Had a look under the scope this evening at what was in the settled dregs at the bottom of a bottle. I can see plenty of regular yeast, but I can't see anything out of the ordinary. Certainly nothing that looks like (my notion of) Brett and no bacteria.
Does it taste/feel like 1.007?
I'd be looking at the person who has been looking after the barrel. Maybe doing the old butler's trick of syphoning off and replacing with water. A lot. ;)