Antibodies against superantigenic exotoxins produced by Staphylococcus aureus in sera from mothers and their infants' cord blood

Abstract

A novel neonatal disease and puerperal toxic shock syndrome (TSS) induced by a superantigen, TSS toxin-1 (TSST-1), has spread throughout Japan. It is important to investigate serum titers against exotoxins in new mothers and in their infants' cord blood. We investigated antitoxin antibodies against TSST-1, staphylococcal enterotoxin (SE) A (SEA), SEB, and SEC, including immunoglobulin G (IgG) subclass specificity by enzyme-linked immunosorbent assay, in sera from 221 mothers and 97 cord blood samples. The rate of mothers with negative anti-TSST-1 antibody titer was high (more than 40%). Although antitoxin antibody titers in the sera of cord blood were well correlated with those in the sera of the mothers for every toxin, the tendencies of antibody transmission differed between toxins. Anti-TSST-1 antibody consisted mainly of IgG1 and IgG4 subclasses. Anti-TSST-1 IgG1- and IgG4-specific antibody titers in cord blood were well correlated with those in the sera of the mothers. The low frequency of pregnant women with positive anti-TSST-1 antibody titers could be one reason for the spread of TSS in Japan. Neonates whose mothers have positive IgG titers against TSST-1 should be protected because the antibody is composed of the subclasses transferred well through the placenta.