The Interactions Between Bacteria, Platelets Bags and Platelets

Wilson-Nieuwenhuis, Joels (2018) The Interactions Between Bacteria, Platelets Bags and Platelets. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Bacterial contamination of blood products is a major risk in transfusion medicine, with bacterial attachment and biofilm formation a potential source for false negative results of bacterial platelet contamination. Understanding platelet bag (PB) surface properties could improve understanding of how bacteria adhere to these surfaces. PB surfaces were analysed using scanning electron microscopy, optical surface profiling, Fourier transform infrared spectroscopy, RAMAN spectroscopy, goniometry, energy dispersive X-ray and a tensiometer. Initial findings demonstrated that the PBs had two distinct surfaces, a rough diamond patterned surface and a smoother surface. Two surface altering methods were used; PBs surfaces were flattened to remove surface features, which can increase bacterial attachment, and treated with low temperature atmospheric pressure plasma, with flattening demonstrating surface feature changes and plasma treatment being unsuitable. Staphylococcus epidermidis and Serratia marcescens biofilms grown on the surfaces demonstrated reduced biomass formation on the flattened surface after 5 days. Conditioning films on the surfaces of the bacteria, human plasma and human plasma combined with one of the bacteria demonstrated that the human plasma alone altered the surface properties the most, especially the roughness, surface chemistry and surface physicochemistry. When human plasma was combined with bacteria, changes were also determined but differed to when human plasma was tested alone. Finally, testing the effects of bacteria on platelets demonstrated that planktonic bacteria had little effect on platelet activation and viability, whilst biofilms halved platelet aggregation but did not affect activation. Western blots demonstrated that protein expression could be affected, particularly by biofilms. Further, release of RANTES by the platelets was doubled when incubated with bacterial biofilms. The results demonstrated the significance surface properties had on bacterial attachment and biofilm formation as well as how conditioning films altered the surface properties and how biofilms were able to affect platelets.