Alignment of the capsular biosynthetic loci between ST320 MDR19A in the post-PCV7 introduction era and pre-PCV7 MDR19F. The capsule locus resides between genes aliA and dexB. The vex operon was present directly adjacent to the capsule locus of 19A but not 19F. Of note are the genes pbp2x and pbp1a, responsible for penicillin resistance, that are present adjacent to the capsule locus. For a full image of the capsule locus and flanking regions please see Additional file 8http://www.pillailab.com/suppdata/index.html.