Streptococcal viridans subacute bacterial endocarditis associated with antineutrophil cytoplasmic autoantibodies (ANCA)

We report an illustrative case of a 60-year-old man with Streptococcus viridans subacute bacterial endocarditis (SBE) and positive antineutrophil cytoplasmic autoantibodies (c-ANCA). C-ANCA positivity has been associated with a variety of rheumatic and infectious disease areas, but has been rarely associated with SBE. The patient had mitral valve prolapse with mitral regurgitation, and S viridans SBE developed after a dental procedure. Laboratory abnormalities included anemia, elevated erythrocyte sedimentation rate, positive rheumatoid factor, positive anticardiolipin antibody, positive lupus anticoagulant, and highly elevated c-ANCA level. We believe this is only the ninth reported case of S viridans SBE with a positive c-ANCA, and the third with mitral valve prolapse and vegetations.