Effect of Streptococcus sanguinis/Porphyromonas gingivalis single and combined biofilms upon platelet aggregation

Oral Diseases (2012) 18, 586–594 Objective: To assess the effect of two oral bacteria Streptococcus sanguinis and Porphyromonas gingivalis upon platelet aggregation. Materials and Methods: Streptococcus sanguinis, P. gingivalis, S. sanguniis + P. gingivalis were added to platelet‐rich plasma and platelet aggregation measured using a platelet aggregometer. Platelets were passed through a flow chamber with S. sanguinis, P. gingivalis or a biofilm of S. sanguinis and P. gingivalis coated with saliva. Platelet adhesion to the chamber was observed under a fluorescence microscope for 15 min. The positive control was platelets treated with adrenaline; the negative control was platelets treated with phosphate‐buffered saline. Results: The mean (± s.e.) aggregation magnitude of S. sanguinis and P. gingivalis was 77.7 ± 7.4% and 79.3 ± 9.9%, respectively. The aggregation magnitude of S. sanguinis + P. gingivalis was 51.3 ± 12.9%, which was significantly lower than that for S. sanguinis/P. gingivalis (P < 0.05). In the flow chamber system, platelets adhered to S. sanguinis/P.gingivalis respectively within 3 min, and reached a plateau at 5–15 min. Under the condition of the S. sanguinis‐ and P. gingivalis‐saliva biofilm, platelet adhesion to the biofilm was significantly reduced at 5–15 min (P < 0.05). Conclusions: In the static or dynamic flow system, platelets adhered to S. sanguinis or P. gingivalis. However, if S. sanguinis was mixed with P. gingivalis, the aggregation magnitude (%) was significantly reduced.