What Is a Urinary Tract Infection?

A bacterial urinary tract infection (UTI) is the most common kind of infection affecting the urinary tract. Urine, or pee, is the fluid that is filtered out of the bloodstream by the kidneys. Urine contains salts and waste products, but it doesn't normally contain bacteria. When bacteria get into the bladder or kidney and multiply in the urine, a UTI can result.
There are three main types of UTI. Bacteria that infect only the urethra (the short tube that delivers urine from the bladder to the outside of the body) cause urethritis (pronounced: yur-ih-threye-tis). Bacteria can also cause a bladder infection, which is called cystitis (pronounced: sis-tie-tis). Another, more serious, kind of UTI is infection of the kidney itself, known as pyelonephritis (pronounced: pie-low-nih-fry-tis). With this type of UTI, a person often has back pain, high fever, and vomiting.
The most common type of UTI, the bladder infection, causes mostly just discomfort and inconvenience. Bladder infections can be quickly and easily treated. And it's important to get treatment promptly to avoid the more serious infection that reaches the kidneys.

Sign And Sympotoms 
Urinary tract infections don't always cause signs and symptoms, but when they do they can include:

• A strong, persistent urge to urinate
• A burning sensation when urinating
• Passing frequent, small amounts of urine
• Urine that appears cloudy
• Urine that appears bright pink or cola colored — a sign of blood in the urine
• Strong-smelling urine
• Pelvic pain, in women
• Rectal pain, in men

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.

Kidneys (acute pyelonephritis)

• Upper back and side (flank) pain
• High fever
• Shaking and chills
• Nausea
• Vomiting

Bladder (cystitis)

• Pelvic pressure
• Lower abdomen discomfort
• Frequent, painful urination
• Blood in urine

Urethra (urethritis)
Burning with urination


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 grow 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 gastrointestinal bacteria spread 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, gonorrhea and chlamydia, also are possible causes of urethritis.

How is a UTI diagnosed?

To find out whether you have a UTI, your doctor will test a sample of urine for pus and bacteria. You will be asked to give a "clean catch" urine sample by washing the genital area and collecting a "midstream" sample of urine in a sterile container. This method of collecting urine helps prevent bacteria around the genital area from getting into the sample and confusing the test results. Usually, the sample is sent to a laboratory, although some doctors' offices are equipped to do the testing.
In the urinalysis test, the urine is examined for white and red blood cells and bacteria. Then the bacteria are grown in a culture and tested against different antibiotics to see which drug best destroys the bacteria. This last step is called a sensitivity test.
Some microbes, like Chlamydia and Mycoplasma, can be detected only with special bacterial cultures. A doctor suspects one of these infections when a person has symptoms of a UTI and pus in the urine, but a standard culture fails to grow any bacteria.
When an infection does not clear up with treatment and is traced to the same strain of bacteria, the doctor may order some tests to determine if your system is normal. One of these tests is an intravenous pyelogram, which gives x-ray images of the bladder, kidneys, and ureters. An opaque dye visible on x-ray film is injected into a vein, and a series of x-rays is taken. The film shows an outline of the urinary tract, revealing even small changes in the structure of the tract.
If you have recurrent infections, your doctor also may recommend an ultrasound exam, which gives pictures from the echo patterns of soundwaves bounced back from internal organs. Another useful test is cystoscopy. A cystoscope is an instrument made of a hollow tube with several lenses and a light source, which allows the doctor to see inside the bladder from the urethra.

How is UTI treated?

UTIs are treated with antibacterial drugs. The choice of drug and length of treatment depend on the patient's history and the urine tests that identify the offending bacteria. The sensitivity test is especially useful in helping the doctor select the most effective drug. The drugs most often used to treat routine, uncomplicated UTIs are trimethoprim (Trimpex), trimethoprim/sulfamethoxazole (Bactrim, Septra, Cotrim), amoxicillin (Amoxil, Trimox, Wymox), nitrofurantoin (Macrodantin, Furadantin), and ampicillin (Omnipen, Polycillin, Principen, Totacillin). A class of drugs called quinolones includes four drugs approved in recent years for treating UTI. These drugs include ofloxacin (Floxin), norfloxacin (Noroxin), ciprofloxacin (Cipro), and trovafloxin (Trovan).
Often, a UTI can be cured with 1 or 2 days of treatment if the infection is not complicated by an obstruction or other disorder. Still, many doctors ask their patients to take antibiotics for a week or two to ensure that the infection has been cured. Single-dose treatment is not recommended for some groups of patients, for example, those who have delayed treatment or have signs of a kidney infection, patients with diabetes or structural abnormalities, or men who have prostate infections. Longer treatment is also needed by patients with infections caused by Mycoplasma or Chlamydia, which are usually treated with tetracycline, trimethoprim/sulfamethoxazole (TMP/SMZ), or doxycycline. A followup urinalysis helps to confirm that the urinary tract is infection-free. It is important to take the full course of treatment because symptoms may disappear before the infection is fully cleared.
Severely ill patients with kidney infections may be hospitalized until they can take fluids and needed drugs on their own. Kidney infections generally require several weeks of antibiotic treatment. Researchers at the University of Washington found that 2-week therapy with TMP/SMZ was as effective as 6 weeks of treatment with the same drug in women with kidney infections that did not involve an obstruction or nervous system disorder. In such cases, kidney infections rarely lead to kidney damage or kidney failure unless they go untreated.
Various drugs are available to relieve the pain of a UTI. A heating pad may also help. Most doctors suggest that drinking plenty of water helps cleanse the urinary tract of bacteria. During treatment, it is best to avoid coffee, alcohol, and spicy foods. And one of the best things a smoker can do for his or her bladder is to quit smoking. Smoking is the major known cause of bladder cancer.

Prevention

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

• Drink plenty of liquids, especially water. Drinking water helps dilute your urine and ensures that you'll urinate more frequently — allowing bacteria to be flushed from your urinary tract before an infection can begin.
• 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 soon 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.

SOURCE:

National Institutes of Health, National Kidney and Urologic Diseases Information Clearinghouse