Urinary tract infections

If you've had a urinary tract infection (UTI), you no doubt know the symptoms. Cystitis, or bladder infection, is generally heralded by the urge to urinate immediately, burning pain when you do, and the production of a surprisingly small amount of urine, which may be tinged with blood. Pyelonephritis -- infection of the ureters and kidneys -- is signaled by fever, nausea or vomiting, and frequently pain that may radiate from the small of your back through your groin and lower abdomen.

UTIs can occur throughout life, but the manifestations can be more diverse as we age. For example, elderly women in poor health may lose their appetites, may become lethargic or delirious, and may run high fevers, even when the infection is limited to the bladder.

How UTIs develop.
Over 80% of UTIs in younger women are caused by strains of E. coli, the relatively benign bacteria that normally colonize our intestinal tracts; post-menopausal women are more likely to be infected with several other microbes as well many of which are resistant to commonly used antibiotics. In 95% of cases, these bacteria are somehow transported from the rectum to the urethra. In rare instances, they enter the bladder via the blood. In the bladder, their growth is usually inhibited by mucus, or they are submerged in urine and flushed out. Many low-grade UTIs escape notice because the bacteria may be confined to the mucosal lining or their numbers may be too low to produce symptoms.

Certain practices can undermine the body's defenses against these bacteria. Failing to empty the bladder completely allows them to accumulate; sexual intercourse can carry them to the urethra; spermicide use may make the climate of the vagina more hospitable to them; and wearing a contraceptive diaphragm may affect urine flow.

The existence of other health conditions that affect the urinary tract or alter urine flow can also predispose women to UTIs. The infections are more frequent among women who are pregnant, as well as those who have neurological disorders, chronic disabling diseases, who are bedridden or who have indwelling catheters.

Heredity and anatomy can also play a role. Some women who have a certain blood antigen called P1 also have molecules on the cells lining the urinary tract that enable particularly virulent strains of E coli to adhere more readily. Because of this, they are unusually susceptible to cystitis. Conditions like vesicoureteral reflux, in which faulty valves at the junction of the bladder and ureters enable urine to back up into the kidneys, as well as obstructions like kidney stones or tumors, promote pyelonephritis. Atrophic urethritis, a thinning of the urethral lining that occurs in menopause, also makes women more vulnerable to UTIs.

Treating UTIs
If you are otherwise healthy and develop symptoms of a UTI, don't hesitate to call your health provider. He or she may want to get a urine sample for analysis and perhaps do a physical exam if your symptoms aren't clear cut.

Because high concentrations of antibiotics accumulate rapidly in the bladder, most cases of cystitis are treated with a 3-5 day course of antibiotics, usually a combination of trimethoprim and sulfamethoxazole. Drinking plenty of fluids can help to flush out bacteria. Avoiding irritants like coffee, alcohol, and spicy foods can alleviate discomfort.

Antibiotic treatment is successful in about 85% of cases. In the remainder, the infection may recur within a few days. If you have a recurrent problem your physician will almost certainly order a urine culture to identify the specific microbe causing the infection so that he or she can prescribe the most appropriate drug. For recurrent cases of cystitis and for all kidney infections, a longer course of antibiotics is necessary.

Some kidney infections are so dramatic that they warrant more aggressive measures. Occasionally, a particularly virulent or resistant case of pyelonephritis may require hospitalization and intravenous antibiotic treatment.

Prevention
If you have three or more UTIs a year, you should probably be taking measures to prevent them. There are some commonsense steps you can take, such as drinking several glasses of water a day, emptying your bladder after intercourse, and wiping from front to back after using the toilet. Although there are no controlled studies to support the practice, many women swear that drinking cranberry and citrus juices helps.

Some studies have indicated that it is possible to avert recurrence by taking a single dose of an antibiotic after sexual intercourse or a low dose every day. However, strains of bacteria that are resistant to a particular antibiotic tend to spring up when that drug is taken for a long time. A recent study indicated that a dally application of vaginal estrogen cream was more effective than antibiotics in preventing UTI in women over age 60 (see December 1993 HWHW).

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