the problem is that you can't wash/dry your symthetics hot enough to kill the bacteria or the fabric will melt. so you have to do something else to kill off the odor-causing bacteria.
try 1) soaking it with rubbing alcohol or Lysol
2) put it in a plastic bag so it doesn't stink up the freezer and freeze it for a week
3) after washing it, don't airdry it inside but line dry it in a sunny spot for a few days and see if the bright UV will help
4) microwave it and kill off the little bastard bacteria that way
5) if microwaves won't work, try an X ray machine, like at your dentist office.
6) go to hanford and nuke the fucker with some gamma rays!