ABSTRACT
The distribution of intermedilysin, a human-specific cytolysin, among the anginosus group streptococci and the correlation of toxin production and infection by
Streptococcus intermedius
were investigated. PCR and Southern hybridization specific for the intermedilysin gene revealed that the toxin gene exists only in
S. intermedius
and no homologue to the toxin gene is distributed in
S. anginosus
and
S. constellatus
. Thus, the intermedilysin gene is useful as a marker gene of
S. intermedius
. Moreover, a human-specific hemolysis assay and Western blotting with intermedilysin-specific antibodies clearly demonstrated that the intermedilysin production level in isolates from deep-seated infections, such as brain and liver abscesses, is higher (6.2- to 10.2-fold, respectively) than in strains from normal habitats, such as dental plaque, or from peripheral infection sites. However, other candidate virulence factors of
S. intermedius
, such as chondroitin sulfate depolymerase, hyaluronidase, and sialidase activities, did not show such a clear correlation between enzymatic activity and isolation sites or disease severity. From these results, intermedilysin is likely to be the pathogenic or triggering factor of significance in inducing deep-seated infections with
S. intermedius
.
Effect on Polymorphonuclear Cell Function of a Human-Specific Cytotoxin, Intermedilysin, Expressed by Streptococcus intermedius
