Acquisition of Insertion Sequences and the GBSi1 Intron by Streptococcus agalactiae Isolates Correlates with the Evolution of the Species

Abstract
The prevalence of insertion sequences IS 1548 , IS 861 , IS 1381 , and ISSa4 and of the group II intron GBSi1 within Streptococcus agalactiae human isolates strongly correlates with the genetic lineages obtained by multilocus sequence typing. Our results yielded an evolutionary scheme for the acquisition of these genetic elements linked to the ecosystems from which the isolates were obtained.