TNF and rheumatoid arthritis: For RA patients on prednisone, 4 out of 16 (25.0%) of RA patients were positive for MAPbacteremia, while 6 out of 23 (26.1%) RA patients on anti-TNF-α medications (Humira®, Enbrel®, Simponi®, and Cimzia®) also were positive for MAPbacteremia.