As you age, your bladder loses elasticity and may not empty completely. Your estrogen level also drops. Research suggests that lower estrogen levels are associated with a decrease in the lactobacilli bacteria. Lactobacilli help maintain acidity in the vagina and control E. coli growth. It makes you more susceptible because your immune system is weakened.
Many women find that their UTIs recur before or after a particularly stressful event.
You must be examined by your doctor to rule out any of these problems.