Within Actinobacteria some researchers use the glutamine synthetase gene. For a reference please see this:

http://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-9-48

More recently, other phylogenetic markers have been suggested specifically for actinomycetes:

http://rsob.royalsocietypublishing.org/content/3/10/130073

http://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-9-48

Using Vitek-2 or bioMerieux can be done upon isolation in selective actinomycetes agar.

Thank you,... @Aparna... Can you give any reference paper?

Another possibility are  gyrB-rpoB-recA-relA and atpD  publicated in:

Multilocus sequence analysis of the actinobacterial genus Kribbella.

http://www.sciencedirect.com/science/article/pii/S0723202012001063

However SsgA, SsgB, FtsZ cited above are very specific and good choices... 

Thank you all..

I will check it