Do NOT want to get nested group results in active directory search

Question

I am trying to interogate active directory and add the contents in a dropdown list. I have been succesfull so far, but my only issue is I am getting the nested groups from my search base and filter below and I do not want this to happen. How do I NOT get nested groups results from my code below?

var searchFilter = "(&(objectClass=group))";
var searchBase = "ou=Apps,ou=Applications,ou=Groups,dc=xx,dc=xx,dc=xx";

Many thanks, George