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 diagnosti
c or therapeutic procedures are the main risk factors for bacterial ar
thritis. 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 but must be confirmed by c
ulture of the synovial fluid, a test which can be complemented by scin
tigraphy. Amplification of bacterial DNA by polymerase chain reaction
is a new procedure that could become an important tool for quick diagn
osis. Treatment is based on joint drainage and antibiotics, which shou
ld be started as soon as the diagnosis is suspected. Corollary strateg
ies under investigation include corticosteroids to prevent joint damag
e, monoclonal antibodies to arthritogenic peptides of bacteria or to s
urface markers of host lymphocytes, and modulators of synovial fluid c
ytokines.