Systematic detection of mycoplasmas by culture and polymerase chain reaction (PCR) procedures in 209 synovial fluid samples.

The objective was to investigate the presence of mycoplasmas in rheumatoid arthritis (RA) and other chronic arthritides. Samples of synovial fluid (SF) were systematically collected from all patients presenting with an articular effusion. Each sample was divided into three parts. The first was kept for cytological count and culture on standard media for pyogens and mycobacteria, the second was cultivated on specific media for mycoplasmas and the third frozen for subsequent study by polymerase chain reaction (PCR). A total of 209 samples were studied. Half of the patients had inflammatory rheumatic diseases: RA (27), spondyloarthropathy (28), connective tissue disease (5), unclassified arthritis (45). The remaining suffered from other conditions, including osteoarthritis (60), gouty arthritis (19), haemarthrosis (5), post-traumatic effusion (2). Eight samples were positive by culture, two for Mycoplasma hominis; three for M. fermentans, one for M. salivarium, one for M. orale and one for Ureaplasma urealyticum. All the patients concerned had an inflammatory rheumatic disease: five had RA, one had psoriatic arthritis and two had unclassified arthritis. These results were confirmed by PCR in two cases (one M. fermentans, one U. urealyticum). The lack of sensitivity of the conventional PCR assay on SF is discussed. Mycoplasmas were mainly detected in SF of RA patients. These results raise the question of the possible role of mycoplasmas in the triggering and maintenance of inflammatory rheumatic diseases, especially RA.