Molecular characterization of a globally distributed lineage of serotype 12F Streptococcus pneumoniae causing invasive disease

These studies have identified a major genetic lineage of capsule serotype 1 2F Streptococcus pneumoniae, which has maintained two different types of th e pneumococcal surface protein A (PspA) virulence factor and caused invasiv e disease in geographically disjoint locations. Twenty outbreak strains fro m a Texas jail and Maryland day care center and 16 reference strains from T exas, Maryland, Washington, Michigan, Oklahoma, Missouri, Alaska, and Austr alia were examined. Although the Texas and Maryland outbreak strains were i ndistinguishable by IS1167 and boxA genotyping procedures, all strains exam ined were members of a genetically similar lineage. The microevolutionary h istory of pspA differed from that of the overall genetic background of the strains. Taken together, these findings suggested that the Texas and Maryla nd outbreaks were caused by different clones of a major genetic lineage of serotype 12F pneumococci, within which at least one PspA has been acquired via localized genetic recombination.