Detection of mycobacteria in joint samples from patients with arthritis using a genus-specific polymerase chain reaction and sequence analysis.

OBJECTIVE Mycobacteria have been implicated in the pathogenesis of various forms of arthritis. The aim of this study was to examine the diagnostic potential of molecular biological techniques as well as to investigate the pathogenetic role of mycobacteria in chronic arthritis. PATIENTS AND METHODS DNA, extracted from synovial fluid and synovial tissue samples from patients with mycobacterial septic arthritis (n = 2), seronegative spondyloarthropathies (SpA) (n = 18), undifferentiated arthritis (UA) (n = 21) and rheumatoid arthritis (RA) (n = 40), was analysed using a mycobacterial genus-specific polymerase chain reaction (PCR) applied to amplify mycobacterial DNA. Subsequently, automated sequencing was performed for speciation. Samples from patients with either non-mycobacterial septic arthritis, osteoarthritis (OA), crystal arthritis or joint trauma served as negative controls (n = 19). RESULTS Mycobacterium tuberculosis complex and Mycobacterium marinum were detected in the two patients with mycobacterial septic arthritis. The other species identified were Mycobacterium hodleri (in one RA patient), Mycobacterium smegmatis (in one OA patient and two RA patients) and Mycobacterium austroafricanum (in one crystal arthritis patient). All other samples were negative. CONCLUSIONS The results suggest that the mycobacterial genus-specific PCR applied on DNA extracts isolated directly from joint samples may be employed as an additional diagnostic tool in the case of clinical suspicion of a mycobacterial infection. No evidence was obtained for a pathogenetic role of mycobacteria in SpA, UA or RA.