Platelet aggregation by Streptococcus pyogenes

Abstract

Heat-killed group A Streptococcus pyogenes induced platelet aggregation in platelet-rich plasma. Aggregation was dependent upon the ratio of platelets to bacteria, with maximal aggregation occurring at 0.8 platelets per bacterium (final concentration, 300,000 per ,ul). Inhibition of the reaction by 3 mM EDTA indicated it was a true aggregation and not merely adhesion and agglutination. Lactic acid dehydrogenase assays indicated lysis of platelets did not occur during a 6-min incubation period. Aggregation was inhibited in a dose-dependent manner by acetylsalicylic acid (100 ,uM to 10 mM) and quinacrine (15.6 to 250 ,uM), with no decrease in aggregation at the lowest concentration of inhibitor tested. S. pyogenes induced the release of [14C]serotonin, which was maximal (50%) at 2.4 min, when aggregation was nearly complete. Gel-filtered platelets were not aggregated unless fibrinogen (final concentration, 1.8 mg/ml) was included in the reaction mixture. Staphylococcus aureus, a group B streptococcus, and Escherichia coli were unable to induce aggregation in platelet-rich plasma under the conditions used for S. pyogenes. Thrombocytopenia, thrombophlebitis, and coagulation defects are associated with infectious organisms which initiate the platelet release reaction. In this reaction, stores within platelet granules are released and contribute to fibrin

Platelet Aggregation Induced by Strains of Various Species of Coagulase‐Negative Staphylococci

“…4). By heat treatment at 100 C for 10 min, the potentials of platelet aggregation of S. epidermidis, S. simulans, and S. hyicus were decreased in 65.6% (Pc 0.05), 61.4% 0.05) and 70.9% (P<0.05) compared to those of the controls, respec- (20), group B streptococci (34,36), Viridans group streptococci (31,32), F. necrophorum (9), and H. capsulatum (8) were reported to be inhibited with the addition of arachidonate pathway inhibitors such as ASA, indomethacin, or quinacrine, while those by L. monocytogenes (7), A. .fumigatus (29), C. albicans (30) were not.…”

Platelet Aggregation by Strains of Enterococci

“…In addition, the amount of fibrinogen added to GFP in this study was sufficient for the platelet aggregation by S. aureus (laboratory investigations), which is known to induce platelet aggregation in the presence of fibrinogen in the reaction system (8,28). A majority of the experimental data concerning interaction between bacteria and platelets were collected from strains isolated from infectious foci (35,36) and popular stock strains (8,24,28). Not only the strains used in these experiments, but also other strains randomly collected from fresh isolates induced platelet aggregation (data not shown).…”

“…Among microorganisms possessing the ability to induce platelet aggregation in PRP, Gram-positive cocci, S. aureus, S. sanguis, and group A streptococci have been studied in detail (8,18,24,28,35,36,39,43). Concerning the interaction between enterococci and platelets, more detailed investigations have been needed for comparison with other bacteria-platelets interaction, although Clawson et al (8) reported some properties of the platelet aggregation.…”

“…The mechanisms of platelet aggregation by these stimuli have been studied in detail (16). In contrast to these effects favorable for hemostasis, platelets also possess a pathogenic significance in disseminated intravascular coagulation (DI C) during sepsis or infective endocarditis (3,7,22,30) and observations have been made concerning the relationship between the platelet and several species of microorganisms, Staphylococcus aureus (8,18,28,40), coagulasenegative staphylococci (CNS) (41), streptococci (24,35,36,39,43), Listeria monocytogenes (9), Fusobacterium necrophorum (15), Aspergillus fumigatus (31), Candida albicans (33), Histoplasma capsulatum (10).…”

Minimizing the Diameter of Electrospun Polyacrylonitrile (PAN) Nanofibers by Design of Experiments for Electrochemical Application

“…Depending on the composition, dimension, morphology and physical, chemical, biological, and material properties, nanofibers can be an attractive structure for nanotechnology due to their size-dependent properties, ultra-high surface area-to-volume ratio, and ability to interface nano to macro world. Carbon nanofibers (CNFs) are further categorized as excellent material for electrodes, interconnections and gate in nanoelectronics, fillers in nanocomposite materials, and catalysis applications [1][2][3][4][5].…”