Silestone microban as I mentioned in prior a post, rumours are not confirmed. Although Silestone microban publicity has disappeared from the market. The anti-bacteria was used heavily in marketing for the past few years, and if you check their current website .... you'll see that this was wiped out from existence.
Currently, the public doesn't know if they use it or not, truth is that the publicity did disappear. Why is a product called anti-bacteria?
Personally I was involved in a R&D project for anti-bacteria. And it was really simple to obtain, actually it's a chemical additive that is mixed in the proportion to the resin used in the material, so in truth the resin is anti-bacterial. I have put in a picture of a sample testing, basically you see the bacteria is avoiding the contact with the piece.
Anyway, the Italians have avoided using these types of additives, they continuously stated that quartz based material didn't contribute for bacterial action. The Spanish Silestone company used this for marketing, generalizing to all it's products, so everything produced by Silestone was anti-bacterial. I had clients discussing this as if it was a plus to buy Silestone, nevertheless today it's out ..