Extension of platelet shelf life with an improved bacterial testing algorithm

Cutibacterium acnes contamination does not enhance the proinflammatory profile of platelet concentrates

BACKGROUND

Cutibacterium acnes, a common anaerobic platelet concentrate (PC) contaminant, has been associated with rare mild adverse transfusion reactions and is often considered a harmless commensal. Notably, C. acnes can cause chronic infections and has been shown to induce the release of proinflammatory cytokines by immune cells. Since elevated concentrations of proinflammatory factors in PCs have been linked to noninfectious adverse reactions, this study aimed to assess whether C. acnes could elicit the release and accumulation of proinflammatory factors during PC storage, thereby enhancing the risk of such reactions.

STUDY DESIGN/METHODS

Four ABO-matched buffy coat PCs were pooled and split into six units, each were inoculated with either saline (negative control), a Staphylococcus aureus isolate (positive control, 30 colony forming units [CFU]/unit), or four C. acnes PC isolates (10 CFU/mL) and stored at 20-24°C with agitation. Bacterial counts, platelet activation, and concentration of proinflammatory factors were assessed on days 0, 3, and 5. N = 3.

RESULTS

C. acnes counts remained stable, while S. aureus proliferated reaching 108CFU/mL by the end of PC storage. By day 5, no significant differences in platelet activation or proinflammatory cytokine profiles were observed in C. acnes-contaminated PCs compared to the negative control (p > .05), while there was a significant increase (p ≤ .05) in sCD40L concentration (day 3), and platelet activation and IL-8 concentration (day 5) in S. aureus-contaminated units.

DISCUSSION

C. acnes contamination does not promote the accumulation of proinflammatory factors in the absence of proliferation during storage and may not enhance the risk of inflammatory reactions when transfused to patients.

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.

Delayed cold-stored vs. room temperature stored platelet transfusions in bleeding adult cardiac surgery patients-a randomized multicentre pilot study (PLTS-1)

BACKGROUND

Platelets stored at 1-6 °C are hypothesized to be more hemostatically active than standard room temperature platelets (RTP) stored at 20-24 °C. Recent studies suggest converting RTP to cold-stored platelets (Delayed Cold-Stored Platelets, DCSP) may be an important way of extending platelet lifespan and increasing platelet supply while also activating and priming platelets for the treatment of acute bleeding. However, there is little clinical trial data supporting the efficacy and safety of DCSP compared to standard RTP.

METHODS

This protocol details the design of a multicentre, two-arm, parallel-group, randomized, active-control, blinded, internal pilot trial to be conducted at two cardiac surgery centers in Canada. The study will randomize 50 adult (≥ 18 years old) patients undergoing at least moderately complex cardiac surgery with cardiopulmonary bypass and requiring platelet transfusion to receive either RTP as per standard of care (control group) or DCSP (intervention group). Patients randomized to the intervention group will receive ABO-identical, buffy-coat, pathogen-reduced, platelets in platelet additive solution maintained at 22 °C for up to 4 days then placed at 4 °C for a minimum of 24 h, with expiration at 14 days after collection. The duration of the intervention is from the termination of cardiopulmonary bypass to 24 h after, with a maximum of two doses of DCSP. Thereafter, all patients will receive RTP. The aim of this pilot is to assess the feasibility of a future RCT comparing the hemostatic effectiveness of DCSP to RTP (defined as the total number of allogeneic blood products transfused within 24 h after CPB) as well as safety. Specifically, the feasibility objectives of this pilot study are to determine (1) recruitment of ≥ 15% eligible patients per center per month); (2) appropriate platelet product available for ≥ 90% of patients randomized to the cold-stored platelet group; (3) Adherence to randomization assignment (> 90% of patients administered assigned product).

DISCUSSION

DCSP represents a promising logistical solution to address platelet supply shortages and a potentially more efficacious option for the management of active bleeding. No prospective clinical studies on this topic have been conducted. This proposed internal pilot study will assess the feasibility of a larger definitive study.

TRIAL REGISTRATION

NCT06147531 (clinicaltrials.gov).

Chemical and Microbiological Changes of Expired Platelet Concentrate

Background

Platelets are a commonly used blood component to prevent or treat bleeding in patients with thrombocytopenia or platelet dysfunction. They are stored at room temperature (22-24°C) for five days unless specific measures are taken to extend the shelf life to seven days or more. After five days, this study evaluated platelet units' biochemical changes and bacterial growth.

Study Design and Methods

Platelet concentrate was collected from 30 random donors: 8 females and 22 males. The collected samples were then placed on an agitator at room temperature and tested for their pH, protein content, and glucose levels using Roche Combur 100 Test® Strips. The Haemonetics eBDS™ System was used for bacterial detection. The measurements were taken on day five as the control and then repeated on days 7, 9, and 11 to observe any changes. On days 5 and 7, all parameters remained unchanged. However, glucose levels significantly changed (p=<0.0001) on days 9 and 11. Regarding pH, a significant change was observed on day 9 (p=0.033) and day 11 (p=0.0002).

Results

There were no significant changes in all parameters on days 5 and 7. However, glucose was substantially changed (p=<0.0001) on days 9 and 11. For pH, there was a significant change in pH on day 9 (p=0.033) and day 11 (p=0.0002).

Discussions

Our study found that platelet concentrate extension is possible for up to seven days. However, further studies are needed to evaluate platelet function during expiry time and to assess the stability of platelet morphology and function.

Comparable bacterial growth in platelet concentrates suspended in plasma and platelet additive solution and improved detection of bacterial contamination using a new generation automated culture system

BACKGROUND

Microbial screening of platelet concentrates (PC) with automated culture methods is widely implemented to reduce septic transfusion reactions. Herein, detection of bacterial contamination in PC was compared between units prepared in plasma and a mix of plasma and platelet additive solution (PAS) and between the BACT/ALERT 3D and next generation BACT/ALERT VIRTUO systems.

STUDY DESIGN/METHODS

Double apheresis units were split into single units, diluted in either PAS (PAS-PC) or plasma (plasma-PC), and tested for in vitro quality and sterility prior to spiking with ~30 CFU/unit of Staphylococcus epidermidis, Staphylococcus aureus, Serratia marcescens, and Klebsiella pneumoniae or ~10 CFU/mL of Cutibacterium acnes. Spiked PC were sampled for BACT/ALERT testing (36 and 48 h post-spiking) and colony counts (24, 36, and 48 h post-spiking). Times to detection (TtoD) and bacterial loads were compared between PC products and BACT/ALERT systems (N = 3).

RESULTS

Bacterial growth was similar in plasma-PC and PAS-PC. No significant differences in TtoD were observed between plasma-PC and PAS-PC at the 36-h sampling time except for S. epidermidis which grew faster in plasma-PC and C. acnes which was detected earlier in PAS-PC (p < .05). Detection of facultative bacteria was 1.3-2.2 h sooner in VIRTUO compared with 3D (p < .05) while TtoD for C. acnes was not significantly different between the two systems.

DISCUSSION

Comparable bacterial detection was observed in plasma-PC and PAS-PC with PC sampling performed at 36-h post blood collection. PC sampling at ≤36 h could result in faster detection of facultative pathogenic organisms with the VIRTUO system and improved PC safety.

Sebum Components Dampen the Efficacy of Skin Disinfectants against Cutibacterium acnes Biofilms

At Canadian Blood Services, despite the use of 2% chlorhexidine and 70% isopropyl alcohol (standard disinfectant, SD) prior to venipuncture, Cutibacterium acnes evades eradication and is a major contaminant of platelet concentrates (PCs). Since C. acnes forms bacterial aggregates known as biofilms in the sebaceous niches of the skin, this study aimed to assess whether sebum-like components impact disinfectant efficacy against C. acnes leading to its dominance as a PC contaminant. C. acnes mono-species and dual-species biofilms (C. acness and a transfusion-relevant Staphylococcus aureus isolate) were formed in the presence and absence of sebum-like components and exposed to SD, a hypochlorous acid-based disinfectant (Clinisept+, CP), or a combination of both disinfectants to assess disinfectant efficacy. Our data indicate that sebum-like components significantly reduce the disinfectant efficacy of all disinfectant strategies tested against C. acnes in both biofilm models. Furthermore, though none of the disinfectants led to bacterial eradication, the susceptibility of C. acnes to disinfectants was heightened in an isolate-dependent manner when grown in the presence of S. aureus. The reduction of skin disinfection efficacy in the presence of sebum may contribute to the overrepresentation of C. acnes as a PC contaminant and highlights the need for improved disinfection strategies.

Changing Strategies for the Detection of Bacteria in Platelet Components in Ireland: From Primary and Secondary Culture (2010-2020) to Large Volume Delayed Sampling (2020-2023)

Bacterial contamination of platelet components (PC) poses the greatest microbial risk to recipients, as bacteria can multiply over the course of PC storage at room temperature. Between 2010 and 2020, the Irish Blood Transfusion Service (IBTS) screened over 170,000 buffy coat-derived pooled (BCDP) and single-donor apheresis platelets (SDAPs) with the BACT/ALERT 3D microbial detection system (Biomerieux, L'Etoile, France), using a two-step screening protocol which incorporated primary and secondary cultures. Although the protocol was successful in averting septic transfusion reactions (STRs), testing large sample volumes at later time points was reported to improve detection of bacterial contamination. A modified large-volume delayed sampling (LVDS)-type protocol was adopted in 2020, which in the case of SDAP was applied to collections rather than individual splits (2020-2023, 44,642 PC screened). Rates of bacterial contamination for BCDP were 0.125% on Day-2, 0.043% on Day-4 vs. 0.191% in the post-LVDS period. SDAP contamination rates in the pre-LVDS period were 0.065% on Day-1, 0.017% on Day-4 vs. 0.072% in the post-LVDS period. Confirmed STRs were absent, and the interdiction rate for possibly contaminated SDAP was over 70%. In the post-LVDS period, BCDPs had a higher total positivity rate than SDAPs, 0.191% (1:525) versus 0.072% (1:1385), respectively, (chi-squared 12.124, 1 df, p = 0.0005). The majority of organisms detected were skin-flora-type, low pathogenicity organisms, including coagulase-negative staphylococci and Cutibacterium acnes, with little change in the frequency of clinically significant organisms identified over time. Both protocols prevented the issue of potentially harmful components contaminated (rarely) with a range of pathogenic bacteria, including Escherichia coli, Serratia marcesens, Staphylococcus aureus, and streptococci. Culture positivity of outdates post-LVDS whereby 100% of expired platelets are retested provides a residual risk estimate of 0.06% (95% CI 0.016-0.150). However, bacterial contamination rates in expired platelets did not demonstrate a statistically significant difference between the pre-LVDS 0.100% (CI 0.033-0.234) and post-LVDS 0.059% (0.016-0.150) periods (chi-squared = 0.651, 1 df, p = 0.42).

Nutrient supplementation of culture media improves the detection of Cutibacterium acnes in platelet components by an automated culture system

BACKGROUND AND OBJECTIVES

Platelet concentrates (PCs) contaminated with Cutibacterium acnes are often transfused prior to detection by the BACT/ALERT system. Though C. acnes is implicated in mild transfusion reactions, delayed clinical effects are unknown. This study assessed the ability to enhance C. acnes detection by supplementing culture media with Tween 80 (T80, an oleic acid source) and a commercial nutrient supplement.

MATERIALS AND METHODS

Anaerobic culture bottles (BPN) were supplemented with T80 or oleic acid. T80-supplemented BPN bottles were inoculated with four C. acnes isolates (10 or 100 colony-forming units [CFU]/bottle) or other transfusion-relevant bacteria (10 CFU/bottle). Samples of plasma containing SSP+ (platelet additive solution [PAS]) (PAS-plasma) at different concentrations, plasma-PCs and PAS-PCs, spiked with two C. acnes isolates (10 CFU/bottle), were inoculated into T80-supplemented BPN bottles. Furthermore, plasma-PCs were spiked with C. acnes and tested in BPN bottles supplemented with the BD Difco Supplement VX (BDVx). Bottles were incubated in the BACT/ALERT system and times to detection (TtoD) were compared (N = 3).

RESULTS

A reduction in TtoD of ≤3.5 days was observed for C. acnes in T80-supplemented BPN, while other species did not show the same effect. However, false positives were observed when T80-supplemented BPN was inoculated with PAS-plasma (except for 70% PAS:30% plasma), plasma-PCs or PAS-PCs. Oleic acid supplementation also resulted in false positives. Interestingly, BDVx-supplemented BPN reduced the TtoD of C. acnes in PCs by ≤1.2 days (p < 0.05), with no false-positive results.

CONCLUSION

BDVx supplementation for detection of C. acnes from PCs could result in timely unit retrieval, preventing the transfusion of contaminated products. In clinical settings, T80 supplementation could significantly enhance C. acnes detection from non-blood-derived samples.

Cold-stored platelets for acute bleeding in cardiac surgical patients: a narrative review

PURPOSE

Cold-stored platelets (CSP) are an increasingly active topic of international research. They are maintained at 1-6 °C, in contrast to standard room-temperature platelets (RTP) kept at 20-24 °C. Recent evidence suggests that CSP have superior hemostatic properties compared with RTP. This narrative review explores the application of CSP in adult cardiac surgery, summarizes the preclinical and clinical evidence for their use, and highlights recent research.

SOURCE

A targeted search of MEDLINE and other databases up to 24 February 2022 was conducted. Search terms combined concepts such as cardiac surgery, blood, platelet, and cold-stored. Searches of trial registries ClinicalTrials.gov and WHO International Clinical Trials Registry Platform were included. Articles were included if they described adult surgical patients as their population of interest and an association between CSP and clinical outcomes. References of included articles were hand searched.

PRINCIPAL FINDINGS

When platelets are stored at 1-6 °C, their metabolic rate is slowed, preserving hemostatic function for increased storage duration. Cold-stored platelets have superior adhesion characteristics under physiologic shear conditions, and similar or superior aggregation responses to physiologic agonists. Cold-stored platelets undergo structural, metabolic, and molecular changes which appear to "prime" them for hemostatic activity. While preliminary, clinical evidence supports the conduct of trials comparing CSP with RTP for patients with platelet-related bleeding, such as those undergoing cardiac surgery.

CONCLUSION

Cold-stored platelets may have several advantages over RTP, including increased hemostatic capacity, extended shelf-life, and reduced risk of bacterial contamination. Large clinical trials are needed to establish their potential role in the treatment of acutely bleeding patients.

Safety Analysis of Extended Platelet Shelf-Life with Large-Volume Delayed Sampling on BACT/ALERT® VIRTUO® in Australia

Transfusion-transmitted bacterial infection (TTBI) is the leading cause of transfusion-transmitted infections. Platelet components are more likely to be associated with bacterial contamination due to their storage requirements. Australian Red Cross Lifeblood introduced the bacterial contamination screening (BCS) of all platelet components in 2008. The process was recently updated with the use of BACT/ALERT® VIRTUO®, a large-volume delayed sampling (LVDS) protocol and extending platelet shelf-life to seven days. This article describes the results from the routine BCS of platelet components in Australia. Use of VIRTUO has resulted in lower false-positive rates, reducing wastage and improving platelet inventory. Our findings show that the combination of LVDS and VIRTUO improves the safety of platelet transfusions through earlier time to detection, especially for pathogenic bacterial species. Pathogenic bacteria grew within 24 h of incubation with a clear delineation between pathogenic and non-pathogenic species. The data show this protocol is very safe, with no TTBI cases during this time. There were no TTBI reports in recipients of platelet components that subsequently had a positive culture with Cutibacterium species, probably due to the low pathogenic potential of these organisms and slow replication in aerobic platelet bags. We conclude there is no advantage in incubating culture bottles beyond five days.

A multiphasic approach to solve misidentification of Cutibacterium acnes as Atopobium vaginae during routine bacterial screening of platelet concentrates using the VITEK 2 system

Skin flora bacteria, such as Cutibacterium acnes , are the predominant contaminants of blood products used for transfusion. Platelet concentrates (PCs), a therapeutic product used to treat patients with platelet deficiencies, are stored at ambient temperature under agitation, providing ideal conditions for bacterial proliferation. At Canadian Blood Services, PCs are screened for microbial contamination using the automated BACT/ALERT culture system. Positive cultures are processed and contaminating organisms are identified using the VITEK 2 system. Over a period of approximately 2 years, several PC isolates were identified as Atopobium vaginae to a high level of confidence. However, since A. vaginae is associated with bacterial vaginosis and is not a common PC contaminant, a retrospective investigation revealed that in all cases C. acnes was misidentified as A. vaginae . Our investigation demonstrated that the media type used to grow PC bacterial isolates can have a significant impact on the results obtained on the VITEK 2 system. Furthermore, other identification methods such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALD-TOF MS) and PCR amplification of the 16S RNA gene were only partially successful in the identification of C. acnes . Therefore, our findings support a multiphasic approach when PC isolates are identified as A. vaginae by the VITEK 2 system for proper identification of C. acnes using macroscopic, microscopic and other biochemical analyses.

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.

Staphylococcal Enterotoxins Enhance Biofilm Formation by Staphylococcus aureus in Platelet Concentrates

Biofilm formation and slow growth by Staphylococcus aureus in platelet concentrates (PCs) cause missed detection of this bacterium during routine PC screening with automated culture systems. This heightens the chances of false-negative screening transfusions and pre-disposes transfusion patients to an elevated risk of sepsis due to secretion of staphylococcal enterotoxins (SEs) in PCs. A hybrid approach of comparative RNAseq analyses and CRISPR mutagenesis of SE genes was employed to investigate the effect of SEs in S. aureus growth and biofilm formation in PCs. RNAseq data showed no differential expression for key biofilm genes, whereas SE genes were upregulated (>0.5- to 3.6-fold change) in PCs compared to trypticase soy broth (TSB). Remarkably, growth and biofilm formation assays revealed increased growth for the S. aureus SE mutants, while their ability to form biofilms was significantly impaired (−6.8- to −2.4-fold change) in comparison to the wild type strain, in both PCs and TSB. Through the well-established superantigen mechanism of SEs, we propose three roles for SEs during biofilm development in PCs: (1) provide a scaffold for biofilm matrix, (2) mediate cell-to-cell aggregation, and (3) guarantee biofilm survival. Furthermore, SE contribution to both growth and biofilm development seems to be centrally regulated by agr via quorum sensing and by saeSR and sigB. This study reveals new roles for SEs, which enforce their relevance in ensuring PC safety for transfusion patients. It further deciphers the underlying reasons for failed S. aureus detection in PCs during screening with automated culture systems.

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.

Current Status of and Global Trends in Platelet Transfusion Refractoriness From 2004 to 2021: A Bibliometric Analysis

Platelet transfusion refractoriness (PTR) is common in patients with hematology and oncology and is becoming an important barrier in the treatment of thrombocytopenia and hemorrhage. Bibliometrics is an effective method for identifying existing research achievements, important breakthroughs, current research hotspots, and future development trends in any given field. In recent years, research on PTR has received increasing attention, but a bibliometric analysis of this field has not yet been reported. In this study, we applied bibliometrics to analyze the existing literature on PTR research over the past 17 years. On November 1, 2021, we began a publications analysis of PTR research using the Science Citation Index Expanded of the Web of Science Core Collection with collection dates from 2004 to 2021. This research aimed to summarize the state of PTR research using Bibliometrix to identify connections between different elements (i.e., authors, institutions, countries, journals, references, and keywords) using VOS viewer analyses to visualize key topics and trends in PTR research using Cite Space and gCLUTO. The results of all 310 studies showed that the annual number of publications focused on PTR is steadily increasing, with the United States of America and Japan making significant contributions. We noted that the research group led by Dr. Sherrill J. Slichter was prominent in this field, while Estcourt Lise may become the most influential newcomer. Transfusion was the most popular journal, and Blood was the most cited journal. Using various analyses, including co-cited analysis, historiography analysis, citation burst analysis, and factorial analysis, we pointed out and discussed contributing publications. According to occurrence analysis, co-word biclustering analysis, landform map, thematic evolution, and thematic map, we believe that “activation,” “p-selection,” “CD36 deficiency,” “gene-frequencies,” “CD109,” “HPA-1,” and “beta (3) integrin” may become new trends in PTR research. The outcome of our bibliometric analyses has, for the first time, revealed profound insights into the current state and trends in PTR research. The systematic analysis provided by our study clearly demonstrates the field's significant advancements to all researchers who are interested in a quick and comprehensive introduction to the field.

Current status of rapid bacterial detection methods for platelet components: A 20-year review by the ISBT Transfusion-Transmitted Infectious Diseases Working Party Subgroup on Bacteria

BACKGROUND AND OBJECTIVES

Bacterial contamination of platelet components (PCs) poses a safety challenge for transfusion patients. Despite mitigation interventions, the residual risk of transfusion-transmitted bacterial infections remains predominant. PC safety can be improved either by pathogen reduction or by implementation of bacterial detection methods. Detection methodologies include culture methods and rapid detection methods. The current review focuses on currently available rapid detection methods.

MATERIALS AND METHODS

We reviewed published manuscripts since 2000 on rapid bacterial detection methods used for PC screening with result determination within 4 h. Methods meeting this criterion included Verax PGDprime, BacTx and nucleic amplification testing. The analytical and diagnostic sensitivity and specificity of these systems were assessed.

RESULTS

The analytical sensitivity between the different detection methods ranged between 50 and 100,000 CFU/ml. The sample volume used by these testing systems varies between 0.5 and 1.0 ml of PCs. A delay of at least 48 h before sampling enhances detectability. All rapid detection methods generate results in a timely manner, allowing testing to be performed before transfusion with optimal sensitivity.

CONCLUSION

Rapid detection methods improve PC safety regarding bacterial contamination. The assays are optimal for rapidly growing bacteria, which are more likely to cause septic transfusion reactions in patients. Because of the reduced diagnostic sensitivity, the sample collection should be late in shelf-life and ideally just before transfusion. The major benefit of these methods is that the test result can be obtained before releasing PCs for transfusion or to be used in combination with other screening methods applied early during PC storage.

The international experience of bacterial screen testing of platelet components with automated microbial detection systems: An update

In 2014, the bacterial subgroup of the Transfusion-Transmitted Infectious Diseases working party of ISBT published a review on the International Experience of Bacterial Screen Testing of Platelet Components (PCs) with an Automated Microbial Detection System. The purpose of this review, which is focused on publications on or after 2014, is to summarize recent experiences related to bacterial contamination of PCs and the use of an automated culture method to safeguard the blood supply. We first reviewed septic transfusion reactions after PC transfusion as reported in national haemovigilance systems along with a few reports from various countries on bacterial contamination of blood products. Next, we reviewed PC automated culture protocols employed by national blood services in the United Kingdom, Australia, Canada and large blood collection organization and hospital transfusion services in the United States. Then, we acknowledged the limitations of currently available culture methodologies in abating the risks of transfusion-transmitted bacterial infection, through a review of case reports. This review was neither meant to be critical of the literature reviewed nor meant to identify or recommend a best practice. We concluded that significant risk reduction can be achieved by one or a combination of more than one strategy. No one approach is feasible for all institutions worldwide. In selecting strategies, institutions should consider the possible impact on platelet components availability and entertain a risk-based decision-making approach that accounts for operational, logistical and financial factors.

Complete Genome Sequence of Staphylococcus aureus PS/BAC/169/17/W, Isolated from a Contaminated Platelet Concentrate in England

We report the genome sequence of Staphylococcus aureus PS/BAC/169/17/W, which was isolated in 2017 from a contaminated platelet concentrate at the National Health Service Blood and Transplant. Assessment of the genome sequence of this strain showed the presence of a 2,753,746-bp chromosome and a plasmid of 2,762 bp.

Complete Genome Sequence of Staphylococcus aureus CI/BAC/25/13/W, Isolated from Contaminated Platelet Concentrates in England

We present the genome sequence of Staphylococcus aureus CI/BAC/25/13/W, which was isolated in 2013 as a contaminant of a platelet concentrate with abnormal clotting at the National Health Service Blood and Transplant. Assessment of the genome sequence showed the presence of one chromosome (2,719,347 bp) and one plasmid (1,533 bp).

Comprehensive Study Identifies a Sensitive, Low-Risk, Closed-System Model for Detection of Fungal Contaminants in Cell and Gene Therapy Products

The U.S. Food and Drug Administration (FDA) regulates manufacturing and testing of advanced therapeutic medicinal products (ATMPs) to ensure the safety of each product for human use. Gold-standard sterility testing (USP<71>) and alternative blood culture systems have major limitations for the detection of fungal contaminants. In this study, we evaluated the performance of iLYM (lactic acid-fermenting organisms, yeasts, and mold) medium (designed originally for the food and beverage industry) to assess its potential for use in the biopharmaceutical field for ATMP sterility testing. We conducted a parallel evaluation of four different test systems (USP<71>, BacT/Alert, Bactec, and Sabouraud dextrose agar [SDA] culture), three different bottle media formulations (iLYM, iFA Plus, and Myco/F Lytic), and two incubation temperatures (22.5°C and 32.5 to 35°C) using a diverse set of fungi (n = 51) isolated from NIH cleanroom environments and previous product contaminants. Additionally, we evaluated the effect of agitation versus delayed-entry static preincubation on test sensitivity and time to detection (TTD). Overall, delayed entry of bottles onto the BacT/Alert or Bactec instruments (with agitation) did not improve test performance. USP<71> and SDA culture continued to significantly outperform each automated culture condition alone. However, we show, for the first time, that a closed-system, dual-bottle combination of iLYM 22.5°C and iFA Plus 32.5°C can provide high fungal sensitivity, statistically comparable to USP<71>, when tested against a diverse range of environmental fungi. Our study fills a much-needed gap in biopharmaceutical testing and offers a favorable testing algorithm that maximizes bacterial and fungal test sensitivity while minimizing risk of product contamination associated with laboratory handling.

Clinical and economic impacts of large volume delayed sampling and pathogen reduction technology platelet processing strategies in the United States

BACKGROUND

Large volume delayed sampling (LVDS) and pathogen reduction technology (PRT) are strategies for platelet processing to minimize transfusion of contaminated platelet components (PCs). This study holistically compares the economic and clinical impact of LVDS and PRT in the United States.

STUDY DESIGN AND METHODS

A decision model was constructed to simulate collection, processing, and use of PCs and to compare processing strategies: PRT with 5-day shelf life, LVDS with 7-day shelf life (LVDS7), and LVDS with 5-day shelf life extended to 7 days with secondary testing (LVDS5/2). Target population was adults requiring two or more transfusions. Collection, processing, storage, and distribution data were obtained from the National Blood Collection and Utilization Survey and published literature. Patient outcomes associated with transfusions were obtained from AABB guidelines, meta-analyses, and other published clinical studies. Costs were obtained from reimbursement schedules and other published sources.

RESULTS

Given 10,000 donated units, 9512, 9511, and 9651 units of PRT, LVDS5/2, and LVDS7 PCs were available for transfusion, respectively. With these units, 1502, 2172, and 2329 transfusions can be performed with similar levels of adverse events. Assuming 30 transfusions a day, a hospital would require 69,325, 47,940, and 45,383 units of PRT, LVDS5/2, and LVDS7 platelets to perform these transfusions. The mean costs to perform transfusions were significantly higher with PRT units.

CONCLUSIONS

Compared with PRT, LVDS strategies were associated with lower costs and higher PC availability while patients experienced similar levels of adverse events. Increased utilization of LVDS has the potential to improve efficiency, expand patient access to platelets, and reduce health care costs.

A survey of US hospitals on platelet inventory management, transfusion practice, and platelet availability

BACKGROUND

A survey of US hospitals was conducted to increase our understanding of the current state of platelet (PLT) practice and supply. The survey captures information on transfusion practice and inventory management, including stock levels, outdate rates, ability to return or transfer PLTs, and low dose PLTs. Notably, the survey also elucidates PLT availability challenges and impact to patient care.

STUDY DESIGN AND METHODS

A 27 question online survey was distributed directly to over 995 US hospitals and indirectly through blood centers to many more between September 27 and October 25, 2019. Descriptive statistics were used for respondent characteristics. Bivariate analysis was performed and correlation coefficients, chi square tests, and p values determined statistical significance of relationships between variables.

RESULTS

Four hundred and eighty-one hospitals completed the survey of which 21.6%, 53.2%, and 25.2% were characterized as small, medium, and large hospitals, respectively. Some key observations from this survey include: (1) there is an opportunity for greater adherence to evidence-based guidelines; (2) higher outdate rates occur in hospitals stocking less than five PLTs and the ability to return or transfer PLTs lowers outdates; (3) use of low dose apheresis PLTs varies; and (4) decreased PLT availability is commonly reported, especially in hospitals with high usage, and can lead to delays in transfusions or surgeries.

CONCLUSION

This survey represents a comprehensive national assessment of inventory management practices and PLT availability challenges in US hospitals. Findings from this survey can be used to guide further research, help shape future guidance for industry, and assist with policy decisions.