In reactive and
postinfectious arthritis the joints are generally sterile but the presence of
bacterial antigens and
nucleic acids has been reported. To investigate whether organisms traffic to affected joints in these conditions, we performed reverse transcription PCR using universal primers to amplify any bacterial
16S rRNA sequences present in synovial fluid. Bacterial sequences were detected in most cases, even
after treatment of the synovial fluid with
DNase, implying the presence of
bacterial RNA and therefore of transcriptionally active bacteria. Analysis of a large number of sequences revealed that, as reported in
rheumatoid arthritis, most were derived from gut and skin commensals. Organisms known to have triggered
arthritis in each case were not found by sequencing the products obtained using universal primers, but could in some cases be shown to be present by amplifying with species specific primers. This was the case for Yersinia pseudotuberculosis and Chlamydia trachomatis. However, in
arthritis thought to be related to
Campylobacter infection the sequences obtained were not from Campylobacter jejuni or C. coli, but from other Campylobacter spp. that are not known to be associated with
reactive arthritis and are probably present as commensals in the gut. We conclude that although rRNA from
reactive arthritis associated organisms can be detected in affected joints,
bacterial RNA from many other bacteria is also present, as was previously noted in studies of other forms of inflammatory
arthropathy.