Bacterial contamination and septic transfusion reaction rates associated with platelet components before and after introduction of primary culture: experience at a US Academic Medical Center 1991 through 2017.

BACKGROUND: The high incidence of septic transfusion reactions (STRs) led to testing being mandated by AABB from 2004. This was implemented by primary culture of single-donor apheresis platelets (APs) from 2004 and prestorage pooled platelets (PSPPs) from 2007. STUDY DESIGN/METHODS: Platelet (PLT) aliquots were cultured at issue and transfusion reactions evaluated at our hospital. Bacterial contamination and STR rates (shown as rates per million transfusions in Results) were evaluated before and after introduction of primary culture by blood centers that used a microbial detection system (BacT/ALERT, bioMerieux) or enhanced bacterial detection system (eBDS, Haemonetics). RESULTS: A total of 28,457 PLTs were cultured during pre-primary culture periods (44.7% APs; 55.3% at-issue pooled PLTs [AIPPs]) and 97,595 during post-primary culture periods (79.3% APs; 20.7% PSPPs). Forty-three contaminated units were identified in preculture and 34 in postculture periods (rates, 1511 vs. 348; p < 0.0001). Contamination rates of APs were significantly lower than AIPPs in the preculture (393 vs. 2415; p < 0.0001) but not postculture period compared to PSPPs (387 vs. 198; p = 0.9). STR rates (79 vs. 90; p = 0.98) were unchanged with APs but decreased considerably with pooled PLTs (826 vs. 50; p = 0.0006). Contamination (299 vs. 324; p = 0.84) and STR rates (25 vs. 116; p = 0.22) were similar for PLTs tested by BacT/ALERT and eBDS primary culture methods. A change in donor skin preparation method in 2012 was associated with decreased contamination and STR rates. CONCLUSION: Primary culture significantly reduced bacterial contamination and STR associated with pooled but not AP PLTs. Measures such as secondary testing near time of use or pathogen reduction are needed to further reduce STRs.

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.

Bacterial contamination rate of platelet components by primary culture: a systematic review and meta-analysis.

BACKGROUND: Platelets have the highest bacterial contamination risk of all blood components, and septic transfusion reactions remain a problem. A good estimate of contamination rates could provide information about residual risk and inform optimal testing strategies. We performed a systematic review and meta-analysis of platelet contamination rates by primary culture. STUDY DESIGN AND METHODS: A literature search in December 2019 identified articles on platelet contamination rates using primary culture. We used meta-analysis to estimate the overall rate of contamination and meta-regression to identify heterogeneity. We studied the following sources of heterogeneity: collection method, sample volume, positivity criteria, and study date. Contamination rate estimates were obtained for apheresis (AP), platelet rich plasma (PRP), and buffy coat (BC) collection methods. RESULTS: The search identified 6102 studies, and 22 were included for meta-analysis. Among these 22 studies, there were 21 AP cohorts (4,072,022 components), 4 PRP cohorts (138,869 components), and 15 BC cohorts (1,474,679 components). The overall mean contamination rate per 1000 components was 0.51 (95% CI: 0.38-0.67) including AP (0.23, 95% CI: 0.18-0.28), PRP, (0.38, 95% CI: 0.15-0.70), and BC (1.12, 95% CI: 0.51-1.96). There was considerable variability within each collection method. Sample volume, positivity criteria, and publication year were significant sources of heterogeneity. CONCLUSION: The bacterial contamination rate of platelets by primary culture is 1 in 1961. AP and PRP components showed a lower contamination rate than BC components. There is clinically significant between-study variability for each method. Larger sample volumes increased sensitivity, and bacterial contamination rates have decreased over time.

Heterogeneity of Human Pancreatic Islet Isolation Around Europe: Results of a Survey Study.

BACKGROUND: Europe is currently the most active region in the field of pancreatic islet transplantation, and many of the leading groups are actually achieving similar good outcomes. Further collaborative advances in the field require the standardization of islet cell product isolation processes, and this work aimed to identify differences in the human pancreatic islet isolation processes within European countries. METHODS: A web-based questionnaire about critical steps, including donor selection, pancreas processing, pancreas perfusion and digestion, islet counting and culture, islet quality evaluation, microbiological evaluation, and release criteria of the product, was completed by isolation facilities participating at the Ninth International European Pancreas and Islet Transplant Association (EPITA) Workshop on Islet-Beta Cell Replacement in Milan. RESULTS: Eleven islet isolation facilities completed the questionnaire. The facilities reported 445 and 53 islet isolations per year over the last 3 years from deceased organ donors and pancreatectomized patients, respectively. This activity resulted in 120 and 40 infusions per year in allograft and autograft recipients, respectively. Differences among facilities emerged in donor selection (age, cold ischemia time, intensive care unit length, amylase concentration), pancreas procurement, isolation procedures (brand and concentration of collagenase, additive, maximum acceptable digestion time), quality evaluation, and release criteria for transplantation (glucose-stimulated insulin secretion tests, islet numbers, and purity). Moreover, even when a high concordance about the relevance of one parameter was evident, thresholds for the acceptance were different among facilities. CONCLUSIONS: The result highlighted the presence of a heterogeneity in the islet cell product process and product release criteria.