Comparative eBURST diagram showing changes between the 2009 and 2011S. pneumoniaecarriage isolates in children 3 months - 7 years from Massachusetts communities. Each ST is represented by a point, the size of which is determined by the number of isolates with that ST in the combined dataset. STs differing at a single MLST locus are shown linked by a straight line. A clonal complex (CC) is a group of STs sharing 6 of 7 alleles with at least one other member of the group. STs which are the putative founders of their CC are shown in blue, with those which are thought to have given rise to subgroups shown in yellow. Those STs which cannot be linked to any other in the sample are termed singletons and appear as unlinked points. For more information see http://spneumoniae.mlst.net/eburst/. The ST numbers are colored according to whether they were found only in 2009 (black), only in 2011 (green), or in both (pink).