"After each teeth brushing, I rinse and wipe the shank of the brush to remove most particulates, then spray the shank and bristles generously, after which I top the brush head with the plastic provided (Sonicare) cap."
In the book Kiss Your Dentist Goodbye the good dentist advises to never store your toothbrush in a container, as the most important thing is to thoroughly dry it before using it again. A cap could re-infect and lengthens drying. She advises to have two or three toothbrushes and rotate them. One for morning, one for evening, and a third if you brush midday for this reason. I've heard her say it would be good to throw some Listerine on your toothbrush after you brush... but most important is thorough drying.
She also advises against having them in the bathroom.
She doesn't talk at all about getting new ones every 3 months...
FWIW