A method of combating rheumatoid arthritis, comprising administering to a human subject in need thereof, an effective oral dose of a probiotic composition in an oral dose form including, as the only bacterial species therein, the bacterial species of Bacillus subtilis, Bacillus coagulans, and Enterococcus faecium. The initial occurrence, and progress of remission of the rheumatoid arthritis condition incident to such probiotic therapy, may be established and monitored by assay of rheumatoid factor and/or anti-CCP antibodies present in a blood sample of the human subject.