IS UNDIFFERENTIATED SERONEGATIVE SPONDYLOARTHROPATHY A FORME-FRUSTE OF REACTIVE ARTHRITIS

Undifferentiated spondyloarthropathy (USpa) may either represent a for me fruste of other spondyloarthropathies like reactive arthritis or be a different disease entity. To study the link between USpa and reacti ve arthritis, we studied the presence of IgA antibodies to Yersinia en terocolitica, Salmonella typhimurium, Shigella flexneri, Campylobacter jejuni and Chlamydia trachomatis in sera from 14 patients with USpa ( European Spondyloarthropathy Study Group criteria) using ELISA. Escher ichia coli was used as a central antigen. An OD value of more than the mean + 2 S.D. of 51 blood donors was considered positive. Five patien ts had elevated IgA antibodies to S. flexneri, while two patients each had elevated antibody levels to S. typhimurium and Chlamydia. No pati ent had elevated antibodies to Y. enterocolitica, C.jejuni and E. coli . Among 51 normals, 1, 4, 3, 2 and 3 had elevated antibodies to S. fle xneri, S. typhimurium, Y. enterocolitica, C. jejuni and E. coli, respe ctively. Nine of 14 patients with USpa had antibodies to one of the ba cteria implicated in reactive arthritis; of these, antibodies to Shige lla were the most frequent. Thus, a proportion of patients with USpa m ay in fact have reactive arthritis.