We were told to wipe ourselves from front to back after using the bathroom. This is because the urethra, the tube that carries urine from the bladder to the outside of the body, is located near the anus. Bacteria from the large intestine, such as E.coli, are in the perfect position to escape the anus and invade the urethra. From there they can reach the bladder and, if the infection is not treated, continue to infect the kidneys. Women may be particularly prone to urinary tract infections because they have a shorter urethra, which allows bacteria quick access to the bladder. Having sex can also introduce bacteria into the urinary tract