Recently, in Japan newly neonatal exanthematous disease was elucidated to be caused by staphyloccocal supcrantigcnic
exotoxins, mainly
TSST-1. We studied
exotoxins producibility of 43 strains of S. aureus isolated from neonates with exanthematous disease and examined antibody titers to
staphylococcal enterotoxin A, B, C (SEA, SEB, SEC) and
toxic shock syndrome toxin 1 (TSST-1) of the patients and control (umbilical cord blood from term infants). The results were as follows 1.34 of 43 strains (79%) isolated from the patients were SEC and
TSST-1 producing MRSA, 5 strains (12%) were SEB, SEC, and
TSST-1 producing MRSA, 1 strain (2%) was SEB and
TSST-1 producing MRSA, 2 strains (12%) were SEB producing MSSA and did not produce
TSST-1. The 1 strain (2%) was MSSA which produced SEC and
TSST-1. 2. 16 neonates with exanthematous disease, who showed typical clinical signs and laboratry findings of
thrombocytopenia, with SEC and
TSST-1 producing MRSA isolates had significantly low anti-TSST-1 antibody titers at onset (p < 0.05), compared with the control (umbilical cord blood from term infants):
TSST-1 appeared to the causative agent for the disease. In two neonates with exanthematous disease, with SEB- and non- TSST-1-producing MSSA isolates, anti-SEB antibody titers were low at onset, so SEB appeared to the causative agent for the disease. 3. In Japan, low anti-TSST-1 antibody titers were found in the umbilical blood samples from about 70% of term infants; and low anti-SEB or anti-SEC antibody titers were found in samples from only about 10% of them, that is, a number of term infants had anti-SEB and anti-SEC
antibodies. The majority of S. aureus isolated from neonates with exanthematous disease were
enterotoxin- and TSST-1-producing MRSAs. The results of our study by measuring
antitoxin antibody titers suggested that SEB and SEC might not be pathogenically responsible, but
TSST-1 was considered to be responsible for the majority of exanthematous disease. Prevalence of TSST-1-producing MRSA in the neonatal and premature baby ward is the main cause for the high incidence of this disease in Japan, whereas the low antibody titer to
TSST-1 in the mother, in comparison with the anti-
enterotoxin antibody titers, may also be a predisposing factor.