Platelet aggregation induced by strains of various species of coagulase-negative staphylococci.

Major species of coagulase-negative staphylococci (CNS) were tested for their ability to induce platelet aggregation in rabbit platelet-rich plasma (PRP). Among 11 species of CNS tested, a majority of the strains of 10 species of CNS (S. epidermidis, S. simulans, S. capitis, S. hyicus, S. sciuri, S. cohnii, S. xylosus, S. hominis, S. haemolyticus, S. warneri) caused induction of the platelet aggregation and serotonin release, while S. saprophyticus did not show such activity. The addition of aspirin (10 mM) or quinacrine (1 mM) to PRP resulted in no remarkable effect on the platelet aggregation induced by these strains and it was shown that the platelet aggregation did not require arachidonate pathways. Complement system components were shown to be one of the plasma factors required for platelet aggregation by ten strains of each species of CNS. The bacterial substance participating in the platelet aggregation by ten species of CNS tested was indicated to be heat-stable and trypsin-resistant, while the activity of a strain of S. epidermidis was susceptible to trypsin.