Urinary tract infections, or UTIs, are the second most common type of infection in the United States, according to the National Institute of Diabetes and Digestive and Kidney Diseases. Urinary tract infections occur 50 times more frequently in women than in men before age 50. After age 50, the incidence of UTIs in both men and women increases, but the number of men rises, decreasing the female to male ratio, the Merck Manual states. Many factors increase the risk of developing recurrent UTIs.
Incomplete Bladder Emptying
Incomplete bladder emptying increases the risk of recurrent UTIs. The rise in UTIs in men over age 50 occurs mainly because of the rise in prostate disease as men age. The prostate often enlarges, blocking urine flow and preventing the bladder from emptying completely during urination. Urinary tract infections occur more commonly when urine stagnates in the bladder, providing an opportunity for bacterial growth. Kidney stones also block the flow of urine and allow bacteria to grow in the bladder. People with congenital malformations that block urine flow also develop more frequent UTIs.
Decreased Resistance to Infection
Having diabetes increases the chance of having a UTI, because elevated glucose levels in the urine provide an increased chance for bacterial growth. People with immune disorders or who take medications to suppress the immune system are also more likely to have recurrent UTIs.
Urinary Catheter Use
A urinary catheter provides a direct passageway for bacteria to ascend through the urethra and into the bladder. People with indwelling catheters are especially prone to developing UTIs, but individuals who practice intermittent self-catheterization also are likely to have recurrent UTIs. People paralyzed below the waist may also have slow or incomplete bladder emptying due to decreased sensation.
Aging
As women age, estrogen levels drop. Changes in the tissue from lack of estrogen make recurrent UTIs more likely after menopause, according to MayoClinic.com. Fecal incontinence may also allow bacteria to travel from soiled garments up the urethra and into the bladder in older women.
Sexual Activity
Young women who are sexually active often develop more frequent or repeated UTIs, especially if they use a diaphragm and spermicide or spermicide-coated condom. Spermicide may allow growth of bacteria such as E. coli, a frequent cause of UTIs, the Merck Manual reports.
