Steam cleaning is a good way to kill bacteria and other microbes that might be living in your mattress. For the best results, first vacuum your mattress to remove surface debris and dust, and treat any stains with a fabric-safe cleanser or stain remover. If you like, you can also put your mattress out in the sun for a few hours to air it out. After steaming your mattress, spray it lightly with an anti-microbial spray. Don’t soak it—spray on a light layer and wipe it dry when you’re done.