Identification of an Insertion Sequence Located in a Region Encoding Virulence Factors of Streptococcus pyogenes

An insertion sequence, IS1562, was identified in a Streptococcus pyogenes strain of the clinically important M1 serotype. IS1562 is located in the mga regulon between the genes coding for the M protein and the C5a peptidase, both important virulence factors. The same or similar insertion sequences were found in most S. pyogenes strains, but the chromosomal location differed among isolates.