Thanks for your reply sir.
I am using Streaming also on another server. Is it that inclusion of “username” in search like REST API v1.1 is not included in Streaming API ? Please confirm if scenario i mentioned above wont exist in Streaming API, if it is so then will then discard REST API because i am facing huge problem of username match in search 
Is there any way out except restricting few username like you mentioned
(-from:username1) because while searching we cant predict which username can match the query?