Effect of antiplatelet agents on platelet antistaphylococcal capacity: An in vitro study

The involvement of platelets in anti-infectious immunity has been widely demonstrated. Molecules secreted mainly by α-granules are involved in reducing the growth of certain bacterial species. However, the effect of antiplatelet treatments on the platelet antibacterial ability remains poorly understood. This study aimed to evaluate the platelet antibacterial effect against Staphylococcus aureus and to evaluate the influence of antiplatelet drugs on this effect. Blood samples were collected from healthy donors or patients treated with antiplatelet therapy. Six S. aureus strains were included. Bacteria were incubated with platelets for 4 h. Colonies were counted on blood agar. The supernatant's effect was evaluated. The effect of in vitro antiplatelet agents and salicylic acid was also tested. The CD62P expression rate was evaluated under different conditions of infection and platelet treatment. Platelets slowed the growth of the six S. aureus strains (P = 0.006 for P6134, P = 0.001 for P6170 and P6138, and P = 0.003 for the other strains versus bacteria alone). The supernatant of platelets pre-infected with bacteria and that of platelets pre-treated with TRAP retained this antibacterial effect (platelet-bacteria supernatant, P = 0.018; TRAP, P = 0.011 versus bacteria alone). Treatment of platelets by antiplatelet drugs significantly decreased this antibacterial effect (aspirin, P = 0.027; ticagrelor, P = 0.0263; combination, P = 0.0092 versus untreated platelets). Salicylic acid also induced inhibition of this antibacterial effect (P = 0.042 versus untreated platelets). This study showed that antiplatelet agents decreased the antibacterial effect of platelets against S. aureus.