>Keep in mind of course that male urine is generally
>more sterile than female urine because men have much
>longer urethras--which is why women are more prone to
>UTI's then men....
The female urethra is much shorter than the male's, and the opening of the urethra is closer to the anus in a woman. Bacteria from both the anus and the vagina can enter the female urethra very easily, which may account for the much higher rate of urinary tract infections in women.
Unless there is an infection in the kidney itself, urine produced by the kidneys is sterile. Urine however, is both warm and moist, making it a perfect breeding ground for bacteria that may have found their way into the bladder or urethra. In most cases, the act of urinating flushes the bladder and urethra clean of bacteria, but infections can still occur, especially if there are large amounts of bacteria or the bladder fails to empty completely.
http://www.urinary-tract-infections.com/