Enterobacteria, in particular Klebsiella spp., have been implicated in
the aetiopathogenesis of ankylosing spondylitis. A comprehensive exam
ination of the faecal flora of 82 patients with ankylosing spondylitis
, either primary (67), or in association with inflammatory bowel disea
se (4), reactive arthritis (6) or psoriatic arthritis (5), was perform
ed and compared with that of a control population (36) of healthy indi
viduals. The range of flora identified was similar in both populations
and there was no increased isolation rate of Klebsiella or other prop
osed arthritogenic organism in those with spondyloarthropathy. In thos
e patients in whom Klebsiella was identified, its presence was not rel
ated to disease activity, the erythrocyte sedimentation rate or C-reac
tive protein.