Photochemical treatment of platelet concentrates with amotosalen and long-wavelength ultraviolet light inactivates a broad spectrum of pathogenic bacteria

BACKGROUND: Bacterial contamination of platelet (PLT) concentrates can result in transfusion-transmitted sepsis. A photochemical treatment (PCT) process with amotosalen HCl and long-wavelength ultraviolet light (UVA), which cross-links nucleic acids, was developed to inactivate bacteria and other pathogens in PLT concentrates. STUDY DESIGN AND METHODS: High titers of pathogenic aerobic and anaerobic Gram-positive bacteria (10 species), aerobic Gram-negative bacteria (7 species), and spirochetes (2 species) were added to single-donor PLT concentrates containing 3.0 x 10(11) to 6.0 x 10(11) PLTs in approximately 300 mL of 35 percent plasma and 65 percent PLT additive solution (InterSol, Baxter Healthcare) or saline. After PCT with 150 mumol per L amotosalen and 3 J per cm(2) UVA, residual bacterial levels were detected by sensitive microbiologic methods. RESULTS: The level of inactivation of viable bacteria was expressed as log reduction. Log reduction of Gram-positive bacteria for Staphylococcus epidermidis was > 6.6; for Staphylococcus aureus, 6.6; for Streptococcus pyogenes, > 6.8; for Listeria monocytogenes, > 6.3; for Corynebacterium minutissimum, > 6.3; for Bacillus cereus (vegetative), > 5.5; for Lactobacillus sp., > 6.4; for Bifidobacterium adolescentis, > 6.0; for Propionibacterium acnes, > 6.2; and for Clostridium perfringens, > 6.5. Log reduction of Gram-negative bacteria for Escherichia coli was > 6.4; for Serratia marcescens, > 6.7; for Klebsiella pneumoniae, > 5.6; for Pseudomonas aeruginosa, 4.5; for Salmonella choleraesuis, > 6.2; for Yersinia enterocolitica, > 5.9; and for Enterobacter cloacae, 5.9. Log reduction of spirochetes for Treponema pallidum was 6.8 to 7.0, and for Borrelia burgdorferi, > 6.9. CONCLUSION: PCT inactivates high levels of a broad spectrum of pathogenic bacteria. The inactivation of bacteria in PLT concentrates offers the potential to prospectively prevent PLT-transfusion-associated bacteremia.