In alternative embodiments, the invention provides compositions and methods for treating, ameliorating and preventing various disorders and conditions in mammals, including genetically-predisposed and chronic disorders, where the microbial or bacterial flora of the bowel is at least one causative or symptom-producing factor, for example, where the microbial or bacterial flora of the bowel manufactures neurotoxins or neurotoxic agents that enter the body through the gastrointestinal (Gl) tract, e.g. the colon, and reach the systemic space, e.g., by neural streaming or via the circulation, to reach the central nervous system (CNS), including the brain, the peripheral nervous system (PNS), and other nervous systems. In alternative embodiments, methods and compositions of the invention comprise or comprise use of medications, formulations and pharmaceuticals comprising rifaximin or equivalent active agents that can suppress or eradicate the microbiota super-infection that causes various psychotropic disorders. These compositions have been found to be affective in a broad spectrum of disorders but particularly in the obsessive compulsive disorder group (OCD).
