Characterization of transfusion-relevant bacteria reference strains in a lyophilized format.

Background and Objectives: Blood safety measures used by blood establishments to increase blood component safety can be validated using Transfusion-Relevant Bacterial Reference Strains (TRBRS). Ultra-cold storage conditions and manual preparation of the current TRBRS may restrict their practical use. To address this issue, the ISBT Transfusion-Transmitted Infectious Diseases Working Party's Bacterial Subgroup organized an international study to validate TRBRS in a user-friendly, lyophilised format.
Materials and Methods: Two bacterial strains Klebsiella pneumoniae PEI-B-P-08 and Staphylococcus aureus PEI-B-P-63 were manufactured as lyophilised material. The lyophilised bacteria were distributed to 11 different labs worldwide to assess the robustness for enumeration, identification and determination of growth kinetics in platelet concentrates (PCs).
Results: Production of lyophilised TRBRS had no impact on the growth properties compared with the traditional format. The new format allows a direct low-quantity spiking of approximately 30 bacteria in PCs for transfusion-relevant experiments. In addition, the lyophilised bacteria exhibit long-term stability across a broad temperature range and can even be directly rehydrated in PCs without losing viability. Interlaboratory comparative study demonstrated the robustness of the new format as 100% of spiked PC exhibited growth.
Conclusion: Lyophilised TRBRS provide a user-friendly material for transfusion-related studies. TRBRS in the new format have improved features that may lead to a more frequent use in the quality control of transfusion-related safety measures in the future.
(© 2024 The Authors. Vox Sanguinis published by John Wiley & Sons Ltd on behalf of International Society of Blood Transfusion.)