Antimicrobial activity of turtle thrombocyte-leukocyte rich plasma and acellular plasma on bacterial isolates from reptile infected wounds

Autologous platelet concentrates are widely used in mammalian regenerative medicine due to their high content of bioactive molecules derived from platelets that promote wound healing. In addition, in recent years the antimicrobial activity of platelet concentrates against various bacteria has been highlighted. Recently, platelet concentrates have found clinical applications in tissue repair in unconventional companion animals, such as turtles, which are often subject to traumatic injuries. The aim of this study was to optimize a protocol for the preparation of turtle thrombocyte and leukocyte-rich plasma (TLRP) and to evaluate the antimicrobial activity of turtle TLRP and acellular plasma or platelet-poor plasma (PPP) against bacteria isolated from infected wounds of reptiles. The antimicrobial activity was preliminarily evaluated through the Kirby-Bauer test on the following bacteria: Morganella morganii, Klebsiella oxytoca, Pseudomonas oryzihabitans, Staphylococcus xylosus, Micrococcus spp., Staphylococcus auricularis, Alcaligenes faecalis, Citrobacter spp., Pseudomonas aeruginosa, Staphylococcus aureus ATCC 25923 e Pseudomonas aeruginosa ATCC 27853. Subsequently, the minimum inhibitory concentration (MIC) and a time-kill assay were performed on Citrobacter spp., Klebsiella oxytoca and Staphylococcus xylosus. Our results showed that, in order to obtain an optimal recovery of thrombocytes (TT) and leukocytes (LL), the centrifugation conditions for each passage required by the protocol for the preparation of TLRP, in terms of time and centrifugal force, must be carefully settled. Kirby-Bauer assay showed inhibition halos, ranging from 7.6 mm to 6.8 mm, by turtle PPP and TLRP against Citrobacter spp. and Klebsiella oxytoca. The turtle PPP showed a MIC equal to 4 and a complete bactericidal activity at 2 hours of incubation against Citrobacter spp. The other platelet derivatives tested (TLRP, PRP and PPP of dog) did not showed antimicrobial activity against any of the bacterial strains tested in MIC and time-kill tests. In conclusion, our results showed that the correct evaluation of centrifugation force and time is an important factor affecting the final yield of TT/LL in TLRP. Moreover, the PPP of turtle showed a high bactericidal activity against Citrobacter spp. and this could potentially find a useful application in the treatment of septicemic cutaneous ulcerative disease (SCUD), an important pathology of turtles