GLOMERULONEPHRITIS ASSOCIATED WITH MRSA INFECTION - A POSSIBLE ROLE OF BACTERIAL SUPERANTIGEN

We report 10 cases of glomerulonephritis following methicillin-resista nt Staphylococcus aureus (MRSA) infection. The clinical features of th is syndrome were an abrupt or insidious onset of rapidly progressive g lomerulonephritis (RPGN) with nephrotic syndrome and occasionally purp ura, following MRSA infection. The renal histologic findings showed a variety of types of proliferative glomerulonephritis with varying degr ees of crescent formation; immunofluorescence revealed of glomerular d eposition of IgA, IgG, and C3. Laboratory findings showed polyclonal i ncreases of serum IgA and IgG, with high levels of circulating immune complexes (ICs). Increased numbers of DR(+)CD4(+), and DR(+)CD8(+) T c ells were observed in the peripheral circulation, with a high frequenc y of T cell receptor (TCR) V-beta(+) cells. MRSA produced enterotoxins C and A and toxic shock syndrome toxin (TSST)-1, all of which are kno wn to act as superantigens. From the above observations, we speculate that post-MRSA glomerulonephritis may be induced by superantigens caus ing production of high levels of cytokines, and polyclonal activation of IgG and IgA. The formation of ICs containing IgA and IgG in the cir culation result in development of glomerulonephritis and vasculitis. A ccordingly, microbial superantigens may play an important role in the pathogenesis of this unique syndrome of nephritis and vasculitis.