Midtier to Midtier

I am an audit associate with 1.5 years experience and currently at a Midtier firm. I am unhappy with my current firm due to our office culture and politics and thinking of either switching to one of the other Midtier  firms in town or going into private. If I was to switch to the other Midtier firm, what is the best way to go about it without burning bridges at my current firm?