I dont use any herbals personally, and have only limited knowledge about brucella. I know in veterinary medicine it is often treated with rifampin combined with doxy for a long period of time (4-6 months or more) There is some research that says doxy plus streptomycin is used effectively in people, but streptomycin requires daily IM injection.
But back to your original question, here's what "Mr. Herbs" himself, Buhner has to say about treating brucella with herbals:
" I would recommend that you use a mixture of Lomatium dissectum and Ligusticum porterii (osha) – along with Sida and Isatis, to treat it. It will respond to some extent to those first two plants. It is also susceptible to juniper berry, I would try 10 drops of that 3x daily for 10 days and see if it helps. The first mix can be used 30 drops 3-6x daily for a few months."
Again I have no experience using herbs for any infection, so to me the above paragraph sounds like a foreign language, but perhaps it makes sense to you.
goshawk gave some good warnings about
the potency of some of the herbs. Be aware that lomatium can cause hives/rash. If you get it, stop the lomatium. I ordered a bottle to keep on hand as it is a valuable herb. Not sure when I'll brave trying it out, though.