Bacteria are considered to be important in the pathogenesis of several forms of arthritis. The goal of this study was to apply the 16S ribosomal RNA (rRNA)-polymerase chain reaction method for the detection of bacterial DNA in synovial fluid (SF) and synovial tissue (ST) from inflamed joints.
Samples from 5 patients with septic arthritis and from 7 with osteoarthritis or arthritis secondary to joint trauma were used as controls. Samples from 6 patients with spondylarthropathy (SpA) and from 20 with undifferentiated arthritis (UA) were analyzed for the presence of bacterial DNA using universal 16S rRNA primers. Automated sequencing and comparative data analysis were performed to identify the species.
In the positive control group, the bacterial species cultured from the synovium could be identified in all cases. No bacterial DNA was detected in the SF and ST from patients in the negative control group. In 4 of 6 patients with SpA and 7 of 20 with UA, the analysis of joint samples revealed the presence of bacterial DNA. Sequence analysis indicated the presence of multiple species, which was confirmed by sequencing of cloned products.
When the the above techniques were used with a stringent regimen, we were able to demonstrate that it is possible to collect and analyze joint samples without contaminating bacterial DNA. The accumulation of phagocytic cells that contain bacterial DNA of various species could play a role in the pathogenesis of both SpA and UA.