Not only are these infections uncomfortable, they can cause kidney damage if not treated. It is important to understand the steps you can take to prevent infection, or recognize when to seek treatment if you develop a UTI.
The bladder is one organ of the urinary system. The rest of the system is made up of the kidneys, ureters and urethra (Figure 1). Urinary tract refers to the course that urine takes from the kidneys, down the ureters, into the bladder and out of the body through the urethra. This group of structures removes excess liquid and certain waste products such as urea from the body. It also maintains a balance of salts and other components in the blood.
The kidneys produce about 1.5 litres of urine every 24 hours. They help control blood pressure and produce a hormone that regulates red blood cell formation. The ureters are two narrow tubes eight to 10 inches long, that drain urine from the kidneys into the bladder. There are valves where each ureter enters the bladder to prevent the flow of urine back up into the kidneys.
The bladder can store about two cups of urine comfortably for two to five hours. Circular muscles in the bladder called sphincters prevent urine from leaking out of the bladder into the urethra.
Infection can occur all along the urinary tract. The three most common sites for urinary tract infections are:
Two-thirds of UTIs are limited to the bladder and urethra. Bacteria that are found in the bowel or feces are the usual cause of infections of the bladder and kidneys. These bacteria spread from the rectum or vagina, through the urethra, into the bladder and sometimes to the kidneys. The most common of the bacteria are Escherichia coli (E. coli) that normally live in the colon.
Kidney infections are less common than bladder infection but very mild kidney involvement is present in 30 per cent of women with symptoms suggesting urinary infection. They are often the result of a severe or untreated bladder infection. Kidney infection in very young children may cause permanent damage. In children, the elderly, or anyone with a weakened immune system, infection can spread from the kidneys into the blood stream (sepsis). This can be life-threatening.
Urethritis is usually caused by sexually transmitted infections such as gonorrhea or chlamydia and will not be discussed further here. A good Internet source of information on infections of the urethra and kidney can be found at drkoop. net/.
Women are 10 times more likely to get a urinary tract infection than men. Over 25 per cent of all adult women will have a bladder infection at some time. Twenty per cent of those will have recurrent infections. Eighty per cent of women who have had at least three bladder infections will have more. This may be because women who frequently get bladder infections have a difficult time clearing bacteria from their urinary tract.
Women have a short urethra, allowing easy movement of bacteria to the bladder from the area of the vagina or anus so bacteria will enter the urinary tract on occasion. Most women quickly clear these invaders from their urinary tract. Women who get infections cannot clear this bacteria as easily.
Sexual activity precipitates bladder infections in many women. The reasons for this are not entirely clear. It may be that sexual intercourse propels bacteria into the urethra. Women who use the diaphragm for birth control are at slightly increased risk of developing a UTI. Although pregnant women seem no more likely to get a UTI than non-pregnant women, infection may be more serious as it is more likely to travel to the kidneys.
UTIs are uncommon in men under age 50. They are usually due to an obstruction such as kidney stones (renal calculi) in younger men or an enlarged prostate gland in older men. An enlarged prostate can obstruct the flow of urine out of the bladder leading to increased risk of infection as well as making infection more difficult to treat. Some people are more prone to UTIs than others.
Abnormalities of the structures of the urinary tract occur quite frequently. The urinary tract is normally protected from infection by being repeatedly flushed with fresh (sterile) urine coming down from the kidneys. Any abnormality of the kidneys, ureters, bladder or urethra that slows the flow of urine can make it easier for infection to get started. Similarly, kidney stones can become lodged in the kidneys, ureters or bladder. The obstructed flow of urine can help infection to develop.
Anyone who is unconscious or not able to empty the bladder because of serious illness may need a piece of tubing (catheter) inserted into the bladder. When catheters must be left in place, the risk of infection is increased. UTIs are more common in people who have trouble fighting infection because of a weakened immune system. They are also more common in people with diabetes mellitus.
The occurrence of UTIs in the elderly is about 10 per cent. With aging, the percentage of men suffering from this infection increases. This is in part because older men can suffer from obstruction caused by an enlarged prostate, cancer of the prostate or narrowing of the urethra.
Severe UTIs become more common with advancing age. Along with an elderly person's reduced ability to fight infection, they are more likely to need catheters often because of illnesses requiring hospitalization or surgery. Repeated and more complicated infections also result from added factors such as a drop in the position of the bladder (prolapse), presence of small stones (calculi) or cancer anywhere along the urinary tract.
A urinary tract infection is accompanied by a range of symptoms. These include:
To learn if you have a bladder infection, your doctor will check your urine for the presence of pus, bacteria or special indicators of infection. You will be asked to provide a sample of urine by washing the genital area and collecting a mid-stream sample of urine in a sterile container. Usually the sample is sent to a laboratory for analysis.
The urine is examined for the presence of red and white blood cells and bacteria. The amount of red and white cells is an indication of the presence of infection. Sometimes your doctor may need to order special tests to determine which types of bacteria are present and the most effective antibiotic. If the laboratory cannot grow any bacteria, special tests may have to be carried out to detect such organisms as chlamydia or very unusual germs such as tuberculosis.
If your infection does not clear up with treatment, your doctor may suggest further tests. For instance, further investigation is often carried out after just one or two infections in men to rule out abnormalities. Ultrasound examination is a useful way to make sure the basic structure of the urinary tract is normal. Recurrent UTIs should be thoroughly investigated.
Sometimes a more detailed examination will include an intravenous pyelogram (IVP). An opaque dye is injected into a vein and a series of x-ray images of the urinary tract is taken. This can reveal fairly small changes in the structure of the tract.
Another useful test is cystoscopy. A cystoscope is an instrument made from a narrow tube containing several lenses, glass fibres (fibre optics) and a light source. With this instrument the specialist can see inside the urethra and bladder. Abnormal structures of the bladder and urethra that do not show up on other tests may be detected by cystoscopy.
There is no foolproof way to prevent UTIs. However, there are a number of steps women in particular can take to reduce their chances of getting an infection.
UTIs are treated with antibiotics. The medication your doctor will choose is determined by a number of factors including the history (e.g. recurrent infections, drug allergies), the bacteria identified in your urine and the tests done in the laboratory.
You may be advised to take the medication for anywhere from three to 14 days depending upon the circumstances. Several antibiotics work for most bladder infections. These are called 'first-line' drugs. If the bacteria are resistant or you are allergic to first-line drugs, then 'second-line' antibiotics would be used. Some common first and second-line antibiotics, and their trade names, are listed here.
In women with a first, uncomplicated bladder infection, a three-day course of one of the first-line drugs is effective 95 per cent of the time. However, there are several reasons why your doctor may suggest you take the medication longer.
If you are pregnant or your doctor determines the infection is in the kidney, your treatment will take longer, often 14 days. Your doctor may suggest your urine be checked after treatment to be sure all of the infection is gone.
Although you may feel better long before you have finished taking the antibiotic, you should take the full course as prescribed. If you stop the drugs too soon, some bacteria will still be present and the infection can flare up.
If you are pregnant, let your doctor know because some antibiotics should not be taken during pregnancy. Pregnant women should be treated for seven to 14 days, depending on the situation, and their urine should be checked to see if treatment has been successful.
Women who have had many bladder infections may benefit from the use of low doses of antibiotic. One approach is to take a single dose of an antibiotic after sexual intercourse. For frequent infections, some doctors prescribe daily, low dose antibiotic for up to six months.
Repeated bladder infections due to an underlying structural abnormality may need corrective surgery. Since UTIs in men are often related to some underlying problem, men with a first infection are treated more aggressively - usually for seven to 10 days. Also, men should always have a post treatment urinalysis to be sure the infection is entirely cleared up.
Older women discovered to have urinary infection on a routine urine test do not need treatment if they have no symptoms of infection. These infections without symptoms are common and persistent. Treatment is often more harmful than the infection.
See your doctor if you experience any of the following:
See your doctor as soon as possible if you:
Urinary tract infections can be troublesome and uncomfortable. When they are diagnosed quickly, treatment is usually simple and effective. If you think you may have a UTI, do not risk complications. See your family doctor.