Culture-negative severe septic shock: indications for streptococcal aetiology based on plasma antibodies and superantigenic activity.

We present a severe septic shock syndrome patient with negative blood cultures. Acute and convalescent plasma samples from the patient were analysed for anti-streptolysin O titres, superantigen-neutralizing activity and presence of superantigenic activity. The plasma analyses implicated superantigen-producing Streptococcus pyogenes as the causative agent.