Objective: Bacteria play a crucial pathogenetic role in Lyme arthritis (LA), reactive arthritis (ReA), other forms of spondyloarthropathy (SpA), and possibly in undifferentiated oligoarthritis (uOligo). Polymerase chain reaction (PCR) technology has been applied to detect bacterial DNA of individual microbes in synovial fluid (SF) of patients with arthritides. We screened for DNA sequences of 8 bacterial species simultaneously in SF of patients with inflammatory joint disease.
Methods: We examined 104 SF samples of 96 patients with ReA (n = 13), undifferentiated SpA (uSpA, n = 10), uOligo (n = 50), juvenile chronic arthritis (JCA, n = 13), and rheumatoid arthritis (RA, n = 10). A nested PCR approach was developed to detect DNA sequences of 8 bacteria: Chlamydia trachomatis, C. pneumoniae, Yersinia enterocolitica, Salmonella enteritidis, Campylobacter jejuni, Shigella flexneri, Klebsiella pneumoniae, and Borrelia burgdorferi. The detection limit was determined at 10 bacterial/sample. Serology and lymphocyte proliferation assay were done in parallel in most patients.
Results: In 12 cases bacterial DNA of B. burgdorferi (n = 7), C. trachomatis (n = 2), C. jejuni (n = 2), and C. pneumoniae (n = 1) was detected in patients with uOligo (n = 9) and JCA (n = 3), while no evidence of bacterial DNA was found in patients with ReA, uSpA, and RA. Shigella flexneri DNA was detected in 4 cases, but the significance of this finding remains uncertain due to the high sequence homology of this species with Escherichia coli. DNA of Y. enterocolitica, S. enteritidis, or K. pneumoniae was not found. A positive serologic response was found in 7/9 PCR positive patients. In 11/96 cases antibodies to 2 or more bacteria were found in parallel (11.5%). Antigen specific lymphocyte proliferation was observed in 5/9 PCR positive patients.
Conclusion: Bacterial DNA was detected in peripheral joint of patients with uOligo and JCA, but not in ReA, uSpA, or RA in this study. The detection of bacterial DNA in synovial material by PCR technology gives useful diagnostic information, especially when antibodies against several microbes are present or antibodies are not detectable. Failure to detect bacterial DNA in patients with ReA and uSpA with longstanding disease suggests that in later stages autoimmune mechanisms may operate.