Different strains of GBS induced platelets aggregation in vitro. Plasma incubated with PBS as negative control (A). Plasma incubated with ADP as positive control (B). Plasma incubated with GBS 255 (C), GBS 639 (D), GBS 945 (E), GBS 81875 (F), GBS 90604 (G) and GBS 93555 (H).