Using PCR for 16S rRNA, the presence of bacterial DNA in synovial tissue (ST) from a variety of inflammatory arthritides has been reported. To confirm this, we have applied the PCR with pan bacterial 23S rRNA and 16S rRNA primers, which both methods have been used successfully for bacterial identification in various clinical samples.
ST were collected at joint surgery from 81 patients: 42 rheumatoid arthritis (RA), 31 osteoarthritis (OA), 8 other inflammatory arthritides. Extremely strict precautions were followed in the clinics and laboratory to prevent contamination. Bacterial DNA could not been detected by PCR with pan 23S rRNA and 16S rRNA in any of the samples. The positive controls, including bacterial DNA and human DNA, were run with each sample, and were always positive. Further, using the same method, 5/15 (33%) synovial fluid samples from patients with Chlamydia reactive arthritis were PCR positive. The PCR sensitivity was 2-20 CFU/reaction determined by mixing the living bacteria with ST and using exactly the same experimental procedure as with the patient samples.
Gas chromatography-mass spectrometry has been applied to detect muramic acid (bacterial cell wall specific chemical component) in ST. Preliminary results suggest that low concentration of muramic acid can be detected in the ST from some patients with inflammatory arthritis.
Our results show that bacterial DNA in ST from RA and OA could not been detected by PCR for 23S rRNA and 16S rRNA. Instead, muramic acid could be detected by gas chromatography-mass spectrometry. These observations indicate that the presence of bacterial DNA in ST might not be as prevalent as previously suggested. Nevertheless, the bacterial components may exist in ST.