Association of Staphylococcus aureus in platelet concentrates with skin diseases in blood donors: Limitations of cultural bacterial screening

Modulation of Staphylococcus aureus gene expression during proliferation in platelet concentrates with focus on virulence and platelet functionality

Staphylococcus aureus is a well-documented bacterial contaminant in platelet concentrates (PCs), a blood component used to treat patients with platelet deficiencies. This bacterium can evade routine PC culture screening and cause septic transfusion reactions. Here, we investigated the gene expression modulation within the PC niche versus trypticase soy media (TSB) of S. aureus CBS2016-05, a strain isolated from a septic reaction, in comparison to PS/BAC/317/16/W, a strain identified during PC screening. RNA-seq analysis revealed upregulation of the capsule biosynthesis operon (capA-H), surface adhesion factors (sasADF), clumping factor A (clfA), protein A (spa), and anaerobic metabolism genes (pflAB, nrdDG) in CBS2016-05 when grown in PCs versus TSB, implying its enhanced pathogenicity in this milieu, in contrast to the PS/BAC/317/16/W strain. Furthermore, we investigated the impact of S. aureus CBS2016-05 on platelet functionality in spiked PCs versus non-spiked PC units. Flow cytometry analyses revealed a significant decrease in glycoprotein (GP) IIb (CD41) and GPIbα (CD42b) expression, alongside increased P-selectin (CD62P) and phosphatidylserine (annexin V) expression in spiked PCs compared to non-spiked PCs (p = 0.01). Moreover, spiked PCs exhibited a drastic reduction in MitoTrack Red FM and Calcein AM positive platelets (87.3% vs. 29.4%, p = 0.0001 and 95.4% vs. 24.7%, p = 0.0001) in a bacterial cell density manner. These results indicated that S. aureus CBS2016-05 triggers platelet activation and apoptosis, and compromises mitochondrial functionality and platelet viability, in contaminated PCs. Furthermore, this study enhanced our understanding of the effects of platelet-bacteria interactions in the unique PC niche, highlighting S. aureus increased pathogenicity and deleterious effect on platelet functionality in a strain specific manner. Our novel insights serve as a platform to improve PC transfusion safety.

Characterization of transfusion-relevant bacteria reference strains in a lyophilized format

BACKGROUND AND OBJECTIVES

Blood safety measures used by blood establishments to increase blood component safety can be validated using Transfusion-Relevant Bacterial Reference Strains (TRBRS). Ultra-cold storage conditions and manual preparation of the current TRBRS may restrict their practical use. To address this issue, the ISBT Transfusion-Transmitted Infectious Diseases Working Party's Bacterial Subgroup organized an international study to validate TRBRS in a user-friendly, lyophilised format.

MATERIALS AND METHODS

Two bacterial strains Klebsiella pneumoniae PEI-B-P-08 and Staphylococcus aureus PEI-B-P-63 were manufactured as lyophilised material. The lyophilised bacteria were distributed to 11 different labs worldwide to assess the robustness for enumeration, identification and determination of growth kinetics in platelet concentrates (PCs).

RESULTS

Production of lyophilised TRBRS had no impact on the growth properties compared with the traditional format. The new format allows a direct low-quantity spiking of approximately 30 bacteria in PCs for transfusion-relevant experiments. In addition, the lyophilised bacteria exhibit long-term stability across a broad temperature range and can even be directly rehydrated in PCs without losing viability. Interlaboratory comparative study demonstrated the robustness of the new format as 100% of spiked PC exhibited growth.

CONCLUSION

Lyophilised TRBRS provide a user-friendly material for transfusion-related studies. TRBRS in the new format have improved features that may lead to a more frequent use in the quality control of transfusion-related safety measures in the future.

Septic Transfusion Reactions Involving Burkholderia cepacia Complex: A Review

This review was conducted to assess the global incidence of transfusion-transmitted infections (TTIs) caused by contamination of blood components with the Burkholderia cepacia complex (Bcc). Our search encompassed various specialized databases such as Medline/PubMed, Web of Science, Scopus, Scielo, ScienceDirect, and ClinicalKey. An analysis of the literature revealed a total of eleven reported cases where blood components contaminated with Bcc had been transfused, resulting in sepsis among the affected patients. Of these cases, eight were documented in the literature, while the remaining three occurred within the institution involving the authors of this review. A comparative examination was conducted, considering factors such as primary diagnosis, transfused blood component, time elapsed between transfusion and manifestation of symptoms, administration of antibiotics, and final outcome. Interestingly, regardless of the storage temperature, all blood components were found to be susceptible to Bcc contamination. Furthermore, the cases investigated revealed diverse sources of contamination, and it was observed that all the affected patients had compromised immune systems due to underlying illnesses. Based on these findings, a series of preventive strategies were derived to mitigate and decrease the occurrence of similar cases.