Mo. Rev. Stat. § 356.181

Any privilege applicable to communications between a person rendering professional services and the person receiving such services recognized under the laws of this state, whether statutory or deriving from common law, shall remain inviolate and shall extend to a professional corporation or a foreign professional corporation, and its employees, in relation to professional services rendered to clients of the professional corporation or foreign professional corporation in all cases in which it shall be applicable to communications between a natural person rendering professional services on behalf of the professional corporation or foreign professional corporation and the person receiving such services.