Extension of platelet shelf life with an improved bacterial testing algorithm.

Area of Science:

• Transfusion Medicine
• Microbiology
• Blood Banking

Background:

• Platelet concentrate (PC) shelf life was extended to 7 days at Canadian Blood Services.
• A large-volume, delayed-sampling bacterial screening algorithm was implemented to ensure safety.

Purpose of the Study:

• To present the development study and postimplementation results of an extended PC shelf life bacterial screening algorithm.
• To evaluate the impact of the new screening method on bacterial detection, product outdating, and transfusion safety.

Main Methods:

• Development study involved inoculating PCs with various bacteria and incubating for 7 days with daily sampling.
• Postimplementation analysis included screening 223,156 PC pools and 39,725 apheresis units from August 2017 to December 2019.
• BacT/ALERT cultures and bacterial quantification were used for screening.

Main Results:

• The algorithm detected bacteria like Klebsiella pneumoniae, Serratia marcescens, and Staphylococcus aureus at low concentrations within 24 hours.
• Staphylococcus epidermidis required over 48 hours for detection at low concentrations.
• Postimplementation, confirmed-positive results were 0.09% for pools and 0.04% for apheresis units, predominantly Cutibacterium acnes.
• Combined PC outdating decreased from 18.9% to 13.1%.
• One nonfatal septic reaction occurred with a 7-day PC contaminated with S. epidermidis.
• Septic transfusion events decreased approximately threefold.

Conclusions:

• Screening 7-day PCs enhanced bacterial detection, particularly anaerobes, and reduced product outdating.
• The incidence of septic transfusion events significantly decreased.
• Further surveillance is needed to fully assess the value of anaerobic cultures and residual safety risks.