Bacterial sepsis secondary to platelet transfusion: an adverse effect of extended storage at room temperature

Pathogen inactivation of platelets for transfusion

Bacterial contamination of blood components is a recurrent topic in transfusion medicine community. This issue is even more important with platelet transfusions because of storage of platelet components at room temperature for 5 days. Pathogen inactivation methods are a proactive approach to deal with an infectious agent. All available methods use UV light, with or without a photosensitizer, to inactivate potential pathogens. As with other medical interventions, pathogen inactivation methods carry benefits and risks. Among benefits, inactivation of known and unknown transfusion-transmitted pathogens, inactivation of residual leukocytes, and increased storage length from 5 to 7 days are the most interesting. The main risk is the impact on clinical efficacy of pathogen-reduced platelets. After inactivation, pathogen-reduced platelets are associated with a lower number of platelets in the final product, lower 24-hour corrected count increment, and shorter transfusion interval when compared with non-inactivated platelets. However, eight of nine randomized controlled trials showed that transfusing pathogen-reduced platelets were not inferior to transfusing usual platelet components in the prevention of bleeding episodes. In conclusion, in our opinion, increasing safety of platelet transfusions with pathogen inactivation methods is worthy, even the trade-off of causing damage to platelets.

Financial analysis of large-volume delayed sampling to reduce bacterial contamination of platelets

BACKGROUND

Effective and financially viable mitigation approaches are needed to reduce bacterial contamination of platelets in the US. Expected costs of large-volume delayed sampling (LVDS), which would be performed by a blood center prior to shipment to a hospital, were compared to those of pathogen reduction (PR), point-of-release testing (PORt), and secondary bacterial culture (SBC).

METHODS

Using a Markov-based decision-tree model, the financial and clinical impact of implementing all variants of LVDS, PR, PORt, and SBC described in FDA guidance were evaluated from a hospital perspective. Hospitals were assumed to acquire leukoreduced apheresis platelets, with LVDS adding $30 per unit. Monte Carlo simulations were run to estimate the direct medical costs for platelet acquisition, testing, transfusion, and possible complications associated with each approach. Input parameters, including test sensitivity and specificity, were drawn from existing literature and costs (2018US$) were based on a hospital perspective. A one-way sensitivity analysis varied the assumed additional cost of LVDS.

RESULTS

Under an approach of LVDS (7-day), the total cost per transfused unit is $735.78, which falls between estimates for SBC (7-day) and PORt. Assuming 20,000 transfusions each year, LVDS would cost $14.72 million annually. Per-unit LVDS costs would need to be less than $22.32 to be cheaper per transfusion than all other strategies, less than $32.02 to be cheaper than SBC (7-day), and less than $196.19 to be cheaper than PR (5-day).

CONCLUSIONS

LVDS is an effective and cost-competitive approach, assuming additional costs to blood centers and associated charges to hospitals are modest.

Assessment of Time-Dependent Platelet Activation Using Extracellular Vesicles, CD62P Exposure, and Soluble Glycoprotein V Content of Platelet Concentrates with Two Different Platelet Additive Solutions

Novel analytical measures are needed to accurately monitor the properties of platelet concentrates (PCs). Since activated platelets produce platelet-derived extracellular vesicles (EVs), analyzing EVs of PCs may provide additional information about the condition of platelets. The prospect of using EVs as an auxiliary measure of platelet activation state was investigated by examining the effect of platelet additive solutions (PASs) on EV formation and platelet activation during PC storage. The time-dependent activation of platelets in PCs with PAS-B or with the further developed PAS-E was compared by measuring the exposure of CD62P by flow cytometry and the content of soluble glycoprotein V (sGPV) of PCs by an immunoassay. Changes in the concentration and size distribution of EVs were determined using nanoparticle tracking analysis. A time-dependent increase in platelet activation in PCs was demonstrated by increased CD62P ex-posure, sGPV content, and EV concentration. Using these strongly correlating parameters, PAS-B platelets were shown to be more activated compared to PAS-E platelets. Since the EV concentration correlated well with the established platelet activation markers CD62P and sGPV, it could potentially be used as a complementary parameter for platelet activation for PCs. More detailed characterization of the resulting EVs could help to understand how the PC components contribute the functional effects of transfused PCs.

Financial impact of alternative approaches to reduce bacterial contamination of platelet transfusions

BACKGROUND

Bacterial contamination of platelets remains the leading infectious risk from blood transfusion. Pathogen reduction (PR), point-of-release testing (PORt), and secondary bacterial culture (SBC) have been proposed as alternative risk control strategies, but a comprehensive financial comparison has not been conducted.

STUDY DESIGN AND METHODS

A Markov-based decision tree was constructed to model the financial and clinical impact of PR, PORt, and SBC, as well as a baseline strategy involving routine testing only. Hospitals were assumed to acquire leukoreduced apheresis platelets on Day 3 after collection, and, in the base case analysis, expiration would occur at the end of Day 5 (PR and SBC) or 7 (PORt). Monte Carlo simulations assessed the direct medical costs for platelet acquisition, testing, transfusion, and possible complications. Input parameters, including test sensitivity and specificity, were drawn from existing literature, and costs (2018 US dollars) were based on a hospital perspective.

RESULTS

The total costs per unit acquired by the hospital under the baseline strategy, PR, PORt, and SBC were $651.45, $827.82, $686.33, and $668.50, respectively. All risk-reduction strategies decreased septic transfusion reactions and associated expenses, with the greatest reductions from PR. PR would add $191.09 in per-unit acquisition costs, whereas PORt and SBC would increase per-unit testing costs by $31.79 and $17.26, respectively. Financial outcomes were sensitive to platelet dating; allowing 7-day storage with SBC would lead to a cost savings of $12.41 per transfused unit. Results remained robust in probabilistic sensitivity analyses.

CONCLUSIONS

All three strategies are viable approaches to reducing bacterially contaminated platelet transfusions, although SBC is likely to be the cheapest overall.

Atypical Bacterial Growth within Units of Platelets Challenges Transfusion Medicine Dogma

Although transfusion-transmitted bacterial infection is relatively rare, mitigation of bacterial contamination of platelet units is arguably the top current transfusion-related safety concern. Several different technologies have been employed to detect or neutralize bacteria in platelet concentrates. However, studies of the efficacy of these systems have been hampered by problematic definitions of what represents a "true-positive" versus a "false-positive" culture result. In the current issue of the Journal of Clinical Microbiology (M. Cloutier, M.-È. Nolin, H. Daoud, A. Jacques, M. J. de Grandmont, É Ducas, G. Delage, and L. Thibault, J Clin Microbiol 56:e01105-18, 2018, https://doi.org/10.1128/JCM.01105-18), it was demonstrated that the growth of Bordetella holmesii is inhibited by the platelet storage environment, which may explain why the results of initial positive platelet cultures are not always confirmed by subsequent cultures later during the storage period. This important finding is at odds with the generally held belief within the field of transfusion medicine that initially positive platelet cultures that are not confirmed on repeat testing are instrumentation-based false positives. The clinical risk profile of organisms demonstrating storage-related low viability is worthy of further study.

Bordetella holmesii Contamination of Platelet Concentrates: Revisiting the Definition of a Positive Culture

Bacterial contamination remains the most important infectious risk of platelet transfusion. After an initially positive result, a second test is performed on the blood products and the initial culture bottle to confirm the contamination. Based on the blood center's decision algorithm used, results can be either confirmed negative, positive, or indeterminate, or be unconfirmed or discordant. Here, we report the first cases of platelet concentrates contaminated with Bordetella holmesii The in vitro growth characteristics of this unusual contaminant in platelet concentrate were investigated. Two B. holmesii strains isolated from platelet concentrates, as well as a control strain (Serratia marcescens), were spiked into platelet concentrates (PCs) at 1 and 10 CFU/ml. PCs were stored at 20 to 24°C under agitation. Samples were collected on days 2, 3, 4, and 7 for colony count and for bacterial screening using the BacT/Alert 3D system. Two PCs were detected as being positive for B. holmesii However, recultures were negative. In vitro, B. holmesii did not grow but remained detectable in PCs. Its viability diminished rapidly in contact with human plasma. Upon screening using the BacT/Alert 3D system, the majority of products spiked with B. holmesii were negative. This is the first description of PCs contaminated with B. holmesii This bacterium survives in blood products and remains dormant at low concentrations in blood products stored at room temperature, thus making difficult its detection with the BacT/Alert 3D system. The present definition of a true-positive culture of PCs may be overly restrictive for certain bacterial strains.

In vivo viability of extended 4°C-stored autologous apheresis platelets

BACKGROUND

The current 5-day storage time of room temperature (22°C)-stored platelets (RSPs) severely limits platelet (PLT) availability. Extended cold (4°C)-stored PLTs (CSPs) are currently being investigated for actively bleeding patients. However, we currently do not know how to best store PLTs in the cold for extended periods of time. In this study, we investigate how storage in plasma and PLT additive solutions (PASs) affects PLT viability in vivo.

STUDY DESIGN AND METHODS

Twenty normal subjects had a 2-unit hyperconcentrated apheresis PLT collection. One unit was stored at 4°C in plasma for 3 days ("control unit"), and the CSP "test" unit was stored for 10 or 15 days in plasma or 10 days in 35% plasma with either 65% Intersol or Isoplate. After storage, all units were radiolabeled and transfused into their donors.

RESULTS

For 10-day storage, both the plasma and the Intersol units had significantly better PLT recoveries than the Isoplate units (24% ± 8% vs. 11% ± 3% [55% ± 11% vs. 21% ± 8% as percentage of control data], p = 0.002; and 18% ± 4% vs. 11% ± 3% [43% ± 6% vs. 21% ± 8% as percentage of control data], p = 0.004, respectively). There was a trend for lower PLT recoveries with Intersol compared to plasma (p = 0.056). PLT survivals and most in vitro measurements did not differ significantly among the units.

CONCLUSIONS

While the in vitro variables suggest largely comparable results between plasma and PASs, in vivo recoveries were higher with plasma compared with both Intersol and Isoplate (p = 0.057 and p = 0.002, respectively). Whether this difference leads to clinically relevant differences in hemostatic efficacy remains to be determined.

Platelet Transfusion for Patients With Cancer: American Society of Clinical Oncology Clinical Practice Guideline Update

Purpose

To provide evidence-based guidance on the use of platelet transfusion in people with cancer. This guideline updates and replaces the previous ASCO platelet transfusion guideline published initially in 2001.

Methods

ASCO convened an Expert Panel and conducted a systematic review of the medical literature published from September 1, 2014, through October 26, 2016. This review builds on two 2015 systematic reviews that were conducted by the AABB and the International Collaboration for Transfusion Medicine Guidelines. For clinical questions that were not addressed by the AABB and the International Collaboration for Transfusion Medicine Guidelines (the use of leukoreduction and platelet transfusion in solid tumors or chronic, stable severe thrombocytopenia) or that were addressed partially (invasive procedures), the ASCO search extended back to January 2000.

Results

The updated ASCO review included 24 more recent publications: three clinical practice guidelines, eight systematic reviews, and 13 observational studies.

Recommendations

The most substantial change to a previous recommendation involved platelet transfusion in the setting of hematopoietic stem-cell transplantation. Based on data from randomized controlled trials, adult patients who undergo autologous stem-cell transplantation at experienced centers may receive a platelet transfusion at the first sign of bleeding, rather than prophylactically. Prophylactic platelet transfusion at defined platelet count thresholds is still recommended for pediatric patients undergoing autologous stem-cell transplantation and for adult and pediatric patients undergoing allogeneic stem-cell transplantation. Other recommendations address platelet transfusion in patients with hematologic malignancies or solid tumors or in those who undergo invasive procedures. Guidance is also provided regarding the production of platelet products, prevention of Rh alloimmunization, and management of refractoriness to platelet transfusion ( www.asco.org/supportive-care-guidelines and www.asco.org/guidelineswiki ).

Refrigerated platelets for the treatment of acute bleeding: a review of the literature and reexamination of current standards

This review is a synopsis of the decisions that shaped global policy on platelet (PLT) storage temperature and a focused appraisal of the literature on which those discussions were based. We hypothesize that choices were centered on optimization of preventive PLT transfusion strategies, possibly to the detriment of the therapeutic needs of acutely bleeding patients. Refrigerated PLTs are a better hemostatic product, and they are safer in that they are less prone to bacterial contamination. They were abandoned during the 1970s because of the belief that clinically effective PLTs should both be hemostatically functional and survive in circulation for several days as indicated for prophylactic transfusion; however, clinical practice may be changing. Data from two randomized controlled trials bring into question the concept that stable autologous stem cell transplant patients with hypoproliferative thrombocytopenia should continue to receive prophylactic transfusions. At the same time, new findings regarding the efficacy of cold PLTs and their potential role in treating acute bleeding have revived the debate regarding optimal PLT storage temperature. In summary, a "one-size-fits-all" strategy for PLT storage may not be adequate, and a reexamination of whether cold-stored PLTs should be offered as a widely available therapeutic product may be indicated.

Biofilm formation by Staphylococcus capitis strains isolated from contaminated platelet concentrates

Bacterial contamination of platelet concentrates (PCs) poses the greatest infectious risk in modern transfusion medicine despite the implementation of measures such as improved skin disinfection and first aliquot diversion. The majority of PC contaminants are commensal skin flora introduced by venipuncture at the time of blood collection. The predominant organisms are Gram-positive coagulase-negative staphylococci such as Staphylococcus capitis. This bacterium has been implicated in numerous instances of infection and sepsis, likely for its ability to form surface-associated communities of micro-organisms encased in extracellular materials, known as biofilms. In the present study, five strains of S. capitis isolated from contaminated PCs were assessed for their ability to produce extracellular polysaccharide (slime), a canonical indicator of biofilm-formation ability, on Congo red agar plates. Biofilm formation was evaluated in both glucose-enriched trypticase soy broth (TSBg) and in PCs by using a crystal violet staining assay. The chemical nature of the biofilms was evaluated by disruption assays using sodium metaperiodate and proteinase K. In addition, biofilm architecture was observed by scanning electron microscopy. The presence of the biofilm-associated icaR and icaADBC genes was also examined by PCR. While only two out of the five S. capitis strains formed biofilms in TSBg, all strains formed biofilms in PCs. The ability of strains to produce extracellular polysaccharide and their possession of wild-type ica genes were not exclusive predictors of biofilm formation in TSBg or PCs; different profiles of biofilm markers were observed among isolates. This is likely due to the proteinaceous composition of the S. capitis biofilm matrix. Interestingly, an ica-negative, non-slime-producing isolate was capable of biofilm formation in PCs. Together, these data indicate that the platelet storage environment stimulates biofilm formation in S. capitis in the absence of extracellular polysaccharide production and that multiple bacterial factors and regulatory elements are likely involved in biofilm formation in this milieu.

Enhanced pathogenicity of biofilm-negative Staphylococcus epidermidis isolated from platelet preparations

BACKGROUND

The platelet (PLT) storage environment triggers the formation of surface-attached aggregates known as biofilms by the common PLT contaminant Staphylococcus epidermidis. The biofilm matrix is largely composed of polysaccharide intercellular adhesin (PIA) mediated by the icaADBC operon. However, PIA-negative S. epidermidis has been reported to form biofilms in PLT concentrates (PCs). Since biofilm formation is associated with increased virulence, this study was aimed at determining if PIA-negative S. epidermidis grown in PCs presents enhanced virulence using the nematode Caenorhabditis elegans as a host model for bacterial pathogenesis.

STUDY DESIGN AND METHODS

Biofilm-positive S. epidermidis ATCC 35984 and 9142, which carry the icaADBC operon, and biofilm-negative S. epidermidis ATCC 12228 and 9142 ΔicaA were grown in regular media and in PCs and biofilm formation was quantified using a crystal violet assay. The virulence of these strains after passage through PCs was tested using nematode killing assays. Nematode survival was calculated using the Kaplan-Meier method and statistical differences were determined by log-rank analysis.

RESULTS

All S. epidermidis strains were able to form biofilms in PCs. Although persistence of a biofilm-positive phenotype in the biofilm-negative strains grown in PCs was not observed after passage in regular medium, the virulence of all strains was significantly increased as demonstrated by shortened life spans of the nematodes in C. elegans killing assays.

CONCLUSION

Our findings highlight the potential of an increased risk of nosocomial infections caused by S. epidermidis in transfusion recipients since PC storage conditions promote biofilm formation, and possibly pathogenicity, of strains traditionally known to be attenuated for virulence.

Listeria monocytogenes in donated platelets: a potential transfusion-transmitted pathogen intercepted through screening

BACKGROUND

Bacterial contamination of blood components is a potentially life-threatening complication of transfusions. In October 2005, the Centers for Disease Control and Prevention (CDC) noted four Listeria monocytogenes (Lm) isolates cultured from four different units of donated apheresis platelets (PLTs) among Lm isolates sent to the CDC National Listeria Reference Laboratory for subtyping as part of routine surveillance activities.

STUDY DESIGN AND METHODS

We describe an investigation to determine possible common sources of infection among donors or factors associated with PLT collection or storage and to determine whether human transfusion-associated listeriosis cases had been reported. We also reviewed all isolates with PLTs as a source sent to the CDC National Listeria Reference Laboratory between November 1, 2005, and December 31, 2011.

RESULTS

Each PLT donor-associated isolate had a distinct pulsed-field gel electrophoresis pattern combination. Other than these four cases, no other cases of Lm-contaminated PLTs were identified by the American Red Cross or by CDC during 2005. However, two additional cases of Lm isolated from donated PLTs were detected, one in 2008 and one in 2011.

CONCLUSION

Although the source of contamination for these PLT units is unclear, and a source common to all units was not identified, this investigation underscores the value of screening for bacterial contaminants of PLTs.

Preservation of Platelets by Adding Epigallocatechin-3-O-Gallate to Platelet Concentrates

The effect of epigallocatechin-3- O-gallate (EGCG), a major component of green tea, on platelet preservation was evaluated. Single donor platelets ( N = 10) were collected and preserved by the standard method. EGCG was added to the platelet concentrates before preservation and then the functional and biochemical parameters were monitored throughout the storage period. After 6 days of preservation, the aggregability of the platelets was significantly maintained by addition of 50 and 100 μg/ml of EGCG. Platelet prothrombinase activity was also significantly retained by the addition of EGCG. The accumulation of P-selectin and RANTES in the plasma preserved with EGCG was less than those preserved without EGCG, which indicated that EGCG might inhibit platelet activation. Furthermore, EGCG reduced the increase of LDH in plasma during preservation and inhibited the activation of caspase-3 and cleavage of gelsolin, thereby showing that EGCG could inhibit the apoptosis of platelets. These results suggest that EGCG may play an effective role in preserving platelets by inhibiting the activation and apoptosis of platelets.

Enrichment of human platelet membranes for proteomic analysis

Platelets (thrombocytes) are the smallest human blood cells and are pivotal in processes of hemostasis and thrombosis. Central to their function, the activation of platelets includes a complex interplay of adhesion and signalling molecules mediated via the plasma and inner membrane. Because platelets are enucleated, the analysis of the proteome is the best way to approach their biology. Here, we employ mass spectrometry (MS)-based proteomics to characterise membrane proteins derived from non-stimulated human platelets. This protocol details the extraction and purification of platelet membrane proteins from whole blood using SDS-PAGE in conjunction with LC-MS/MS. This method allowed the identification, and characterization of 207 platelet membrane proteins (PMP) from approximately 9.95 x 10(9) platelets (16).

Bacterial screening of apheresis platelets and the residual risk of septic transfusion reactions: the American Red Cross experience (2004-2006)

BACKGROUND

The American Red Cross initiated systemwide bacterial testing of all apheresis platelet (PLT) collections in March 2004, yet continues to receive reports of septic reactions after transfusion of screened components.

STUDY DESIGN AND METHODS

The rates of confirmed bacterial contamination of apheresis PLT collections detected by prospective quality control (QC) testing, and by surveillance of reported septic reactions to screened-negative apheresis PLTs, were analyzed according to the technology utilized for collection.

RESULTS

Between March 1, 2004, and May 31, 2006, bacterial culture testing was performed on 1,004,206 donations; of these, 186 (1:5,399) had confirmed-positive culture results. Transfusion of all but 1 of the associated 293 components was prevented. A significantly higher rate of confirmed-positive bacterial cultures was seen with products collected utilizing two-arm collection procedures compared to one-arm procedures (22.7 vs. 11.9 per 10(5) donations; odds ratio [OR], 1.9; 95% confidence interval [CI], 1.4-2.7). During this period, 20 septic transfusion reactions were reported, including 3 fatalities (1:498,711 fatalities per distributed component), which implicated screened-negative apheresis PLT products. The frequency of septic reactions was 4.7-fold higher for collections utilizing two-arm procedures (1:41,173; 95% CI, 1:25,000-1:66,667) compared to collections from one-arm procedures (1:193,305; 95% CI, 1:52,632-1:500,000; OR, 4.7; 95% CI, 1.2-18.4); most septic reactions (16 of 20) were due to Staphylococcus spp. and occurred on Day 5 (13 of 20) after collection.

CONCLUSION

PLT contamination with bacteria that evade detection by QC culture remains a significant residual transfusion risk, in particular for older PLTs and skin-commensal bacteria in components collected by two-arm apheresis procedures during the study period.

Platelet audit: Assessment and utilization of this precious resource from a tertiary care hospital

BACKGROUND

To assess the appropriate utilization of platelet transfusions [random donor platelets (RDP) and single donor platelets (SDP)]; a six-month retrospective audit was carried out in a tertiary care hospital.

MATERIALS AND METHODS

A six-month retrospective platelet audit was carried out from May to October 2005 to estimate its preparation, appropriate utilization and wastage rate. Patient's demographics, transfusion triggers and episodes and ABO and Rh (D) group specific or non-group specific transfusions were also assessed.

RESULTS

About 5525 units of platelets [PRP-PC, 3,813 (69%); BC-PC, 983 (17.8%); PRP, 648 (11.7%) and SDP 81 (1.5%)] were prepared and transfused to 853 patients (RDP to 814 patients and SDP to 39 patients) in 2,093 transfusion episodes. Adult and pediatric hemato-oncology were the main user specialties utilizing 39.1 and 87.6% of the RDPs and SDPs prepared. Of the patients receiving RDPs, 95% were transfused ABO and Rh (D) group specific platelets whereas 100% SDPs transfusions were of group specific platelets. 88% of prophylactic platelet transfusions were appropriate as per the recommended BCSH guidelines. However, 12% of the prophylactic platelets were transfused inappropriately in cardiopulmonary bypass (CPB) surgeries with normal platelet counts and no evidence of bleeding related to platelets. Out of 5,444 RDPs prepared 1,585 (29.11%) units were not utilized.

CONCLUSIONS

Regular audit of blood and blood components is a must so that necessary remedial measures can be taken to maximize appropriate and judicious utilization of each component.

Evolution of surveillance methods for detection of bacterial contamination of platelets in a university hospital, 1991 through 2004

BACKGROUND

Platelet (PLT) bacterial contamination (PBC) is the most common transfusion-associated infection. It is important to understand the impact of interventions addressing this problem.

STUDY DESIGN AND METHODS

PBC was studied by prospective (active) and transfusion-reaction triggered (passive) surveillance from July 1991 to December 2004. Active surveillance, utilized for 10 years, included bacterial culture of all or 4- and 5-day-old PLTs at issue and intermittent use of Gram stain, pH measurements, and early (24-hr) culture of single-donor plateletpheresis (SDP) units.

RESULTS

Active surveillance detected 38 instances of PBC, 7 in SDP units (1:2213) and 31 in random-donor PLT units (1:2090 units, p = 0.89; or 1:418 pools of 5 units, p < 0.001). Contaminants were coagulase-negative staphylococci (CONS; n = 27), Staphylococcus aureus (4), Bacillus cereus (1), Serratia marcescens (2), streptococci (2 S. bovis, 1 S. uberis), and CONS with viridans group streptococcus (1). Only one instance of contamination, caused by Pseudomonas aeruginosa, was detected by passive surveillance, with fatal outcome. Colony counts of contaminants ranged from 0.5 x 10(2) to 4 x 10(11) colony-forming units per mL at time of issue. PBC was interdicted before transfusion in 6 cases through Gram stain screening. Transfusion reactions occurred in 13 of 32 recipients (41%), with 9 severe reactions (28%) and 3 deaths (9%). pH testing failed to detect 5 contaminated units and resulted in discard of nearly 2 percent of units, whereas culture of SDP units at 24 hours failed to identify a contaminated unit.

CONCLUSION

Improved active surveillance methods for detecting PBC are needed to improve the safety of PLT transfusions.

Transfusion of 7-day-old amotosalen photochemically treated buffy-coat platelets to patients with thrombocytopenia: a pilot study

BACKGROUND

Photochemical treatment (PCT) of platelets (PLTs) with amotosalen and ultraviolet A light to inactivate bacteria may facilitate extension of storage from 5 to 7 days.

STUDY DESIGN AND METHODS

A randomized, double-blinded, crossover, noninferiority, single-site pilot study utilizing pooled buffy-coat PLTs was conducted. The primary endpoint was the 1-hour corrected count increment (CCI) after one transfusion each of 7-day-old PCT and reference (R) PLT components. Secondary endpoints included 1-hour count increment, time to next transfusion, hemostasis, transfusion reactions, and serious adverse events.

RESULTS

Twenty patients with thrombocytopenia were randomly assigned: 9 to the PCT-R sequence and 11 to the R-PCT sequence. A significant treatment-by-period interaction was observed. Therefore, the first period only was also analyzed for the primary endpoint. Including both treatment periods, mean 1-hour CCI was 6587 +/- 4531 for PCT versus 8935 +/- 5478 for R-PLTs. For the first period only, mean 1-hour CCI was 8739 +/- 3785 for PCT versus 7433 +/- 5408 for R-PLTs. The upper bound of the one-sided 95 percent confidence interval of 2400 for the mean difference was higher than the specified noninferiority margin of 2200 for both analyses. Overall median time to next transfusion was 22 hours for PCT versus 27 hours for R-PLTs. Hemostasis was adequate and no transfusion reactions or serious adverse events were reported.

CONCLUSIONS

Although this pilot study of a limited number of patients failed to show noninferiority within the specified noninferiority margin, 7-day-old PCT PLTs showed acceptable efficacy and safety for support of thrombocytopenia. The results, however, warrant evaluation in a larger trial of 7-day-old PCT PLTs.

Infectious complications after cardiac surgery: lack of association with fresh frozen plasma or platelet transfusions

OBJECTIVE

The purpose of this study was to examine the effect of perioperative transfusion of platelets and fresh frozen plasma (FFP) on infection rates after cardiac surgery.

DESIGN

Retrospective study comparing infection rates after cardiac surgery among patients receiving combinations of packed red blood cells (PRBCs), platelets, and FFP.

SETTING

Tertiary care university teaching hospital.

PARTICIPANTS

All elective primary coronary artery bypass (CABG) surgery patients from July 1995 to January 1998 before introduction of leukocyte-reduced blood products.

INTERVENTIONS

Multivariate logistic and linear regression models were applied to identify clinical risk factors for postoperative infection and to determine the relationship between perioperative administration of PRBCs, platelets, and FFP with postoperative infection.

MEASUREMENTS AND MAIN RESULTS

Transfusion of PRBCs, diabetes, age, preoperative hematocrit, and the duration of cardiopulmonary bypass were significantly associated with postoperative infection; platelet or FFP transfusion added no additional risk to PRBC transfusion alone.

CONCLUSIONS

Infectious complications in a population of adult primary CABG surgery patients were not increased by transfusion of platelets or FFP. It is PRBC transfusion that confers an increased risk of postoperative infection in this population.

Streptococcus bovis septic shock due to contaminated transfused platelets

Although most physicians and the public are primarily concerned about the risk of transmitting human immunodeficiency virus (HIV) or hepatitis virus during a platelet transfusion, bacterial contamination is actually the most common infectious complication. Unlike red blood cells, platelets are stored at room temperature (20-24 degrees C), which raises the risk of bacterial proliferation. The risk of bacterial sepsis is 2.5-fold higher for each unit of transfused platelets compared to each unit of red blood cells. We report an unusual case of Streptococcus bovis septic shock associated with a contaminated platelet transfusion.

Detection of bacterial contamination of platelet components: six years’ experience with the BacT/ALERT system

BACKGROUND

Hemovigilance has shown that bacteria cause more fatalities than other infections together. Surveillance for detection of bacteria in platelets (PLTs) was initiated. Concomitantly, the storage period for PLTs was extended from 5 to 7 days to reduce cost.

STUDY DESIGN AND METHODS

Analysis was performed of all cases of a positive signal in a screening procedure for contaminated PLTs taking into account results of confirmative cultures and results of culture from blood components including bacteria strains. Records were assessed from patients transfused with blood components issued before the screening culture became positive.

RESULTS

Samples were collected from 22,057 PLT units. An initial reaction was seen in 84 (0.38%). Growth was confirmed in 70 of these. Of the associated PLT units, 26 had been issued or outdated at the time when the culture was found to be reactive, in 27 bacteria were found, and in 17 cultures were negative. The bacteria found were mainly from normal skin flora. Sixty-six patients received 75 blood components issued before the screening system alarmed. None of these patients had a transfusion reaction reported. The outdating fell to less than 5 percent.

CONCLUSION

A screening system for detection of bacterial contamination was implemented without increase in cost owing to extension of storage time to 7 days. Transfusion of several contaminated blood components was prevented.

Estimation of bacterial risk in extending the shelf life of PLT concentrates from 5 to 7 days

BACKGROUND

The use of bacterial culture to prevent bacterial contamination of blood components has renewed interest for extending the shelf life of PLT concentrates to 7 days after collection.

STUDY DESIGN AND METHODS

This study was therefore conducted to determine the residual risk of bacterial contamination in PLT concentrates at the end of 5 and 7 days after collection in a center where all PLT concentrates are routinely screened by taking samples on Day 2 for culture. PLT units with no growth after 48 hours were sampled a second time on Day 5 or Day 7 after collection, followed by inoculation into aerobic culture bottles. The inoculated bottles were then monitored for up to 7 days at 35 degrees C in an automatic monitoring and detection system.

RESULTS

During a 16-month study period, a total of 6020 PLT concentrates were tested 5 days (Group A, n=3010) and 7 days (Group B, n=3010) after collection. Four units in each group (0.133%) were found to be contaminated. In 6 units, bacteria were seen on direct Gram stain. In addition, 5 of the associated RBC units grew the same organisms on culture. The organisms include three coagulase-negative staphylococci and five Propionibacterium acnes. The positive rate of routine short-term bacterial culture was 0.035 percent during the same study period.

CONCLUSION

Despite routine short-term bacterial culture, a significant risk of bacterial contamination remains at 5 and 7 days after collection. For now, the shelf life of PLT concentrates should remain 5 days.

Warming of infusion syringes caused by electronic syringe pumps

PURPOSE

To evaluate inadvertent warming of the infusion syringe in four different types of electronic syringe pumps.

METHODS

Ambient temperature and syringe surface temperature were simultaneously measured by two electronic temperature probes in four different models of commercially available syringe pumps. Experiments were performed at an infusion rate of 1 ml h(-1) using both battery-operated and main power-operated pumps. Measurements were repeated four times with two pumps from each of the four syringe pump types at a room temperature of approximately 23 degrees C. Differences among the four syringe pump brands regarding ambient to syringe temperature gradient were compared using ANOVA. A P-value of less than 0.05 was considered statistically significant.

RESULTS

Syringe warming differed significantly between the four syringe brands for both the battery-operated and main power-operated mode (ANOVA, P< 0.001 for both modes). Individual differences between syringe surface and ambient temperature ranged from 0.3 to 1.9 degrees C for battery operation and from 0.5 to 11.2 degrees C during main-power operation.

CONCLUSION

Infusion solutions can be significantly warmed by syringe pumps. This has potential impact on bacterial growth and the stability of drug solutions and blood products infused, as well as on the susceptibility to hydrostatic pressure changes within the infusion syringe.

Seven-day storage of single-donor platelets: recovery and survival in an autologous transfusion study

BACKGROUND

Bacterial screening may effectively reduce the morbidity and mortality risk associated with extended storage of platelets. Platelet viability then becomes the primary determinant of acceptable storage time. This study evaluates the effectiveness of platelets stored in plasma for 7 days.

STUDY DESIGN AND METHODS

WBC-reduced, single-donor platelets (n = 24) were collected and stored by standard methods at two sites. Standard in vitro platelet biochemical and functional parameters were monitored over the storage period. On Days 5 and 7 of storage, platelets were alternately labeled with 51Cr and (111)In and returned to the subject, and recovery and survival were determined.

RESULTS

Component pH(22 degrees C) was maintained in the range 6.2 to 7.61 through 7 days and did not detrimentally affect either in vitro or in vivo outcomes. In vitro platelet characteristics were adequately maintained over 7 days. Day 5 platelets had better recovery (63.0 +/- 4.36 vs. 53.9 +/- 4.36%, p < 0.0001) and survival (161 +/- 8.1 vs. 133 +/- 8.1 hr, p = 0.006) than Day 7 platelets adjusting for radioisotope, center, and donor effects.

CONCLUSION

Although declines in recovery and survival were noted, these are less than used previously to gain licensure of 7-day storage and are unlikely to be clinically significant. Extension of storage to 7 days could be implemented with bacterial screening methods to select out contaminated components without a significant effect on the platelet efficacy compared to 5-day components.

Methicillin-resistant Staphylococcus aureus sepsis associated with the transfusion of contaminated platelets: a case report

BACKGROUND

Platelet transfusion-associated sepsis is usually due to donor skin flora introduced into the unit during phlebotomy. An unusual case of a platelet component contaminated with methicillin-resistant Staphylococcus aureus (MRSA) is reported.

CASE REPORT

A 54-year-old man, terminally ill with progressive non-Hodgkin's lymphoma, developed fever and hypotension during a platelet transfusion. He was receiving multiple antibiotics, including vancomycin. Blood cultures taken soon after transfusion were negative. An aliquot taken from the platelet pool grew MRSA at a count of 1.6 x 10(8) CFUs per mL. One of the individual bags constituting the pool showed MRSA at a count of 5.1 x 10(8) CFUs per mL. The patient died soon after the platelet transfusion. This case was reported to the FDA and submitted to the BaCon Study. The identity of the isolate and its methicillin resistance were confirmed by the CDC as part of the BaCon Study protocol. The source of contamination of the implicated unit could not be established with certainty.

CONCLUSION

The emergence of antimicrobial-resistant organisms poses additional challenges for the diagnosis and treatment of transfusion-associated sepsis. Measures to prevent or intercept the transfusion of contaminated platelets should be developed.

The evaluation of microbial contamination in platelet concentrates prepared by two different methods

The microbial contamination of platelet concentrates (PCs) prepared by two different methods both with a high risk of bacterial contamination during preparation and storage were evaluated. For apheresis platelets, the concentrates were obtained using the Haemonetics MCS 3P device. For the random method, platelets were obtained by two phase centrifugation, in the Heraeus Cryofuge 8500 I device using the Kansuk 3-way bags which permit storage for five days. 1620 plateletpheresis units prepared by apheresis, and 9838 units prepared by the random method, were included in the study. Of the 11,458 PCs studied. 32 (0.27%) were false positives and 24 (0.2%) were real positives. All of the positive results occurred in platelets prepared by the random method. C. xerosis and S. epidermidis, S. hominis, Alpha-hemolytic streptococci, all flora of the skin, were isolated in the contaminated concentrates. The risk of microbial contamination of PCs, prepared both by apheresis and from whole blood, continues at a low rate although the products were collected into specific bags following rules including appropriate disinfection of the skin, correct centrifugation collection time and optimal storage conditions including temperature and agitation. These results again emphasize the importance of: obeying phlebotomy rules and hand disinfection of the person who collects the blood as well as the need for careful skin decontamination of the donor, during donation.

Single-donor platelets reduce the risk of septic platelet transfusion reactions

BACKGROUND

Septic platelet transfusion reactions (SPTRs) are the most common, serious risk of transfusion. Because SPTRs result from donor skin flora or asymptomatic bacteremia, the use of single-donor platelets (SDPs) has been proposed to reduce the risk of SPTRs from the risks with pools of platelet concentrates (PCs).

STUDY DESIGN AND METHODS

Beginning in 1986, all febrile transfusion reactions were evaluated by culture of the platelet bag. Confirmed SPTRs were identified by isolation of the same bacteria from the bag and the patient's blood or by positive Gram's stain of the bag that confirmed a positive platelet culture. In 1987, a program to minimize PC use in favor of SDP use was initiated as a means of reducing SPTRs.

RESULTS

In 12 years, the use of SDPs increased from 51.7 percent to 99.4 percent of all platelet transfusions at one institution. SPTRs fell from three events in 1 year to the current rate of one event per year. The incidence of SPTRs decreased from 1 in 4,818 transfusions to 1 in 15,098 transfusions. The rate of SPTRs due to PCs was 5.39 times higher than that of SPTRs due to SDPs (95% CI, 1.89,12.9).

CONCLUSION

The use of SDPs is a simple means of reducing SPTRs. Other measures such as sterilization will be required to eliminate all SPTRs.

Determinants of transfusion-associated bacterial contamination: results of the French BACTHEM Case-Control Study

BACKGROUND

Transfusion-associated bacterial contamination (TABC), probably the most frequent transfusion-transmitted infection, may induce serious adverse events. Systematic information and documentation on determinants are lacking.

STUDY DESIGN AND METHODS

The BACTHEM Study is a French matched case-control study assessing TABC determinants. Included were cases of TABC reported in France in a 2-year period, as determined from uniform definitions. Information on recipient-, blood component-, and donor-related potential determinants was collected on site. ORs were estimated by conditional logistic regression.

RESULTS

Of the 158 cases of suspected TABC reported, 41 that involved transfusion with 25 RBCs and 16 platelet concentrates were included. Gram-negative rods accounted for nearly half of the bacteria species involved and for all six deaths. In comparison with the risk of TABC for patients receiving RBCs for anemia, the risk was higher for patients receiving RBCs for pancytopenia (OR, 7.3; 95% CI, 1.3-41.0) and for those receiving platelets for thrombocytopenia (OR, 5.3; 95% CI, 1.2-24.1). Other potential determinants were platelet transfusion for pancytopenia (OR, 4.5; 95% CI, 0.5-40.0), immunosuppressive treatment (OR, 2.8; 95% CI, 0.7-10.6), shelf-life of more than 1 day for platelets or 8 days for RBCs (OR, 2.6; 95% CI, 0.7-9.6), and more than 20 previous donations by donors (OR, 1.9; 95% CI, 0.7-5.3).

CONCLUSION

This first comparative study revealed TABC determinants that suggest approaches for prevention.