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 urethra and the bladder.

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.

Not everyone with a urinary tract infection develops recognizable signs and symptoms, but most people have some.

In general, urinary tract infection signs and symptoms develop rapidly and can include:

• A strong, persistent urge to urinate
• A burning sensation when urinating
• Passing frequent, small amounts of urine
• Blood in the urine (hematuria) or cloudy, strong-smelling urine
• Bacteria in the urine (bacteriuria)

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.

If you have symptoms of a urinary infection, contact your doctor promptly.

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Female urinary system

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 multiply 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 the gastrointestinal bacteria make the short trip 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 simplex virus, gonorrhea and chlamydia, also are possible causes of urethritis.

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

• Being female. Half of all women will develop a urinary tract infection at some point during their lives, and many 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. Sexual intercourse can irritate the urethra, allowing germs to more easily travel through the urethra into the bladder.
• Using certain types of birth control. Women who use diaphragms for birth control also may be at higher risk, as are women who use spermicidal agents.
• Aging. After menopause, urinary tract infections may become more common because tissues of the vagina, urethra and the base of the bladder become thinner and more fragile due to loss of estrogen.
• Kidney stones or any other urinary obstruction.
• Diabetes and other chronic illnesses that may impair the immune system.
• Prolonged use of tubes (catheters) in the bladder.

Recurrent urinary tract infections
In women, the immune system may play a role in the risk of recurrent urinary tract infections. Bacteria can attach to cells in the urinary tract more easily in women lacking protective factors that normally allow the bladder to shed bacteria. More research is needed to determine the exact factors involved and how these factors can be manipulated to benefit women with frequent urinary tract infections.

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. Young children and older adults are at the greatest risk of kidney damage due to urinary tract infections because their symptoms are often overlooked or mistaken for other conditions. 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.

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 or 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 at any time that you don't understand something.

If your doctor suspects you have a urinary tract infection, he or she may ask you to turn in a urine sample to determine if pus, red blood cells or bacteria are present in your urine. To avoid potential contamination of the sample, you may be instructed to cleanse your genital area with an antiseptic pad and to collect the urine midstream.

Laboratory analysis of the urine (urinalysis), sometimes followed by a urine culture, can reveal whether you have an infection. Although no simple test can differentiate between an upper and lower urinary tract infection, the presence of fever and flank pain indicate that the infection likely involves your kidneys.

If your symptoms are typical of a urinary tract infection and you're generally in good health, antibiotics are the first line of treatment. Which drugs are prescribed and for how long depends on your health condition and the type of bacteria found in your urine.

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

• Amoxicillin (Amoxil, Trimox)
• Nitrofurantoin (Furadantin, Macrodantin)
• Ciprofloxacin (Cipro)
• Levofloxacin (Levaquin)
• Sulfamethoxazole-trimethoprim (Bactrim)

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 recommended 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 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 — bright blue or orange.

Recurrent infection
If you have recurrent urinary tract infections, your doctor may recommend a longer course of antibiotic treatment or a self-treatment program with short courses of antibiotics at the outset of your urinary symptoms. Home urine tests, in which you dip a test stick into a urine sample, are now available that are highly sensitive and may be helpful if you experience recurring infections.

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.

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 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 on your abdomen to minimize bladder pressure or discomfort.

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

• Drink plenty of liquids, especially water. Cranberry juice may have infection-fighting properties. 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.
• 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 as soon as possible 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.