To clarify the relationship between the epidemics of severe
invasive group A streptococcal
infections (streptococcal Toxic Shock-Like Syndrome; TSLS) and common group
A
streptococcal infections in Japan, we examined the T serotypes of
S. pyogenes strains (group A
streptococci) isolated from clinical specimens of the streptococcal
infections (17999 cases) in
the period 1990–5, including the severe infections (TSLS)
(29 cases) in the period 1992–5.
Characteristic points of the analyses were: (1) dominant serotypes
of the infections in these
periods were T12, T4, T1, T28 and TB3264, which were consistently isolated;
(2) isolates of T3
rapidly increased through 1990 to 1994 while T6 decreased in the
period 1990–3; (3) when
Japanese area was divided into three parts, T3 serotype tended to spread
out from the north-eastern to the south-western area; (4) strains of T3
and T1 serotypes were dominant in the
TSLS. Dominant-serotype strains of streptococcal infections did not
always induce severe
infections and dominance of T3 serotype in the TSLS seemed to be
correlated with the increase
of T3 in streptococcal infections. These results may indicate that
certain clones of S. pyogenes are involved in the
pathogenesis of the TSLS.