HSPG2 and infection: It is worth noting that P. b and P. s may share similar extracellular infection mechanisms with C.p, as evidenced by the presence of three core toxin gene homologs (i.e., colA, pfo and plc) (Table 1), which have been reported to lead to extracellular matrix degradation, cell pore-formation and cell membrane damage in host cells (Popoff and Bouvet, 2009).