S. epidermidis forms biofilms on PLT aggregates and on PLT bags under PLT storage conditions. Our results demonstrate that the PLT storage environment can promote a BF growth mechanism for contaminant bacteria.

whole-blood-derived PCs and apheresis PCs are stored up to 5 days.

No abstract

Background: At Canadian Blood Services, platelet concentrate (PC) shelf life was extended to 7 days with a large-volume, delayed-sampling bacterial screening algorithm. We present the development study and postimplementation results. Study Design and Methods: In the development study, PCs inoculated with five bacteria (various concentrations) were incubated for 7 days with daily sampling for BacT/ALERT cultures and bacterial quantification. After implementation, from August 2017 to December 2019, a total of 223 156 pools and 39 725 apheresis units and 5310 outdated PCs were screened. Since March 2018, cocomponents associated to false-positive results have been released to inventory. Results: In the development study, Klebsiella pneumoniae, Serratia marcescens, and Staphylococcus aureus were detected at concentrations of at least 0.01 colony-forming units (CFUs)/mL at 24 hours postinoculation. However, Staphylococcus epidermidis was detected at concentrations of less than 0.16 CFUs/mL only more than 48 hours postinoculation. After implementation, 776 (0.35%) and 303 (0.77%) initial-positive results and 201 (0.09%) and 16 (0.04%) confirmed-positive results were obtained for pools and apheresis units, respectively, predominantly with Cutibacterium acnes. Other organisms included staphylococci, streptococci, Klebsiella oxytoca and Pseudomonas aeruginosa. One nonfatal reaction involving a 7-day pool contaminated with S. epidermidis occurred. Approximately, 1-in-1000 false-negative screening results were obtained during testing of outdated PCs. Approximately 1000 cocomponents associated with false-positive results were released into inventory. Combined PC outdating at Canadian Blood Services and hospitals was reduced from 18.9% to 13.1%. Conclusion: Screening of 7-day PCs increased bacterial detection mainly of anaerobes and reduced outdating. The incidence of septic transfusion events has decreased approximately threefold. A longer surveillance period is needed to evaluate the value of anaerobic cultures and residual safety risk.

The bulk of coagulation factor activity losses during storage occurred in the first 24 hours. Coagulation factor activities remaining in FP after 5 days did not differ from those previously reported in similar products frozen within 24 hours of phlebotomy. While DEHP levels in 5-day-thawed FP are not of concern for adult patients, for infants, DEHP levels can be minimized by using FP refrigerated for no more than 24 hours.

Single or multiple RT exposures did not affect RBC quality but slightly promoted bacterial growth in contaminated units. The clinical significance of these results remains unclear and needs further investigation.

McFarland Turbidity Standards and the Densimat photometer were compared for their accuracy to adjust bacterial suspensions. Six bacterial species were tested with both methods. Statistical analyses showed that adjusting bacterial suspensions with the Densimat photometer results in less variation within assays and in a more accurate determination of bacterial inocula.

Visual inspection of blood components before transfusion is an essential safety practice to interdict the transfusion of bacterially contaminated units.