Cystitis and Other Urfnary Tract Infections. Part 1. Etiology and Epidemiology

In the past few years, we have published essays on numerous health problems , includlng herpes simplex virus in-fections] and trichomoniasisz-sexually transmitted diseases that are especially serious for women. This two-part essay reviews a family of closely linked disorders that primarily affect women: uri-nary tract infections (UTIS). UTIS are among the most common infections encountered by physicians around the world. Although UTIS occur most often in elderly women, they are common in sexually active women as well. Indeed, it is estimated that 10 to 20 percent of all women everywhere will experience at least one episode of UTI.3 Most UTIS involve only the lower urinary tract.g This consists of the bladder , which stores urine, and the urethra, which carries urine from the body. Lower tract UTIS are designated by the terms cystitis (inflammation of the bladder) and urethritis (inflammation of the urethra—although some clinicians do not classify urethritis as a UTI). Indications of a lower-tract infection include: a frequent need to urinate, a burning sensation upon urination (dysuria), bacteria in the urine (bacteriuria), and occasional blood and pus in the urine (pyuria). Occasionally, however, disease-causing bacteria may travel beyond the ure-thra and bladder to invade the upper urinary tract. The upper tract consists of the kidneys and ureters. The kidneys filter wastes from the blood and concentrate them in the form of urine. The ure-ters are the fibrous, muscular tubes which carry urine from the kidneys to the bladder. An upper-tract infection, or pyelonephritis, is far more serious than its lower-tract counterpart. It generally combines the symptoms of lower-tract infections with fever, chills, nausea, vomiting, and pain in the lower back. And whereas lower-tract UTIS are virtually never life-threatening, pyelone-phritis can cause massive kidney damage in a small percentage of cases. In rare instances , chronic pyelonephntis can lead to a systemic blood infection, which can cause death. One goal of lower-tract treatment is to prevent the spread of the disease to the upper urinary tract—not the mere relief of symptoms.d.s In the past, lower-tract infections were thought to have a single cause, treatable with a few types of therapy.b Now, however, many causes have been identified. ThN has in turn resulted in an increase in the types of therapy available , and in controversies over the best treatment. The causes of lower-tract UTIS are discussed here. Diagnosis and treatment will be covered later. Brook, the most common bacteria …