Assessment of the antimicrobial efficacy and biocompatibility of far-UVC irradiation with whole blood

Owing to its limited penetration, antimicrobial far-UVC light (200 to 230nm) offers a potentially safer alternative to longer-wavelength UV light for tissue-contact decontamination procedures such as wound treatment. Although increasing evidence demonstrates its compatibility with skin and eye tissues, its compatibility with whole blood, and its antimicrobial efficacy within this suspension, remains broadly unknown. This study investigates the antimicrobial efficacy and hemocompatibility of far-UVC light on a panel of wound-relevant bacteria suspended in whole blood, with the aim of identifying antimicrobial light treatment levels that are compatible with whole blood. Ovine whole blood samples (25% PCV; 1.4ml) were inoculated with Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia coli, Enterobacter cloacae, and Enterococcus faecium (103CFU/ml) and irradiated with increasing doses of far-UVC light (~5mW/cm2; peak 221.77nm). Bactericidal doses were then delivered to non-inoculated whole blood, with hemocompatibility quantified via Drabkin’s method of measuring haemolysis and a lipid peroxidation assay (Abcam, UK). Significant reductions (P≤0.05) of all bacteria were demonstrated: however, at bactericidal doses, haemolysis levels were significantly greater compared to non-exposed controls (P