Yuntong Kou

Fatal false-negative transfusion infection involving a buffy coat platelet pool contaminated with biofilm-positive Staphylococcus epidermidis: a case report.

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.

Evaluating the 4‐hour and 30‐minute rules: effects of room temperature exposure on red blood cell quality and bacterial growth

BACKGROUND: A 30‐minute rule was established to limit red blood cell (RBC) exposure to uncontrolled temperatures during storage and transportation. Also, RBC units issued for transfusion should not remain at room temperature (RT) for more than 4 hours (4‐hour rule). This study was aimed at determining if single or multiple RT exposures affect RBC quality and/or promote bacterial growth.

Bacterial screening of outdated buffy coat platelet pools using a culture system and a rapid immunoassay

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.

Bacterial growth in red blood cell units exposed to uncontrolled temperatures: challenging the 30-minute rule.

The ‘30‐min rule’ requires discarding red blood cells (RBCs) exposed to uncontrolled temperatures for >30 min to ensure safe RBC transfusion. This study was aimed at determining whether multiple room temperature (RT) exposures promote bacterial growth.

Evaluation of a universal point‐of‐issue assay for bacterial detection in buffy coat platelet components

Bacterial contamination of platelet concentrates poses a major post‐transfusion infectious risk. This study was aimed at evaluating the efficacy of the BacTx® assay (Immunetics Inc.) for bacterial detection in leucocyte‐reduced buffy coat platelet pools and for its sensitivity in detecting clinical isolates, including bacteria that form surface‐attached aggregates (biofilm positives). Platelet pools were inoculated at bacterial concentrations of 0·8–13 CFU/ml. The BacTx® assay detected all species at concentrations ≥103 CFU/ml within 20–69 h of platelet incubation. Detection of slow‐growing and biofilm‐forming strains was delayed in comparison with the other strains. This assay could be used as a point‐of‐issue method to increase the safety of the platelet supply.

Validation of sterility testing of cord blood: challenges and results

Sterility testing for cord blood (CB) products is mandatory to prevent transplantation‐transmitted microbial infections. Here, the automated BacT/ALERT (bioMérieux) culture system was validated to detect microbial contamination in CB units processed at the Canadian National Public Cord Blood Bank.

Septic transfusion case caused by a platelet pool with visible clotting due to contamination with Staphylococcus aureus

Contamination of platelet concentrates (PCs) with Staphylococcus aureus is one of the most significant ongoing transfusion safety risks in developed countries.

Comparative characterisation of the biofilm-production abilities of Staphylococcus epidermidis isolated from human skin and platelet concentrates

Purpose. Staphylococcus epidermidis is the predominant contaminant of platelet concentrates (PCs), a blood product used to treat patients with platelet deficiencies. This microorganism is able to form surface‐attached aggregates (biofilms) in human skin. Herein, the abundance of S. epidermidis biofilm‐producers in contaminated PCs compared to skin isolates was explored. Furthermore, the potential positive selection of S. epidermidis biofilm‐producers during the blood donation process and PC manufacturing was investigated. Methodology. Twenty‐four S. epidermidis isolates obtained from contaminated PCs and 48 S. epidermidis isolates obtained from the venipuncture area of human volunteers were compared for their ability to form biofilms in laboratory media and in PCs using a semi quantitative crystal violet assay. Also, the presence of the biofilm‐associated icaA and icaD genes was assessed by PCR‐amplification. Results/Key findings. Biofilm production in laboratory media showed a higher number of S. epidermidis biofilm‐producers in the skin‐derived group (43.7 %) compared to the PC‐derived isolates (25 %). However, all skin and PC isolates formed biofilms in PCs. The prevalence of ica‐positive biofilm‐producer isolates was similar in PC and skin isolates (16.6 and 18.8 %, respectively). In contrast, the abundance of ica‐negative biofilm‐producers was lower in PC isolates compared to skin isolates (8.3 vs 25 %, respectively). Conclusion. Positive selection of S. epidermidis biofilm‐producers during blood donation and PC manufacturing was not observed. Interestingly, ica‐negative biofilm‐producers seem to be negatively affected by skin disinfection, blood processing and PC storage. Furthermore, this study shows that S. epidermidis adopts a biofilm‐forming phenotype in PCs regardless of its genetic background or origin.

Noninvasive pH monitoring for bacterial detection in platelet concentrates

Bacterial contamination of platelet concentrates (PCs) remains the prevalent posttransfusion infectious risk. The pH SAFE system, a noninvasive method used to measure pH of PC for quality control, was evaluated herein as a rapid method to detect bacterial contamination in PCs.