This is mostly due to anatomy and the fact that the female urethra is much shorter than the male urethra. Bacteria from around the anal area can more easily work their way up into the female bladder leading to infection. There are other causes as well, but they are much less common. Your mom is post-menopausal and therefore, she is estrogen deficient. Studies are inconclusive as to whether or not estrogen treatment can reduce the frequency of urinary tract infections.
Proper hygiene is obviously important including always wiping front to back.
Oral estrogen should be considered in your mom's case due to its beneficial effect on osteoporosis. Heather Orey Copyright 1998-2001 CME, Inc.