Detection of oral bacterial DNA in synovial fluid

Objectives As periodontal bacteria might be involved in the aetiology of rheumatic diseases, we analysed synovial fluid obtained from patients with rheumatoid arthritis (RA) and controls for the presence of DNA of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, and Treponema denticola. Methods In all, 42 patients suffering from RA (mean age 53.8 ± 16.7 years, 40.4% females) and 114 controls with no rheumatic diseases (mean age 56.1 ± 15.2 years, 52.4% females) were included. DNA from synovial fluid was isolated by QiaAmp kit (Qiagen, Hilden, Germany). Polymerase chain reactions (PCRs) specific for the 16S rRNA genes of the above specified bacteria were developed. Subgingival bacterial colonization was analysed using micro‐Ident® test (HAIN‐Diagnostik, Nehren, Germany). Results In patients with RA DNA of P. gingivalis was detected in synovial fluid more often than in controls (15.7% versus 3.5%, p = 0.045). More patients than controls harboured DNA from P. gingivalis in both, oral plaque and synovial fluid (11.9% versus. 0.9%, p = 0.030). Among the patients group the number of missing teeth was correlated with the number of joints with movement restrictions caused by RA. Conclusions DNA of periodontopathogens can be found in synovial fluid and oral bacteria may play a role in the pathogenesis of arthritis.