A good idea to stave off any potential infections from harboring bacteria in that moist environment is to soak those sponges and loofahs weekly in one part bleach to ten parts of water to sterile.
Keep them immersed for a few minutes before rinsing with water. Allow those sponges and loofahs to air dry thoroughly and hang them somewhere other than your moist, hot bathroom.
A few minutes devoted to giving those sponges and loofahs some tender loving care can only help keep your skin as beautiful as possible!