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Photochemical inactivation of pathogenic bacteria in human platelet concentrates
Abstract:
Platelet concentrates (PC) may be infrequently contaminated with low levels of bacteria that can cause septicemia and death in patients receiving transfusion therapy. We evaluated the efficacy of a photochemical decontamination (PCD) technique using 8-methoxypsoralen (8-MOP) and long wavelength UV light (UVA) to inactivate bacteria in standard therapeutic PC. Twelve phylogenetically distinct pathogenic bacteria, 5 gram-positive and 7 gram-negative organisms, were seeded into PC to a final challenge dose ranging from 10(5) to 10(7) colony-forming units (CFU)/mL. Contaminated PC were treated with 8-MOP (5 micrograms/mL) and 5 J/cm2 of UVA, a PCD treatment regimen found to adequately preserve in vitro platelet function. Greater than 10(5) CFU/mL of all 5 gram-positive (Staphylococcus aureus, Streptococcus epidermidis, Streptococcus pyogenes, Listeria monocytogenes, and Corynebacterium minutissimum) and 2 of the gram-negative (Escherichia coli and Yersinia enterocolitica) organisms were inactivated. The remaining 5 gram-negative organisms were more resistant, with less than 10(1) to 10(3.7) CFU/mL inactivated under these conditions. The inactivation efficiency for this resistant group of gram-negative organisms was improved when PC were resuspended in a synthetic storage medium with reduced plasma protein concentration (15%) and an increased 8-MOP concentration (23.4 micrograms/mL). Illumination with 3 J/cm2 of UVA in this system inactivated greater than 10(5) CFU/mL of 4 resistant gram-negative organisms (Salmonella choleraesuis, Enterobacter cloacae, Serratia marcescens, and Klebsiella pneumoniae) and 10(4.1) CFU/mL of the most resistant gram-negative organism (Pseudomonas aeruginosa). This level of PCD treatment did not adversely affect in vitro platelet function. These results demonstrate that PCD using 8-MOP (5 to 23.4 micrograms/mL) effectively inactivated high levels of pathogenic bacteria in PC with adequate preservation of in vitro platelet properties.
Insights
Photochemical decontamination (PCD) effectively inactivates bacteria in platelet concentrates (PC). This method, using 8-methoxypsoralen (8-MOP) and UV light (UVA), ensures safe transfusion therapy by eliminating pathogens while preserving platelet function.
Area of Science:
- Transfusion Medicine
- Microbiology
- Biotechnology
Background:
- Platelet concentrates (PC) can be contaminated with bacteria, posing a risk of septicemia and death in transfusion recipients.
- Existing decontamination methods may compromise the quality and efficacy of platelet products.
- There is a critical need for effective methods to eliminate bacterial contamination in PC without impairing platelet function.
Purpose of the Study:
- To evaluate the efficacy of a photochemical decontamination (PCD) technique using 8-methoxypsoralen (8-MOP) and UVA light for inactivating bacteria in therapeutic platelet concentrates (PC).
- To assess the impact of PCD treatment on the in vitro function of platelets.
- To optimize PCD parameters for enhanced inactivation of resistant bacterial strains.
Main Methods:
- Twelve phylogenetically distinct pathogenic bacteria were inoculated into PC at concentrations ranging from 10^5 to 10^7 CFU/mL.
- PC were treated with 8-MOP (5 µg/mL) and 5 J/cm² UVA, a regimen preserving platelet function.
- Optimized conditions involved resuspending PC in a synthetic medium with reduced plasma protein (15%) and increased 8-MOP (23.4 µg/mL), followed by 3 J/cm² UVA illumination.
Main Results:
- PCD inactivated >10^5 CFU/mL of all 5 gram-positive and 2 gram-negative bacteria tested.
- 5 gram-negative organisms showed resistance, with inactivation ranging from <10^1 to 10^3.7 CFU/mL.
- Optimized PCD conditions inactivated >10^5 CFU/mL of 4 resistant gram-negative strains and 10^4.1 CFU/mL of Pseudomonas aeruginosa, without affecting platelet function.
Conclusions:
- Photochemical decontamination using 8-MOP and UVA is effective in inactivating high levels of pathogenic bacteria in platelet concentrates.
- Optimized PCD protocols can overcome resistance in certain gram-negative bacteria.
- The PCD technique adequately preserves in vitro platelet function, offering a promising strategy for pathogen-reduced platelet products.