I looked at the county website... couldn't find that option.
I can't find it either at the county level. Found a reference to a statewide fictitious business name database through Hong Kong University. I'll try to track that down.
I can't seem to get into the county property tax records - can you? Might check deeds and liens too.
In PA, fictious business names are not registered in the county, but with the State Dept.