D.N.
Add a cup of vinegar to the wash water. It wil lget out that smell. My son was a bd wtter and it did not matter how much soap I used or extra rinse. I also tried baking soda and borax but not the greatest, just lessened it. Once I saw the suggestin on here, I started and now use it for my towles and sheets as well since they can tend to sit in the closet for a few days before we actually use them. My daughter still has accidents sometimes and her stuff never smells. And a bottle of vinegar only costs $1.50 or so and lasts me at least a few weeks of laundry.