Do you use a cup to hold all of your toothbrushes?  And have you noticed that after a while that yellowish, sticky gunk forms on the bottom of the cup?  I have a simple, quick and cheap solution to avoid that build up.  About once every two weeks before I shower, I check the cup to see if it is starting to build up and if it is, I take all the toothbrushes out, use a bathroom sized dixie cup filled with equal parts hot water and mouthwash and soak each toothbrush in its own cup to sterilize it.  While that is being done I fill up the cup that  I use to store all my toothbrushes about halfway with equal part hot water and mouthwash and let all of that sit while I shower.  Once I am done, I dump out the water and everything is clean - toothbrushes are sanitized which helps keep sickness from repeating and the gunk at the bottom of my toothbrush cup holder is gone.