Mycoplasmas and 'diphtheroids' in rheumatoid arthritis.

The failure to isolate conventional mycoplasmas from 88 synovial membranes and 119 synovial fluids from patients with proven rheumatoid arthritis using a variety of culture media and techniques agrees with the results of recent workers and suggests that these organisms are unlikely to play a role in the aetiology of the disease. In contrast, 'diphtheroid' organisms were isolated from 27 to 30% of rheumatoid specimens, but not from cultures of non-rheumatoid material. A significantly higher incidence of raised agglutination titres to C. acnes and to a 'diptheroid' isolated from a patient with rheumatoid arthritis in sera from patients with rheumatoid arthritis supports the conclusion that these organisms are present in the joints in such patients, though their role in this disease has yet to be established.