Recognition and management of bacterial arthritis.

Bacterial arthritis is a bacterial infection of the joint. Apart from the classical gonococcal arthritis, nongonococcal arthritides include specific forms such as mycobacterial or Borrelia burgdorferi arthritis. Almost any bacterium can cause arthritis, provided that the route of penetration and the host response are suitable. Weakening of the host's immune competence, pre-existing joint damage and invasive diagnostic or therapeutic procedures are the main risk factors for bacterial arthritis. Gram-positive cocci are the species most frequently involved. The pathogenesis of bacterial damage includes release of toxins, cell production of cytokines and autoimmune reactions to specific antigens. The diagnosis can be suspected clinically put must be confirmed by culture of the synovial fluid, a test which can be complemented by scintigraphy. Amplification of bacterial DNA by polymerase chain reaction is a new procedure that could become an important tool for quick diagnosis. Treatment is based on joint drainage and antibiotics, which should be started as soon as the diagnosis is suspected. Corollary strategies under investigation include corticosteroids to prevent joint damage, monoclonal antibodies to arthritogenic peptides of bacteria or to surface markets of host lymphocytes, and modulators of synovial fluid cytokines.