Increased expression of the ska gene in emm49-genotyped Streptococcus pyogenes strains isolated from patients with severe invasive streptococcal infections.

Since 2000, emm49-genotyped Streptococcus pyogenes strains have been isolated from patients with severe invasive group A streptococcal infections in Japan, although they had not been isolated before 1999. We compare the characteristics of these strains with those of strains isolated from patients with non-invasive infections. SmaI-digested pulsed-field gel electrophoresis profiles of the isolates were almost indistinguishable between these groups, however, we found that ska (streptokinase gene) transcriptional levels in the strains isolated from patients with severe invasive infections were significantly higher than those in non-invasive infections.