Objective Platelet-Rich Plasma(PRP) is widely used to promote wound healing and tissue regeneration. The aim of the study was to explore the antimicrobial properties of blood products against free bacteria and bacteria-forming biofilm commonly found in burn wound.
Methods In vitro studies were conducted to test isolated neutrophils, PRP, Platelet Poor-Plasma (PPP) and Leucocyte and PRP(L-PRP)against planktonic Staphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter baumannii.Blood products were obtained from eight healthy volunteers. Neutrophils were isolated using a Percoll density gradient method, PRP products were obtained using a sterile centrifugation technique. Components of products were confirmed using a full blood analyser(Sysmex XN1000).Assays to determine microbicidal and cytostatic properties of the preparations included disk diffusion, and growth kinetics. The ability of the blood-derived products to prevent P. aeruginosa and A. baumannii biofilm formation was tested using crystal violet biofilm formation assays and the biomass read as level of absorbance.Linear mixed models, ANOVA, Levene’s test were used.
Results Isolated neutrophils did not show bacterial growth inhibition compared to control. The only preparation showing growth control of S. aureus was the L-PRP preparation, where the leukocyte and neutrophil content of the preparation both significantly slowed bacterial growth kinetics.PRP and PPP preparations significantly reduced Pseudomonas and Acinetobacter growth over a 12-hours period compared to the positive control(p-value <0.0001). Against the Gram-negative bacteria, all the biomaterials tested gave a reduced level of biofilm biomass formation compared to positive control(Donor 1: activated L-PRP, L-PRP, PRP vs Acinetobacter in broth p < 0.0001, and PPP p < 0.05. All blood-derived products vs Pseudomonas p <0.0001).
Discussion Blood-derived products showed different antimicrobial properties according to the bacterial target and the cellular composition of the product tested. This in-vitro study provides preliminary evidence that blood-derived products can inhibit growth of key burn wound pathogens, both in their planktonic and biofilm forms.

Antimicrobial properties of blood-derived products against biofilm-forming bacteria commonly found in burn wounds