A urinary tract infection (UTI) is an infection involving the kidneys, ureters, bladder, or urethra. These are the structures that urine passes through before being eliminated from the body.
The kidneys are a pair of small organs that lie on either side of the spine at about waist level. They have several important functions in the body, including removing waste and excess water from the blood and eliminating them as urine. These functions make them important in the regulation of blood pressure. Kidneys are also very sensitive to changes in blood sugar levels and blood pressure and electrolyte balance. Both diabetes and hypertension can cause damage to these organs.
Any part of this system can become infected. As a rule, the farther up in the urinary tract the infection is located, the more serious it is. The upper urinary tract is composed of the kidneys and ureters. Infection in the upper urinary tract generally affects the kidneys (pyelonephritis), which can cause fever, chills, nausea, vomiting, and other severe symptoms. The lower urinary tract consists of the bladder and the urethra. Infection in the lower urinary tract can affect the urethra (urethritis) or the bladder (cystitis).
The urine is normally sterile. An infection occurs when bacteria get into the urine and begin to grow. The bacterial infection usually starts at the opening of the urethra where the urine leaves the body and moves upward into the urinary tract.
The culprit in at least 90% of uncomplicated infections is a type of bacteria called Escherichia coli, better known as E. coli. These bacteria normally live in the bowel (colon) and around the anus. They can move from the area around the anus to the opening of the urethra. The two most common causes of this are improper wiping and sexual intercourse.
Usually, the act of emptying the bladder (urinating) flushes the bacteria out of the urethra. If there are too many bacteria, urinating may not stop their spread.
- People with conditions that block (obstruct) the urinary tract, such as kidney stones.
- People with medical conditions that cause incomplete bladder emptying (for example, spinal cord injury).
- Pregnant women.
- Postmenopausal women. Decreased circulating estrogen makes the urinary tract more vulnerable to a UTI.
- People with suppressed immune systems. Examples of situations in which the immune system is suppressed are HIV/AIDS and diabetes. People who take immunosuppressant medications such as chemotherapy for cancer also are at increased risk.
- Women who are sexually active. Sexual intercourse can introduce larger numbers of bacteria into the bladder. Urinating after intercourse seems to decrease the likelihood of developing a urinary tract infection.
- Women who use a diaphragm for birth control.
- Men with an enlarged prostate. Prostatitis or obstruction of the urethra by an enlarged prostate can lead to incomplete bladder emptying, thus increasing the risk of infection. This is most common in older men.
- Young children. Young children have trouble wiping themselves and washing their hands well after a bowel movement. Poor hygiene has been linked to an increased frequency of urinary tract infections in children. Urinary tract infection in children can be (but is not always) a sign of an abnormality in the urinary tract, usually a partial blockage. An example is a condition in which urine moves backward from the bladder up the ureters (vesicoureteral reflux).
- Hospitalized patients or nursing-home residents. Many of these individuals are catheterized for long periods and are thus vulnerable to infection of the urinary tract. Catheterization means that a thin tube (catheter) is placed in the urethra to drain urine from the bladder. This is done for people who have problems urinating or cannot reach a toilet on their own.
Symptoms of Urinary Tract Infection
- pain or burning during urination.
- more frequent urination (or waking up at night to urinate, sometimes referred to as nocturia); often with only a small amount of urine.
- the sensation of having to urinate urgently.
- Cloudy, bad-smelling, or bloody urine.
- Lower abdominal pain or pelvic pressure or pain.
- Mild fever, chills, and “just not feeling well” (malaise).
- Nausea and vomiting.
- Pain in the back or side, usually on only one side at about waist level
In newborns, infants, children, and elderly people, the classic symptoms of a urinary tract infection may not be present.
Treatment of Urinary Tracts Infection
The usual treatment for both simple and complicated urinary tract infections is antibiotics. The type of antibiotic and duration of treatment depend on the circumstances. Examples of common antibiotics used in treatment include, but are not limited to, amoxicillin, sulfamethoxazole/trimethoprim (Bactrim), ciprofloxacin, nitrofurantoin (Macrobid), and many others. Your health-care provider will chose the appropriate medication for your condition and the specific causative organisms.
A complicated, acute infection may require treatment for several weeks.
A person may be hospitalized if he or she has symptoms of pyelonephritis and any of the following:
- Appear very ill.
- Are pregnant.
- Have not gotten better with outpatient antibiotic treatment.
- Have underlying diseases that compromise the immune system (diabetes is one example) or are taking immunosuppressive medication.
- Are unable to keep anything in the stomach because of nausea or vomiting.
- Had previous kidney disease, especially pyelonephritis, within the last 30 days.
- Have a device such as a urinary catheter in place.
- Have kidney stones.
Prevention of Urinary Tract Infection
You can prevent urinary tract infections by improving your personal and toilet hygeine. Women and girls should wipe from front to back (not back to front) after bowel movements. This helps prevent bacteria from the anus entering the urethra.
You should empty the bladder regularly and completely, especially after sexual intercourse.
Drinking plenty of fluids, especially water and cranberry juice, has been shown to help prevent urinary tract infections.