Equine platelet lysate exhibits bacteriostatic effects against gram-negative clinical bacterial isolates.

Abstract

BACKGROUND: Investigation of alternative antibiotic therapies is critical for the future of medicine. Platelet lysate (PL) is a blood product that has shown antibiotic potential, which could be used to augment or replace current antibiotics. OBJECTIVES: To compare the effects of equine PL versus antibiotics on growth of clinically isolated antibiotic resistant bacteria. We hypothesized that PL would exert an antimicrobial effect on equine bacterial isolates resistant to antibiotics. METHODS: In vitro experimental study. Platelets were collected via apheresis from nine donor horses and underwent two freeze-thaw cycles. PL was pooled from three different equine donors to create three unique batches. Growth curve and time kill assays were performed on three clinical Enterobacteriaceae-family isolates using 40 % v/v PL treatment, PBS control, or antibiotics as a comparison. Assay results were analyzed statistically across treatments. RESULTS: Bacteria dosed with PL demonstrated a significantly reduced growth rate (mOD/min) over 16-hours compared to control and antibiotics (E. cloacae complex: PL 0.93-1.72; PBS 5.50; ceftiofur 5.84. E. hormachei: PL 0.92-1.58; PBS 5.27; gentamicin 5.13. M. morganii: PL 1.94-2.39; PBS 3.96; TMS 4.04). A mild bactericidal effect (log fold change from 0 hours) was observed after 1 hour (ECC: PL -0.28 - -079; PBS 0.42; ceftiofur 0.1. E. hormachei: PL -0.18 - -0.36; PBS 0.61; gentamicin 0.46. M. morganii: PL -0.09- -0.26; PBS 0.36; TMS 0.11). CONCLUSIONS: PL (40 % v/v) exhibited a bacteriostatic effect on clinical bacterial isolates. PL significantly reduced the number of viable organisms when compared to treatment with antibiotics to which the isolates were resistant.