Staphylococcus aureus isolated from Kawasaki disease patients hyper-releases extracellular protein A

S. aureus isolates from patients with Kawasaki disease (KD) release high levels of extracellular protein A (SpA), as compared to S. aureus in other diseases. The molecular weight of this released protein A is about 70 kDa. Extracellular KD SpA purified by affinity chromatography possessed the same amino acid sequence at the NH2-terminal IgG binding region and the same antigenic specificity as recombinant and cell-wall-bound SpA preparations. The size of DNA fragments containing the spa gene from S. aureus KD strains was 160-165 kb. All of these DNA fragments contained the igb portion encoding the IgG-binding region of KD SpA. Significantly higher molecular size of the SpA molecules hyper-released in the stationary-phase culture and the lack of production of other exo-proteins allow us to speculate that S. aureus isolated from patients with KD have mutations occurring in the agr locus.