Platelet safety strategies in Japan: impact of short shelf life on the incidence of septic reactions

Evaluation of bacterial safety approaches of platelet blood concentrates: bacterial screening and pathogen reduction

This mini-review analyzed two approaches to screening bacterial contamination and utilizing pathogen reduction technology (PRT) for Platelet concentrates (PCs). While the culture-based method is still considered the gold standard for detecting bacterial contamination in PCs, efforts in the past two decades to minimize transfusion-transmitted bacterial infections (TTBIs) have been insufficient to eliminate this infectious threat. PRTs have emerged as a crucial tool to enhance safety and mitigate these risks. The evidence suggests that the screening strategy for bacterial contamination is more successful in ensuring PC quality, decreasing the necessity for frequent transfusions, and improving resistance to platelet transfusion. Alternatively, the PRT approach is superior regarding PC safety. However, both methods are equally effective in managing bleeding. In conclusion, PRT can become a more prevalent means of safety for PCs compared to culture-based approaches and will soon comprehensively surpass culture-based bacterial contamination detection methods.

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.

Dual-Temperature Microbiological Control of Cellular Products: A Potential Impact for Bacterial Screening of Platelet Concentrates?

An experimental study by the Paul-Ehrlich Institute (PEI) demonstrated that temperatures between 35 and 37 °C are too high for the growth of some bacterial strains (e.g., Pseudomonas fluorescens), leading to false negative results. Thus, the question of whether it is necessary to adapt incubation temperatures for the microbiological control of blood products, especially platelet concentrates (PCs), to enhance safety and regulatory compliance has arisen. In order to further elucidate this issue, the growth capability of different bacterial strains of interest in PCs and the detection efficacy of cultivation of these at different incubation temperatures must be taken into account. Therefore, we inoculated PCs with 46 different strains (3-6 PCs from different donors per strain) from different origins (PC isolates, reference strains) and stored PCs at 20-22 °C under constant agitation. On day three of storage, the inoculated PCs were sampled; aerobic and anaerobic culture bottles (BacT/Alert AST/NST) were each inoculated with 5 mL of sample, and culture bottles were incubated at 25 and 35 °C using the automated BacT/Alert Dual-temperature system. Bacterial proliferation was enumerated using a colony-forming assay. All strains of Enterobacteriacae (n = 5), Staphy-lococcus spp. (n = 11), Streptococcus spp. (n = 5), and Bacillus spp. (n = 4) and most Pseudomonas aeruginosa strains (4 of 5) tested showed the capability to grow in most inoculated PCs, revealing a faster time to detection (TTD) at an incubation temperature of 35 °C. The tested Pseudomonas putida (n = 3) strains showed a noticeably reduced capability to grow in PCs. Nonetheless, those with a notable growth capability revealed a faster TTD at an incubation temperature of 35 °C. Only one of the four Pseudomonas fluorescens strains tested (strain ATCC 13525) was able to grow in PCs, showing a faster TTD at an incubation temperature of 25 °C but also detection at 35 °C. The commonly detected bacteria involved in the bacterial contamination of PCs showed a superior TTD at 35 °C incubation. Only one P. fluorescens strain showed superior growth at 25 °C; however, the microbiological control at 35 °C did not fail to identify this contamination. In conclusion, the use of PC screening using a dual-temperature setting for microbiological control is presently not justified according to the observed kinetics.

An evaluation of the clinical impacts of 7-day platelets

BACKGROUND

In August 2017, Canadian Blood Services extended the shelf-life of platelet concentrates from 5 to 7 days. The clinical impacts of this policy change remain unclear.

STUDY DESIGN AND METHODS

We used a before-after retrospective design of platelet-transfused adult inpatients in Hamilton, ON, Canada. Data were captured for 18 months before (Period 1: February 2016-July 2017) and 18 months after (Period 2: September 2017-February 2019) 7-day platelet implementation. Primary outcome was absolute platelet count increment (ACI) in univariate and multivariate analyses adjusted for confounders. Data were obtained from our institution's transfusion database, Ontario's Transfusion Transmitted Injuries Surveillance System, and the blood supplier.

RESULTS

Overall, 1360 patients with single dose platelet transfusions were included in Period 1 and 1211 patients in Period 2. Median age at admission was 66 years, and approximately 40% of patients underwent cardiac surgery. Using a non-inferiority margin of -10 × 10⁹ /L, platelets transfused during the 7-day storage period were non-inferior to those transfused in the 5-day storage period [mean count difference - 4.63 × 10⁹ /L (95% CI -7.40 to -1.87, p = 0.0001)]. However, platelet ACIs following transfusion consistently trended lower in the 7-day group for all patients and subgroups. No differences in secondary clinical outcomes were observed. Platelet expiry reduced from 8.1 to 6.3% (p < 0.0001).

CONCLUSION

Platelet transfusions following 7-day storage policy were non-inferior to transfusions in the 5-day policy period, although reduced ACIs were observed. There were no increases in adverse clinical outcomes.

Hemostatic function of cold-stored platelets in a thrombocytopenic rabbit bleeding model

BACKGROUND

Transfusion of cold-stored platelet concentrates (CS-PCs) appears effective in massively bleeding patients. However, few studies have evaluated their in vivo hemostatic function in severe thrombocytopenia.

STUDY DESIGN AND METHODS

The in vivo function of plasma-depleted human PCs was evaluated in rabbits with a blocked reticuloendothelial system and busulfan-induced thrombocytopenia. On day 1, a human apheresis PC was processed in a platelet additive solution (PAS-PC) and split evenly for cold or room temperature storage (RTS). On days 3, 6, or 9, RTS- or CS-PAS-PCs were transfused (4.0 × 10⁹ platelets/kg) after plasma depletion into two to four rabbits that developed adequate thrombocytopenia (<25 × 10⁹ /L). Ear bleeding time was measured by two incisions in small veins. The hemostatic rate was defined as the percentage of rabbits achieving bleeding cessation within 600 s at either incision. The experiment was repeated using five different PCs on each storage day.

RESULTS

The mean pre-transfusion rabbit platelet count was 8.6 ± 5.2 × 10⁹ /L. The hemostatic rates with RTS- and CS-PAS-PCs were both 100% on day 3, 93 ± 15% and 73 ± 15% on day 6 (p = .07), and 65 ± 36% and 73 ± 37% on day 9 (p = .27), respectively, with no statistical differences. Total platelet counts were significantly lower after CS-PAS-PC than RTS-PAS-PC transfusion on all days (e.g., 58.7 ± 5.7 vs. 42.4 ± 14.7 × 10⁹ /L, p = .0007, day 9), and did not reach 50 × 10⁹ /L in several experiments. Platelet count increments correlated significantly with hemostatic efficacy for CS-PAS-PC transfusion only.

DISCUSSION

CS-PAS-PCs might achieve similar hemostasis as RTS-PAS-PCs in thrombocytopenic patients with mild bleeding. Hemostatic efficacy could be improved by transfusing more CS-PAS-PCs.

Adverse transfusion reactions and what we can do

INTRODUCTION

Transfusions of blood and blood components have inherent risks and the ensuing adverse reactions. It is very important to understand the adverse reactions of blood transfusion comprehensively for ensuring the safety of any future transfusions.

AREAS COVERED

According to the time of onset, adverse reactions of blood transfusion are divided into immediate and delayed transfusion reactions. In acute transfusion reactions, timely identification and immediate cessation of transfusion is critical. Vigilance is required to distinguish delayed responses or reactions that present non-specific signs and symptoms. In this review, we present the progress of mechanism, clinical characteristics and management of commonly encountered transfusion reactions.

EXPERT OPINION

The incidence of many transfusion-related adverse events is decreasing, but threats to transfusion safety are always emerging. It is particularly important for clinicians and blood transfusion staff to recognize the causes, symptoms and treatment methods of adverse blood transfusion reactions to improve the safety. In the future, at-risk patients will be better identified and can benefit from more closely matched blood components.

Characteristics of False-Positive Alarms in the BacT/Alert 3D System

The BacT/Alert system has been used for detecting the presence of bacteria in various clinical settings as well as in blood services, but it is associated with a relatively high incidence of false-positive results. We analyzed the results of our quality control sterility testing of blood products by BacT/Alert 3D to understand the mechanism of false-positive results. Anaerobic and aerobic bottles were inoculated with 10 mL of samples and cultured in BacT/Alert 3D for 10 days. Positive-reaction cases were classified as true positive if any bacterium was identified or false positive if the identification test had a negative result. The detection algorithm and the bottle graph pattern of the positive reaction cases were investigated. Among the 43,374 samples, 25 true positives (0.06%) and 29 false positives (0.07%) were observed. Although the detection algorithm of all true positives and 25 of 29 false positives was accelerating production of CO2, a steep rise in the bottle graph was observed only in the true positives, and it was not observed in either of the false positives. Four of 29 false positives were dependent on high baseline scatter reflections. Furthermore, evaluating the bottle graph pattern of Streptococcus pneumoniae, a bacterium known to autolyze, we confirmed that no viable bacterium was detected even if a steep rise was observed. In conclusion, the bottle graph pattern of positive reactions allows the differentiation between true positives and false positives. In case of a steep rise without bacterium detection, the bacterium might have autolyzed. Moreover, positive reactions with high baseline scatter reflections, despite immediate loading of bottles after sampling, are potentially false positive. IMPORTANCE In clinical settings, false-positive results are treated as positive until bacterial identification. It may result in the discarding of blood products in blood centers or affect clinical decisions in hospitals or testing facilities. Moreover, the management of these samples is usually time- and labor-consuming. The results of our study may help clinicians and laboratory staff in making a more precise evaluation of positive reactions in BacT/Alert.

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

BACKGROUND

Bacterial contamination in platelet concentrates (PCs) is a major problem in transfusion medicine. Contamination with Staphylococcus aureus is occasionally missed, even with cultural screening.

STUDY DESIGN AND METHODS

Donors implicated in S. aureus-contaminated PC were followed up. Skin and nasal swab specimens from six donors and S. aureus isolated from PCs related to these donors were subjected to multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) to determine the identity of bacteria. To evaluate the validity of the screening method using BacT/ALERT 3D, we spiked S. aureus and three other bacterial species as comparisons into PCs and investigated their growth pattern.

RESULTS

S. aureus was isolated from all nasal specimens and from the arm skin specimens of three donors with atopic dermatitis. In all cases, the S. aureus strains isolated from the PC and those from the nasal and skin specimens of the same donor showed concordant results using MLST and PFGE. In the spiking study, S. aureus showed irregular detectability over 24 to 48 h post-spike periods, whereas the three other bacterial species were detected in all culture bottles after a 24-h post-spike period.

DISCUSSION

The strain identity of S. aureus between donor and PC suggests that the contaminants were derived from those colonized in the donor. Furthermore, S. aureus yielded false-negative results using BacT/ALERT 3D.

Current challenges in platelet transfusion

The supply of platelets for transfusion is a logistical challenge due to the physiology of platelets and current measures of transfusion performance dictating storage at 22°C and a short product shelf-life (<7 days). Demand for platelets has increased in recent years and changes in the demographics of the population may enhance this further. Many studies have been conducted to understand what the optimal dose and trigger for transfusion should be, mainly in hematology patients who are the largest cohort that receive platelets, mostly to prevent bleeding. Emerging data suggests that for bleeding patients, where immediate hemostasis is a key consideration, the current standard product may not be optimal. Alternative platelet preparation methods/storage options that may improve the hemostatic properties of platelets are under active development. In parallel with research into alternative platelet products that might enhance hemostasis, better measures for assessing bleeding risk and platelet efficacy are needed.

UV light-emitting diode (UV-LED) at 265 nm as a potential light source for disinfecting human platelet concentrates

The risk of sepsis through bacterial transmission is one of the most serious problems in platelet transfusion. In processing platelet concentrates (PCs), several methods have been put into practice to minimize the risk of bacterial transmission, such as stringent monitoring by cultivation assays and inactivation treatment by photoirradiation with or without chemical agents. As another potential option, we applied a light-emitting diode (LED) with a peak emission wavelength of 265 nm, which has been shown to be effective for water, to disinfect PCs. In a bench-scale UV-LED exposure setup, a 10-min irradiation, corresponding to an average fluence of 9.2 mJ/cm2, resulted in >2.0 log, 1.0 log, and 0.6 log inactivation (mean, n = 6) of Escherichia coli, Staphylococcus aureus, and Bacillus cereus, respectively, in non-diluted plasma PCs. After a 30-min exposure, platelet counts decreased slightly (18 ± 7%: mean ± SD, n = 7); however, platelet surface expressions of CD42b, CD61, CD62P, and PAC-1 binding did not change significantly (P>0.005), and agonist-induced aggregation and adhesion/aggregation under flow conditions were well maintained. Our findings indicated that the 265 nm UV-LED has high potential as a novel disinfection method to ensure the microbial safety of platelet transfusion.