What Are Urinary tract infection?

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 rarely the only site of infection.
Urethra : An infection of the tube that empties urine from the bladder to the outside is called urethritis.
 

Causes

Most UTIs 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.

The following also increase your chances of developing a UTI:

Diabetes
Advanced age and conditions that affect personal care habits (such as Alzheimer disease and delirium)
Problems emptying the bladder completely
Having a urinary catheter
Bowel incontinence
Enlarged prostate, narrowed urethra, or anything that blocks the flow of urine
Kidney stones
Staying still (immobile) for a long period of time (for example, while you are recovering from a hip fracture)
Pregnancy
Surgery or other procedure involving the urinary tract

Symptoms

The symptoms of a bladder infection include:

Cloudy or bloody urine, which may have a foul or strong odor
Low fever in some people
Pain or burning with urination
Strong need to urinate often, even right after the bladder has been emptied
Pressure or cramping in the lower abdomen or back

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°F (38.3°C)
Pain in the side, back, or groin
Flushed, warm, or reddened skin
Mental changes or confusion (in older people, these symptoms often are the only signs of a UTI)
Nausea and vomiting
Very bad abdominal pain (sometimes)