Analysis of Transfusion-Transmitted Bacterial Infections according to German Hemovigilance Data (2011-2020).

Introduction: Following the first assessment of the effects of safety measures taken against transfusion-transmitted bacterial infections (TTBI), the Paul-Ehrlich-Institut (PEI) decided to newly analyze risk minimization measures (RMM) using German hemovigilance data from 2011 to 2020, focusing on blood components, recipients, and bacterial strains.

Materials and methods: The PEI assessed the imputability of all reported serious adverse reactions (SAR) relying mainly on microbiological test results. Reporting rates (RR) of suspected, confirmed, and fatal confirmed TTBI were calculated and compared to the previous reporting 10-year period (2001-2010) using Poisson regression to estimate RR ratios (RRR). Furthermore, details on blood component age, patients' medical history, and bacterial pathogenicity were collected.

Results: With respect to the previous 10-year period, the number of suspected TTBI increased (n = 403), while fewer cases were confirmed (n = 40); the number of deaths remained more or less unchanged (n = 8). The RR for suspected TTBI were 7.9, 18.7, and 1.6 cases per million units transfused for red blood cells (RBC), platelet concentrates (PC), and fresh frozen plasma (FFP), respectively. RRR showed a statistically significant 2.5-fold increase in the RR for suspected TTBI after RBC administration from 2001-2010 to the period under review (p < 0.0001). The RR for confirmed TTBI were 0.4, 5.0, and 0.0 cases per million units transfused for RBC, PC, and FFP, respectively. Compared to the period 2001-2010, there was a statistically significant decrease in the RR of confirmed TTBI by half for PC (p = 0.0052). The RR for confirmed PC-caused TTBI with fatal outcome was 1.4 cases per million units transfused. Regardless of type of blood product transfused and outcome of SAR, the majority of TTBI occurred after administration of a product at the end of shelf life (40.0%) and to recipients of advanced age (median age: 68.5 years) and/or with severe immunosuppression (72.5%) due to decreased myelopoiesis (62.5%). 72.5% of the involved bacteria had a middle/high human pathogenicity.

Conclusion: Despite a significant decrease in confirmed TTBI following PC transfusion in Germany after implementation of RMM, the current manufacture of blood products can still not prevent TTBI with fatal outcomes. As demonstrated in various countries, RMM like bacterial screening or pathogen reduction may measurably improve the safety of blood transfusion.