Most urinary tract infections, or UTIs, are caused by bacteria that enter the urethra and then the bladder. A type of bacteria that normally lives in the bowel (called E. coli) causes most UTIs. UTIs can also be caused by fungus (another type of germ). Who Gets UTIs? Although everyone has some risk for UTIs, some people are more likely to get UTIs than others. These include people who have - spinal cord injuries or other nerve damage around the bladder.  - a blockage in the urinary tract that can trap urine in the bladder. The blockage can be caused by kidney stones, an enlarged prostate, or a birth defect.  - diabetes  - problems with the bodys natural defense (or immune) system  - pelvic organ prolapse, which is when pelvic organs (such as the bladder, rectum, or uterus) shift out of their normal position into the vagina. When pelvic organs are out of place, they can push on the bladder and urethra and make it hard to fully empty the bladder. This causes urine to stay in the bladder. When urine stays in the bladder too long, it makes an infection more likely spinal cord injuries or other nerve damage around the bladder. a blockage in the urinary tract that can trap urine in the bladder. The blockage can be caused by kidney stones, an enlarged prostate, or a birth defect. diabetes problems with the bodys natural defense (or immune) system pelvic organ prolapse, which is when pelvic organs (such as the bladder, rectum, or uterus) shift out of their normal position into the vagina. When pelvic organs are out of place, they can push on the bladder and urethra and make it hard to fully empty the bladder. This causes urine to stay in the bladder. When urine stays in the bladder too long, it makes an infection more likely UTIs in Women More than half of women will have at least one UTI in their lifetime. Women are more likely than men to get UTIs because they have a shorter urethra, making it easier for bacteria to reach the bladder. Also, the bowel and urethral openings are closer together in women than in men, making it easier for E. coli (a bacteria that lives in the bowel) to travel from the bowel to the urethra. Many women suffer from frequent UTIs. Some women have 3 or more UTIs a year. However, very few women will have frequent UTIs throughout their lives. More typically, a woman will have a period of 1 or 2 years with frequent UTIs. After this period, the UTIs may stop or happen less often. Older women are more likely to get UTIs because the bladder muscles weaken and make it hard to fully empty the bladder. This causes urine to stay in the bladder. When urine stays in the bladder too long, it makes an infection more likely. UTIs in Men Men are less likely than women to have a first UTI. But once a man has a UTI, he is likely to have another. Bacteria from a UTI can spread to the prostate. Once there, the bacteria can hide deep inside prostate tissue. Prostate infections are hard to cure because antibiotics may not be able to reach the infected prostate tissue. Activities That Can Increase Risk - Having sex. Sexual activity can move bacteria from the bowel or vaginal cavity to the urethral opening. Urinating after sex lowers the risk of infection.  - Using a catheter to urinate. A catheter is a tube placed in the urethra and bladder to help people empty the bladder. The catheter can make a direct path for bacteria to reach the bladder.  - Using certain birth controls. Diaphragms can bring bacteria with them when they are placed. Spermicides (a birth control that kills sperm) may also make UTIs more likely. Having sex. Sexual activity can move bacteria from the bowel or vaginal cavity to the urethral opening. Urinating after sex lowers the risk of infection. Using a catheter to urinate. A catheter is a tube placed in the urethra and bladder to help people empty the bladder. The catheter can make a direct path for bacteria to reach the bladder. Using certain birth controls. Diaphragms can bring bacteria with them when they are placed. Spermicides (a birth control that kills sperm) may also make UTIs more likely.