Schematic representation of platelet activation cascade induced by bacteria. Bacteria-bound PF4 is recognized by plasma IgG and this complex binds to platelet FcγRIIA receptor, thereby inducing a mild inside-out signaling leading to integrin αIIbβ3 activation. Fibrinogen binding to the activated αIIbβ3 results in granular secretion. ADP secreted from δ-granules provides positive feedback. PF4 secreted from α-granules potentiates further binding of additional bacteria.