Antimicrobial properties of platelet rich plasma (PRP) against various microorganisms have been recently pointed out. PRP could be an alternative to conventional antibiotics in preventing oral and periodontal infections. We examined whether PRP has in vitro antimicrobial properties against Aggregatibacter actinomycetemcomitans, Prophyromonas gingivalis, Staphylococcus aureus and Candida albicans. PRP and platelet-poor plasma (PPP) were obtained from whole blood of 10 healthy volunteers and 10 periodontitis patients. In vitro laboratory susceptibility was carried out using the modified agar diffusion method by measuring the diameters of inhibition zones on agar plates coated with selected microbial strains. Both calcium chloride (CaCl2) activated and non activated samples were tested. Both activated PRP and PPP, of both patients and controls, effectively inhibited the growth of A. actinomycetemcomitans, P. gingivalis and C. albicans. However, a statistically significant difference in favor of PRP was found indicating more susceptibility to PRP than PPP (p < 0.05). Non activated PRP and PPP exhibited negative zones of inhibition against the studied microorganisms. There was no activity against S. aureus. No statistically significant difference was found between the antimicrobial effects of PRP and/or PPP obtained from patients and controls (p > 0.05). We conclude that PRP is a potentially useful substance against oral and periodontal pathogens. Activated PRP was found to be more active than activated PPP and the activation of coagulation is a fundamental step. Additionally, the antimicrobial activity of PRP and/or PPP seems not to be affected by periodontitis.
