Antibodies to Klebsiella and Proteus microorganisms in ankylosing spondylitis and rheumatoid arthritis patients measured by ELISA.

Antibodies to Klebsiella oxytoca and Proteus mirabilis in 21 active ankylosing spondylitis (AS), 13 active rheumatoid arthritis (RA), 19 inactive RA patients and 18 healthy controls were measured using enzyme-linked immunosorbent assay (ELISA). Elevated anti-Klebsiella antibodies were demonstrated in active AS patients compared to active RA (p less than 0.01), inactive RA patients (p less than 0.001) and controls (p less than 0.005). When measuring antibodies to Proteus, active RA patients showed higher levels of antibodies compared to active AS patients (p less than 0.005) and healthy controls (p less than 0.05). Further investigations are required to assess the role of Klebsiella and Proteus microorganisms in AS and RA respectively.