In transfusion medicine, bacterial contamination can occur in ex vivo stored blood plasma, and there are continued efforts to improve blood safety and reduce the risk of transfusiontransmitted infections. Visible 405-nm violet-blue light has demonstrated potential for in situ pathogen reduction in ex vivo stored plasma and platelet concentrates. This study investigates the broad-spectrum antibacterial efficacy and compatibility potential of 405-nm light for treatment of blood plasma. Human plasma seeded with bacteria at a range of densities (10 1 -10 3 , 10 4 -10 6 , 10 7 -10 8 CFU mL −1 ) was exposed to 360 J cm −2 405-nm light (1 h at 0.1 W cm −2 ), with this fixed dose selected based on the initial analysis of inactivation kinetics. One-dimensional protein mobility analysis and measurement of advanced oxidation protein products (AOPP) was conducted to evaluate compatibility of the antimicrobial dose with plasma proteins and, identify upper levels at which protein degradation can be detected. Broad-spectrum antibacterial efficacy was observed with a fixed treatment of 360 J cm −2 , with 98.9-100% inactivation achieved across all seeding densities for all organisms, except E. coli, which achieved 95.1-100% inactivation. At this dose (360 J cm −2 ), no signs of protein degradation occurred. Overall, 405-nm light shows promise for broad-spectrum bacterial inactivation in blood plasma, while preserving plasma protein integrity.
The introduction of risk prevention measures, such as blood screening and donor deferrals have dramatically reduced the incidence of transfusion-transmitted viral infections. Nevertheless, bacterial contamination of blood transfusion products remains a concern to patient health, and a range of pathogen reduction technologies have been developed to reduce this risk. Visible violet-blue light, in the region of 405-nm, has recently demonstrated potential for in situ treatment of ex vivo stored plasma and platelet products, without the need for additional photosensitizers.
This study assessed the broad-spectrum efficacy of 405-nm light against a range of bacteria implicated in transfusion-transmitted infections: Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniaeandYersinia enterocolitica. Plasma was seeded with clinically-relevant low-level bacterial contamination (102-103CFUmL-1) and exposed to a 405-nm light dose of 360 Jcm-2 (1-hr at 100mWcm-2) using a small-scale exposure system. Broad spectrum antibacterial efficacy was observed, with 99.0 – 100% inactivation achieved for all bacterial species tested. Bacterial inactivation tests were then scaled-up to expose large volumes of prebagged plasma seeded with S. aureusat ~103 CFUmL-1, to 22mWcm-2 405-nm light, under agitation, (≤396 Jcm-2). Successful bacterial inactivation was observed using the large-scale exposure system, with a dose of 238 Jcm-2 (3-hr at ~22mWcm-2) achieving complete (3.5-log10) reductions in prebagged bacterial-seeded plasma (P=0.001). Results from this study support further development of visible 405-nm light technology as a bactericidal tool for application in transfusion medicine.
This abstract reflects the views of the author and should not be construed to represent FDA’s views or policies.
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