The sink, especially the faucet, can be wiped free of bacteria and food particles with an all-purpose cleaner. And we all should probably clean the faucet more often, considering it’s something we touch with raw-chicken-covered hands.
Sponges should be cleaned frequently, too, either by running them through the dishwasher or microwave. If you use a microwave, first make sure the sponge does not contain any metal, then get the sponge very wet and nuke it for two minutes; be careful when you remove it, as it will be quite hot.
Has your sponge holder developed mold or bacterial buildup? Use a toothbrush dipped in bleach or white vinegar — but never both, as the combination creates a dangerous chemical reaction — to scrub away mold. Follow by washing the sponge caddy with hot, soapy water or run it through the dishwasher.