible to cystitis because of their anatomy — specifically, the close proximity of the urethra to the anus and the short distance from the urethral opening to the bladder.
  • Infection of the urethra (urethritis) can occur when gastrointestinal bacteria spread from the anus to the urethra. In addition, because of the female urethra's proximity to the vagina, sexually transmitted diseases (STDs), such as herpes, gonorrhea and chlamydia, also are possible causes of urethritis.

Risk factors

Some people appear to be more likely than are others to develop urinary tract infections. Risk factors include:

  • Being female. Urinary tract infections are very common in women, and many women will experience more than one. A key reason is their anatomy. Women have a shorter urethra, which cuts down on the distance bacteria must travel to reach the bladder.
  • Being sexually active. Women who are sexually active tend to have more urinary tract infections than women who aren't sexually active.
  • Using certain types of birth control. Women who use diaphragms for birth control also may be at higher risk, as may women who use spermicidal agents.
  • Undergoing menopause. After menopause, urinary tract infections may become more common because the lack of estrogen causes changes in the urinary tract that make it more vulnerable to infection.
  • Having urinary tract abnormalities. Babies born with urinary tract abnormalities that don't allow urine to leave the body or cause urine to back up in the urethra have an increased risk of urinary tract infections.
  • Having blockages in the urinary tract. Kidney stones or an enlarged prostate can trap urine in the bladder and increase the risk of urinary tract infection.
  • Having a suppressed immune system. Diabetes and other diseases that impair the immune system — the body's defense against germs — can increase the risk of urinary tract infections.
  • Using a catheter to urinate. People who can't urinate on their own and use a tube (catheter) to urinate have an increased risk of urinary tract infections. This may include people who are hospitalized, people with neurological problems that make it difficult to control their ability to urinate and people who are paralyzed.

Complications

When treated promptly and properly, urinary tract infections rarely lead to complications. But left untreated, a urinary tract infection can become something more serious than merely a set of uncomfortable symptoms.

Untreated urinary tract infections can lead to acute or chronic kidney infections (pyelonephritis), which could permanently damage your kidneys. Urinary tract infections may be overlooked or mistaken for other conditions in older adults. Young children also have an increased risk of kidney infections. Pregnant women who have urinary tract infections may have an increased risk of delivering low birth weight or premature infants.

Women who experience three or more urinary tract infections are likely to continue experiencing them.

Preparing for your appointment

Most urinary tract infections are treated by your family doctor or a general practitioner. However, when recurrences are frequent or a kidney infection becomes chronic, you'll likely be referred to a doctor who specializes in urinary disorders (urologist) or kidney disorders (nephrologist) for an evaluation to determine if urologic abnormalities may be causing the infections.

What you can do
Before your appointment, make a list of medications or supplements you're taking and any allergies you have. Having this information helps your doctor select the best treatment.

Write down questions to ask your doctor. Some basic questions include:

  • What kind of tests do I need?
  • Can I do anything to prevent a urinary tract infection?
  • What signs and symptoms should I watch out for?
  • What do the results of my urine test mean?
  • Do I need to take medicine?
  • Are there any special instructions for taking the medicine?
  • What can I do if I keep getting urinary tract infections?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment any time you don't understand something.

Tests and diagnosis

Tests and procedures used to diagnose urinary tract infections include:

  • Analyzing a urine sample.Your doctor may ask you to turn in a urine sample that will be analyzed in a laboratory to determine if pus, red blood cells or bacteria are present. To avoid potential contamination of the sample, you may be instructed to first wipe your genital area with an antiseptic pad and to collect the urine midstream.
  • Growing urinary tract bacteria in a lab. Laboratory analysis of the urine is sometimes followed by a urine culture — a test that uses your urine sample to grow bacteria in a lab. This test tells your doctor what bacteria are causing your infection and which medications will be most effective.
  • Creating images of your urinary tract. If your doctor suspects that an abnormality in your urinary tract is causing frequent infections, you may undergo tests to create images of your urinary tract using ultrasound or computerized tomography (CT). Another test called an intravenous urinary pyelogram uses X-rays to create images. During this test, a dye is injected into a vein in your arm and X-rays are taken of your urinary tract. The dye highlights your bladder and urethra and allows your doctor to determine if you have any abnormalities that slow urine from leaving your body.
  • Using a scope to see inside your bladder. If you have recurrent urinary tract infections, your doctor may use a long, thin tube with a lens (cystoscope) to see inside your urethra and bladder. The cystoscope is inserted in your urethra and passed through to your bladder. This procedure is called cystoscopy.

Treatment and drugs

Antibiotics are typically used to treat urinary tract infections. Which drugs are prescribed and for how long depend on your health condition and the type of bacterium found in your urine.

Simple infection
Drugs commonly recommended for simple urinary tract infections include:

  • Sulfamethoxazole-trimethoprim (Bactrim, Septra, others)
  • Amoxicillin (Larotid, Moxatag, others)
  • Nitrofurantoin (Furadantin, Macrodantin, others)
  • Ampicillin
  • Ciprofloxacin (Cipro)
  • Levofloxacin (Levaquin)

Usually, symptoms clear up within a few days of treatment. But you may need to continue antibiotics for a week or more. Take the entire course of antibiotics prescribed by your doctor to ensure that the infection is completely eradicated.

For an uncomplicated urinary tract infection that occurs when you're otherwise healthy, your doctor may recommend a shorter course of treatment, such as taking an antibiotic for one to three days. But whether this short course of treatment is adequate to treat your infection depends on your particular symptoms and medical history.

Your doctor may also prescribe a pain medication (analgesic) that numbs your bladder and urethra to relieve burning while urinating. One common side effect of urinary tract analgesics is discolored urine — orange or red.

Frequent infections
If you experience frequent urinary tract infections, your doctor may recommend a longer course of antibiotic treatment or a program with short courses of antibiotics at the outset of your urinary symptoms.

Your doctor may also recommend taking home urine tests, in which you dip a test stick into a urine sample.

For infections related to sexual activity, your doctor may recommend taking a single dose of antibiotic after sexual intercourse.

If you're postmenopausal, your doctor may recommend vaginal estrogen therapy to minimize your chance of recurrent urinary tract infections.

Severe infection
For severe urinary tract infections, hospitalization and treatment with intravenous antibiotics may be necessary.

Alternative medicine

Cranberry juice
There's some indication, though it hasn't been proved, that cranberry juice may have infection-fighting properties and drinking cranberry juice daily may help prevent urinary tract infections. Studies have shown the greatest effect in women who have frequent urinary tract infections. Studies involving children and older adults have had mixed results.

It's not clear how much cranberry juice you'd need to drink or how often you'd need to drink the juice to have an effect.

If you enjoy drinking cranberry juice and feel it helps you prevent urinary tract infections, there's little harm in continuing to drink it. For most people, drinking cranberry juice is safe — some people report an upset stomach or diarrhea.

However, don't drink cranberry juice if you're taking the blood-thinning medication warfarin. Possible interactions between cranberry juice and warfarin may lead to bleeding.

Lifestyle and home remedies

Urinary tract infections can be painful, but you can take steps to ease your discomfort until antibiotics clear the infection. Follow these tips:

  • Drink plenty of water to dilute your urine and help flush out bacteria.
  • Avoid drinks that may irritate your bladder. Avoid coffee, alcohol, and soft drinks containing citrus juices and caffeine until your infection has cleared. They can irritate your bladder and tend to aggravate your frequent or urgent need to urinate.
  • Use a heating pad. Apply a warm, but not hot, heating pad to your abdomen to minimize bladder pressure or discomfort.

Prevention

Take these steps to reduce your risk of urinary tract infections:

  • 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.
  • Wipe from front to back. Doing so after urinating and after a bowel movement helps prevent bacteria in the anal region from spreading to the vagina and urethra.
  • Empty your bladder soon after intercourse. Also, drink a full glass of water to help flush bacteria.
  • Avoid potentially irritating feminine products. Using deodorant sprays or other feminine products, such as douches and powders, in the genital area can irritate the urethra.

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