A urinary tract infection, abbreviated as UTI, is caused by bacteria that colonize the urinary tract. UTIs can develop anywhere in the urinary tract, including the kidneys, bladder or urethra, which is the tube that urine passes through as it leaves the body. Recurrence of urinary tract infections is common: Approximately 25 to 50 percent of women develop a second UTI within six months of the first UTI, according to FloridaHealthFinder.gov. Although some risks factors are known, doctors still do not fully understand all the causes of frequent UTIs.
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Obstructions of the Urinary Tract
Urine helps to keep the urinary tract free of infection by washing away bacteria. Any factor that reduces or obstructs the flow of urine can cause frequent UTIs. Kidney stones are one common cause of frequent UTI, because they can disrupt urine flow through the urinary tract. In men, an enlarged prostate gland can obstruct urine flow and increase the risk of UTI, the National Kidney and Urologic Diseaes Information Clearinghouse reports. Some people are born with abnormalities of the urinary tract, which can hinder normal urination and cause UTIs.
UTIs occur more frequent in women than in men. Doctors suspect that one reason for frequent UTI in women is that women have a much shorter urethra than men, which means bacteria can more easily migrate into the bladder, explains the Mayo Clinic. In addition, in women, the urethra is closer to the anus, which makes it more likely that bacteria from the anus will infect the urethra. After menopause, women often develop more frequent UTIs, because the changes in estrogen levels make the urinary tract more susceptible to infection.
Sexual activity in women seems to trigger frequent UTI, for a reason doctors still do not fully understand, reports Medline Plus. In addition, several studies have linked the use of diaphragm for birth control with an increased risk of UTI. The use of spermicidal lubricants for birth control have also been shown to increase the frequency of UTIs.
Any disease that impairs the immune system increases the risk for UTIs, because the body is not able to fight the infection. For example, people with diabetes are more likely to develop a UTI, according to the University of California Los Angeles Health System. In addition, some conditions render people unable to urinate normally, requiring a catheter to be inserted into the urethra. The catheter often introduces bacteria into the urethra, causing infections.