Increased expression of ska gene in emm49-genotyped strains of Streptococcus pyogenes isolated from patients of severe invasive group A streptococcus infections

Since 2000, emm49-genotyped Streptococcus pyogenes strains have been isolated from patients of severe invasive GAS infections in Japan, but not isolated before 1999. In all cases, renal impairment was caused in the early stage. We thought that this renal impairment in the early stage was due to the increase of streptokinase (ska) expression. In the present study, we compared ska transcriptional level between emm49-genotyped strains from severe invasive and non-severe invasive streptococcal infections. We showed that the ska transcriptional levels in the strains isolated from patients of severe invasive infections were higher than those of non-severe invasive infections, and this enhancement of the transcription was not caused by Fas activator and sagA/pel mRNA that activate ska expression.