Bacterial screening of outdated buffy coat platelet pools using a culture system and a rapid immunoassay
Bibliographic record
Abstract
BACKGROUND: Canadian Blood Services performs bacterial screening of buffy coat platelet pools (BCPs) using aerobic BacT/ALERT cultures. This study aimed to determine the rate of detection failures during initial platelet (PLT) screening and evaluate the introduction of anaerobic cultures and immunoassay testing to assess the safety of extending PLT storage beyond 5 days. STUDY DESIGN AND METHODS: Outdated (7- to 10-day-old) BCPs that tested negative during initial screening were assayed with BacT/ALERT and the Verax PLT Pan Genera detection (PGD) test, an immunoassay that detects Gram-positive (GP) and Gram-negative (GN) bacteria. BacT/ALERT aerobic and anaerobic culture bottles were inoculated with 8 to 10 mL of BCP and incubated for up to 6 days. The PGD test was performed following manufacturer's instructions. Positive results were confirmed using the BacT/ALERT and PGD tests, blood agar culture, and Gram staining. Invalid PGD results were investigated. RESULTS: A total of 4002 BCPs were tested with one (0.025%) true positive (Staphylococcus epidermidis) found by both the BacT/ALERT and the PGD assays. Fifty-four (1.35%) false-positive BacT/ALERT cultures were obtained mainly due to instrument errors involving anaerobic cultures. Eleven (0.27%) false-positive PGD tests were observed in the GP window of the strip. Forty-nine (1.2%) invalid PGD results were obtained mostly before implementation of a humidity chamber. CONCLUSION: Testing of outdated BCPs suggests that introducing anaerobic cultures would result in significant PLT wastage due to a high rate of false positives. Contaminated BCPs still escape detection during initial testing; therefore, extension of PLT storage may be possible if repeat screening is performed before transfusion.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".