Fatal false‐negative transfusion infection involving a buffy coat platelet pool contaminated with biofilm‐positive <i>Staphylococcus epidermidis</i>: a case report
Bibliographic record
Abstract
BACKGROUND: Bacterial contamination of platelet concentrates (PCs) poses the major posttransfusion infectious risk in developed countries. The aerobic microorganism most frequently isolated from PCs is coagulase-negative Staphylococcus epidermidis, a normal inhabitant of the human skin, which has been involved in fatal transfusion reactions worldwide. CASE REPORT: In September 2014, a splenectomized elderly male patient, suffering from leukemia, was transfused with two 5-day-old buffy coat platelet (PLT) pools. The patient returned to emergency on the same day with a low-grade fever. He was bacteremic and died on the next day. Microbiology and molecular testing of a blood sample from the patient and one of the PCs yielded the same S. epidermidis strain. Further analysis demonstrated that this S. epidermidis isolate displays a biofilm-positive phenotype in PCs. DISCUSSION: At Canadian Blood Services, PCs are screened for bacterial contamination with the BacT/ALERT system (bioMérieux) at approximately 24 hours postcollection. The implicated PC had been tested and yielded a false-negative culture result. A titration experiment indicated that, at the time of screening, the contaminated PC had a titer of less than 0.74 colony-forming units (CFU)/mL (<227 CFUs/unit) of S. epidermidis. Mathematical models have predicted that up to 70% of PCs contaminated with coagulase-negative staphylococci at concentrations of 0.02 CFU/mL can be missed by BacT/ALERT screening. CONCLUSION: Despite several mitigation strategies, false-negative cultures with current PLT screening practices still occur. This report creates awareness of the pathogenicity of opportunistic S. epidermidis, a low-virulence organism, in susceptible patients who may not develop a typical transfusion reaction.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".