[Laboratory diagnosis of rheumatic diseases. Part 3: arthritides caused by infection].

This third part of this series of articles on laboratory diagnostics of rheumatic diseases considers the rheumatic diseases caused by infection by microorganisms, or reactive arthritides. The basis for laboratory diagnostics of infection-reactive arthritides is the investigation of anti-infection antibodies. In some situations, DNA amplification methods may be helpful. Bacterially infected joints should be immediately examined by arthrocentesis and microscopic examination and laboratory culture of the synovial fluid.