Urinary tract infections are bacterial infections that occur in the kidneys, ureters, bladder or urethra. The infections are more common in women, especially women of reproductive age. According to the "Physicians' Desk Reference," a clinical reference manual, up to 35 percent of women have suffered from a urinary tract infection by the age of forty. The primary reason for the higher rate of infections in women is due to the way the female urinary tract is designed. The urethra, through which urine exits the body from the bladder, is shorter in women making it easier for bacteria to get to the bladder.
Biological Causes
Most cases of urinary tract infections are caused by bacteria. The Physicians' Desk Reference notes that 85 percent of infections are actually caused by a person's own vaginal or intestinal bacteria. Usually, the bacterial culprit is Escherichia coli, better known as E.coli, but occasionally other bacteria including Proteus, Klebsiella and Staphylococcus saprophyticus may be to blame. Urinary tract infections can also be caused by herpes simplex virus type 2 or other infections such as yeast infections. Although rare in the United States, parasites can also cause urinary tract infections. The bladder usually does an efficient job of getting rid of bacteria but when bacteria manage to linger around the urethra, or they travel from the anus or vagina to the urethra, they can cause infection.
Anatomical Causes
Problems associated with the flow of urine from the kidneys to the urethra can interfere with the removal of bacteria from the body and cause urinary tract infections. For example, if urine cannot be properly eliminated, this allows bacteria an opportunity to infect surrounding areas. Some women have an abnormal connection between the bladder and the vagina that can increase the probability of urinary tract infections.
Even temporary anatomical changes such as during pregnancy can increase the likelihood of developing an infection. One possibility for this is that pregnancy-related hormones change the shape of the urinary tract and interfere with urine flow.
Lifestyle Causes
Certain behaviors can inadvertently lead to urinary tract infections. For example, wiping from back to front spreads germs from the anus to the urethra, according to the U.S. Department of Health and Human Services. Other examples include having sex and waiting to go to the bathroom. Using a diaphragm, a birth control method that involves inserting a plastic "cup" into the vagina, can increase urinary tract infections. This risk is reduced by urinating before insertion and after having sex.
