Identification of Mycoplasma fermentans in synovial fluid samples from arthritis patients with inflammatory disease

Since 1970 Mycoplasma fermentans has been suspected of being associated wit h rheumatoid arthritis. However, this association has been difficult to pro ve, and this has been our goal. The distribution of M.fermentans was studie d in the synovial fluid of patients suffering from different arthritides. S amples of synovial fluid were taken from patients with well-defined disease and a clear diagnosis. After removal of the inflammatory cells and hyalura n, they are treated with proteinase K and tested by a single or fully neste d PCR with primers directed against part of the two 16S rRNA genes of M. fe rmentans. The product was sequenced automatically, by using an ALF Express automatic sequencer, to confirm the mycoplasma species and to identify the strain since the two genes were usually found to be polymorphic. This was a lso true of the type strain, strain PG18, M.. fermentans was detected in 23 of 26 (88%) rheumatoid arthritis patients, and four different strains were found. It was also found in 7 of 8 (88%) of the nonrheumatoid inflammatory arthritis patient group, which consisted of one patient with reactive arth ritis, one patient with pauciarticular juvenile chronic arthritis, two pati ents with gout, two patients with ankylosing spondylitis, and two patients with psoriatic arthritis, only one of whom was infected with M. fermentans. It was not detected in any of the 10 osteoarthritis patients. M. fermentan s was therefore found to be a variable and very common organism in arthriti c patients with inflammatory joint exudates and may well prove to be import ant in the etiology of the diseases.