Urinary tract infection - adults
A urinary tract infection, or UTI, is an infection of the urinary tract. The infection can occur at different points in the urinary tract including:
- 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
Bladder infection - adults; UTI - adults; Cystitis - bacterial - adults; Pyelonephritis - adults; Kidney infection - adults
Causes, incidence, and risk factors
Most urinary tract infections are caused by bacteria that enter the urethra and then the bladder. The infection most commonly develops in the bladder, but can spread to the kidneys. Most of the time, your body can get rid of these bacteria. However, certain conditions increase the risk of having UTIs.
Women tend to get them more often because their urethra is shorter and closer to the anus than in men. Because of this, women are more likely to get an infection after sexual activity or when using a diaphragm for birth control. Menopause also increases the risk of a UTI.
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The following also increase your chances of developing a UTI:
The symptoms of a bladder infection include:
or bloody urine, which may have a foul or strong odor
- Low fever in some people
- Pain or burning with urination
- Pressure or cramping in the lower abdomen 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
- Pain in the side, back, or groin
- Flushed, warm, or reddened skin
- Mental changes
(in the elderly, these symptoms often are the only signs of a UTI)
- Nausea and vomiting
- Very bad abdominal pain (sometimes)
Signs and tests
Most of the time you will need to provide a urine sample for the following tests:
. This test is done to look for white blood cells, red blood cells, bacteria, and to test chemicals, such as nitrites in the urine. This test can diagnose an infection most of the time.
- "Clean catch" urine culture
. This test may be done to identify the bacteria and determine the best antibiotic for treatment.
Blood tests such as CBC
and a blood culture
may be done as well.
You may also need the following tests to help rule out other problems in your urinary system:
Your health care provider must first decide if the infection is just in the bladder or has spread to the kidneys and how severe it is.
MILD BLADDER AND KIDNEY INFECTIONS
- Most of the time you will need to take antibiotic to prevent the infection from spreading 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.
- Be sure to finish all of the antibiotics, even if you feel better. If you do not finish the whole dose of medicine, the infection may return and be harder to treat later.
- Always drink plenty of water when you have a bladder or kidney infection.
- Commonly used antibiotics include trimethoprim-sulfamethoxazole, amoxicillin, Augmentin, doxycycline, and fluoroquinolones. (Tell your health care provider if you might be pregnant before taking these drugs.)
RECURRENT BLADDER INFECTIONS
Some women have repeated bladder infections. Your health care provider may suggest that you:
- Take a single dose of an antibiotic after sexual contact.
- Have a 3-day course of antibiotics at home to use if you develop an infection.
- Take a single, daily dose of an antibiotic to prevent infections.
MORE SEVERE KIDNEY INFECTIONS
You may need to go into the hospital if you are very sick and cannot take medicines by mouth or drink enough fluids. 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 do not go away with treatment or keep coming back. These are called chronic UTIs. If you have a chronic UTI, you may need stronger antibiotics or take medicine for a longer time.
You may need surgery if the infection is caused by a problem with the structure of the urinary tract.
Most urinary tract infections can be treated successfully. Bladder infection symptoms usually go away within 24 - 48 hours after treatment begins. If you have a kidney infection, it may take 1 week or longer for symptoms to go away.
- Life-threatening blood infection (sepsis
). The 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
Calling your health care provider
Contact your health care provider if you have symptoms of a UTI. Call right away if have signs of a possible kidney infection such as:
- Back or side pain
Also call if UTI symptoms come back shortly after you have been treated with antibiotics.
Diet and lifestyle changes
may help prevent some UTIs. After menopause, a woman may use estrogen cream around the vagina to reduce infections.
Nicolle LE. Urinary tract infection in adults. In: Taal MW, Chertow GM, Marsden PA et al. eds. Brenner and Rector's The Kidney. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 36.
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.
Jepson RG, Williams G, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database of Systematic Reviews. 2012;10:CD001321. DOI: 10.1002/14651858.CD001321.pub5.
Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.