(P-TS-49) INTERCEPT Treatment of Contaminant Bacteria Enterobacter soli, Leclercia adecarboxylata, and Staphylococcus saprophyticus in Human Apheresis Platelets

Background/Case Studies: The INTERCEPT® Blood System for Platelets is a pathogen reduction technology that inactivates pathogens and leukocytes using amotosalen and UVA light. The system is used in the United States and Europe to treat apheresis- and whole-blood derived platelets.
Enterobacter soli, Leclercia adecarboxylata, and Staphylococcus saprophyticus were isolated from an INTERCEPT-treated apheresis platelet unit that was involved in a transfusion-transmitted infection in a clinic in the United States. Whether the unit was contaminated post-pathogen reduction was unclear as the bag was discarded before analysis could be performed. However, previous data have shown that both L. adecarboxylata and S. saprophyticus are inactivated by the INTERCEPT Blood System for Platelets (Fadeyi et al., 2020). There are no inactivation data for E. soli and no E. soli transfusion-transmitted infections have been previously reported.

Study

Design/Methods: The aim of this study was to assess the inactivation of E. soli alone and in combination with L. adecarboxylata and S. saprophyticus in apheresis platelets using the INTERCEPT Blood System for Platelets. To measure pathogen inactivation, 3.4 mL of an overnight culture of E. soli or a 1:1:1 (volume) mixture of E. soli, L. adecarboxylata, and S. saprophyticus were inoculated into an apheresis platelet unit (35% plasma/65% platelets) and treated using the INTERCEPT Dual Storage Platelet Processing Set by amotosalen and UVA light. The unit was incubated in the compound adsorption device (CAD) container for 16 h at 22°C and then transferred into storage bags for incubation at 22°C with shaking. Bacterial titer was determined pre-treatment and post-treatment on day 5- and 7-post collection. On day 7, residual bacterial titer was determined by combining the remaining unit with LB broth and incubating in a flask overnight at 37°C.

Results/Findings: INTERCEPT treatment inactivated 7.5 ± 0.1 log CFU/mL of E. soli alone and 7.2 ± 0.1 log CFU/mL of the combination of E. soli, L. adecarboxylata, and S. saprophyticus. No detectable bacteria were observed post-treatment, at 5- and 7-days post-collection in either case.

Conclusions: We show in this study that INTERCEPT treatment can inactivate E. soli, L. adecarboxylata, and S. saprophyticus achieving sterility throughout the 7-day storage period. Previous reports of TTIs involving an INTERCEPT-treated unit have shown defects in the storage containers that presumably allowed contamination during storage (Fadeyi et al., 2020). Further studies are required to understand how units can be contaminated during the storage period.

Importance of research: This study shows pathogen reduction data for 3 contaminants of an apheresis platelet unit: Enterobacter soli, Leclercia adecarboxylata, and Staphylococcus saprophyticus. Enterobacter soli has not been reported in a transfusion-transmitted infection prior to this data. Data shows the INTERCEPT Blood System for Platelets can inactivate 7.5 ± 0.1 log CFU/mL of Enterobacter soli alone and 7.2 ± 0.1 log CFU/mL of combined Enterobacter soli, Leclercia adecarboxylata, and Staphylococcus saprophyticus.