A urinary tract infection, or UTI, is an infection that can happen anywhere along the urinary tract. Urinary tract infections have different names, depending on what part of the urinary tract is infected.

• Bladder -- an infection in the bladder is also called cystitis or a bladder infection.
• Kidneys -- an infection of one or both kidneys is called pyelonephritis or a kidney infection.
• Ureters -- the tubes that take urine from each kidney to the bladder are only rarely the site of infection.
• Urethra -- an infection of the tube that empties urine from the bladder to the outside is called urethritis.

See also:

• Cystitis - noninfectious
• Interstitial cystitis
• Urethritis
• Urinary tract infection - children

Bladder infection - adults; UTI - adults; Cystitis - bacterial - adults; Pyelonephritis - adults; Kidney infection - adults

The symptoms of a bladder infection include:

• Cloudy or bloody urine, which may have a foul or strong odor
• Low fever (not everyone will have a fever)
• Pain or burning with urination
• Pressure or cramping in the lower abdomen (usually middle) or back
• Strong need to urinate often, even right after the bladder has been emptied

If the infection spreads to your kidneys, symptoms may include:

• Chills and shaking or night sweats
• Fatigue and a general ill feeling
• Fever above 101 degrees Fahrenheit
• Flank (side), back, or groin pain
• Flushed, warm, or reddened skin
• Mental changes or confusion (in the elderly, these symptoms often are the only signs of a UTI)
• Nausea and vomiting
• Severe abdominal pain (sometimes)

A urine sample is usually collected to perform the following tests:

• Urinalysis is done to look for white blood cells, red blood cells, bacteria, and to test for certain chemicals, such as nitrites in the urine. Most of the time, your doctor or nurse can diagnose an infection using a urinalysis.
• Urine culture - clean catch may be done to identify the bacteria in the urine to make sure the correct antibiotic is being used for treatment.

CBC and a blood culture may be done.

The following tests may be done to help rule out problems in your urinary system that might lead to infection or make a UTI harder to treat:

• CT scan of the abdomen
• Intravenous pyelogram (IVP)
• Kidney scan
• Kidney ultrasound
• Voiding cystourethrogram

Your doctor must first decide whether you have a mild or simple bladder or kidney infection or an infection that is more serious.

MILD BLADDER AND KIDNEY INFECTIONS

Antibiotics taken by mouth are usually recommended because there is a risk that the infection can spread to the kidneys.

• For a simple bladder infection, you will take antibiotics for 3 days (women) or 7 - 14 days (men). For a bladder infection with complications -- such as pregnancy or diabetes, OR a mild kidney infection -- you will usually take antibiotics for 7 - 14 days.
• It is important that you finish all of the antibiotics, even if you feel better. If you do not finish all of your antibiotics, the infection could return and may be harder to treat later.

Commonly used antibiotics include trimethoprim-sulfamethoxazole, amoxicillin, Augmentin, doxycycline, and fluoroquinolones. Your doctor will also want to know whether you could be pregnant.

Your doctor may also recommend drugs to relieve the burning pain and urgent need to urinate. Phenazopyridine hydrochloride (Pyridium) is the most common of this type of drug. You will still need to take antibiotics.

Everyone with a bladder or kidney infection should drink plenty of fluids.

Some women have repeat or recurrent bladder infections. Your doctor may suggest several different ways of treating these.

• Taking a single dose of an antibiotic after sexual contact may prevent these infections, which occur after sexual activity.
• Having a 3-day course of antibiotics at home to use for infections diagnosed based on your symptoms may work for some women.
• Some women may also try taking a single, daily dose of an antibiotic to prevent infections.

See also: Catheter-associated UTI

MORE SEVERE KIDNEY INFECTIONS

If you are very sick and cannot take medicines by mouth or drink enough fluids, you may be admitted to the hospital. You may also be admitted to the hospital if you:

• Are elderly
• Have kidney stones or changes in the anatomy of your urinary tract
• Have recently had urinary tract surgery
• Have cancer, diabetes, multiple sclerosis, spinal cord injury, or other medical problems
• Are pregnant and have a fever or are otherwise ill

At the hospital, you will receive fluids and antibiotics through a vein.

Some people have urinary tract infections that keep coming back or that do not go away with treatment. Such infections are called chronic UTIs. If you have a chronic UTI, you may need antibiotics for many months, or stronger antibiotics.

If a structural (anatomical) problem is causing the infection, surgery may be recommended.

A urinary tract infection is uncomfortable, but treatment is usually successful. Symptoms of a bladder infection usually disappear within 24 - 48 hours after treatment begins. If you have a kidney infection, it may take 1 week or longer for your symptoms to go away.

• Life-threatening blood infection (sepsis) - risk is greater among the young, very old adults, and those whose bodies cannot fight infections (for example, due to HIV or cancer chemotherapy)
• Kidney damage or scarring
• Kidney infection

Contact your health care provider if you have symptoms of a UTI. Call right away if the following symptoms develop:

• Back or side pain
• Chills
• Fever
• Vomiting

These may be signs of a possible kidney infection.

Also call if you have already been diagnosed with a UTI and the symptoms come back shortly after treatment with antibiotics.

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Little P, Moore MV, Turner S, et al. Effectiveness of five different approaches in management of urinary tract infection: randomised controlled trial. BMJ. 2010 Feb 5;340:c199. doi: 10.1136/bmj.c199.

Gupta K, Hooton TM, Naber KG, et al. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: A 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis. 2011 Mar;52(5):e103-20.

Hooton TM, Bradley SF, Cardenas DD, et al. Diagnosis, prevention, and treatment of catheter-associated urinary tract infection in adults: 2009 International Clinical Practice Guidelines from the Infectious Diseases Society of America. Clin Infect Dis. 2010 Mar 1;50(5):625-63.