Genotypic and phenotypic characteristics of Escherichia coli involved in transfusion-transmitted bacterial infections: implications for preventive strategies.

BACKGROUND: Transfusion-transmitted bacterial infections (TTBIs) are the main residual infectious complications of transfusions. Escherichia coli and platelet (PLT) concentrates may be epidemiologically associated, leading to severe, if not lethal, TTBIs. We investigated the genotypic and phenotypic reasons for this clinically deleterious combination. STUDY DESIGN AND METHODS: We investigated a French national E. coli strain collection related to six independent episodes of TTBIs. Their phenotypic characterizations included antibiotic susceptibility testing, growth testing under different culture conditions, serum survival assays, and virulence in a sepsis mouse model. Their genotypic characterizations included polymerase chain reaction phylotyping, whole genome sequencing, and a subsequent in silico analysis. RESULTS: We highlighted a selection process of highly extraintestinal virulent strains, mainly belonging to the B2 phylogroup, adapted to the hostile environment (high citrate concentration and a bactericidal serum effect) of apheresis-collected platelet concentrates (PCs). Compared to controls, the E. coli TTBI strains grew faster in the PCs due to a superior ability to capture iron. The in vitro growth performances were highly compatible with blood-derived product real-life conditions, including storage conditions and delays. The consistent serum resistance of TTBI strains promotes their survival in both the donor's and the receiver's blood and in the PCs. CONCLUSION: This study pointed out that E. coli strains responsible for TTBI exhibit very specific traits. They belong to the extraintestinal pathogenic phylogroups and have a high intrinsic virulence. They can be resistant to complement, capture iron, and grow in the apheresis-collected PCs. These findings therefore support the reinforcement of the postdonation information.

Residual risk and retrospective analysis of transfusion-transmitted bacterial infection reported by the French National Hemovigilance Network from 2000 to 2008.

BACKGROUND: Regarding blood safety, transfusion-transmitted bacterial infection (TTBI) remains the most frequent infectious risk. The incidence of these episodes needs to be assessed and updated frequently to accurately manage this risk. STUDY DESIGN AND METHODS: TTBIs were reported by the French network of local correspondents in each hospital and blood center. The regional coordinator managed the investigation. A multidisciplinary expert group from the French National Agency of Medicine and Health Products Safety (ANSM) analyzed each TTBI according to a standardized scale of imputability and severity. Only cases with likely or certain imputability are reported in this study. RESULTS: In France, 18.0 × 10(6) red blood cell (RBC) products, 1.94 × 10(6) platelet concentrates (PCs), and 2.44 × 10(6) fresh-frozen plasma units were transfused throughout 2000 to 2008. The incidence of TTBI was 2.45, 24.7, and 0.39 per million blood components (BCs), PCs, and RBCs, respectively. For PCs, the incidences of severe (vital threat or death) and fatal TTBI were 13.4 and 5.14 per million, respectively. PCs were responsible for 87% of TTBIs. A total of 66.7% of the implicated bacteria were Gram positive, most of them belonging to the normal skin flora. A total of 33.3% of the other implicated bacteria were Gram negative. CONCLUSION: The French hemovigilance system provides an accurate estimate of the TTBI incidence during a period with diversion and improving skin disinfection but without bacterial detection screening. This tool would be able to evaluate further additional safety procedures like bacterial screening and pathogen reduction technology.

Psychrobacter arenosus bacteremia after blood transfusion, France.

We report a case of transfusion-associated bacteremia caused by Psychrobacter arenosus. This psychrotolerant bacterium was previously isolated in 2004 from coastal sea ice and sediments in the Sea of Japan, but not from humans. P. arenosus should be considered a psychrotolerant bacterial species that can cause transfusion-transmitted bacterial infections.

Impact of transfusion on survival in patients with myelodysplastic syndromes: Current knowledge, new insights and transfusion clinical practice.

Red Blood Cell (RBC) transfusion dependence is a prevalent consequence of anaemia in patients with lower risk Myelodysplastic Syndromes (MDS). These patients have shorter survival compared to patients responding to Erythropoiesis-stimulating agents (ESA), raising the question of potential negative effects of chronic RBC transfusions on MDS prognosis, independently of IPSS-R. Besides commonly identified complications of transfusions like iron toxicity or cardiac events, oxidative stress could be a risk factor for ineffective haematopoiesis. Recently, physicochemical changes of RBC during storage have been described. These changes called storage lesions could play a role in immunomodulation in vivo. We review the currently identified sources of potential impact on transfusion-associated effects in MDS patients and we discuss the unexplored potential role of erythrocyte-derived-extracellular vesicles. They could amplify impairment of haematopoiesis in addition to the negative intrinsic effects underlying the pathology in MDS. Thus, chronic RBC transfusions appear to potentially impact the outcome of MDS.

Reduction of Yersinia enterocolitica load in deliberately inoculated blood: the effects of blood prestorage temperature and WBC filtration.

BACKGROUND: Yersinia enterocolitica is known to cause severe infections in patients who receive transfusions. STUDY DESIGN AND METHODS: The aim of the study was to define the best strategy for reducing the bacterial load in blood that was deliberately contaminated with Y. enterocolitica by combining prestorage temperature and WBC filtration with conditions of blood processing close to those applied in blood banks. RESULTS: The effects of three prestorage temperatures (4 degrees C, 20 degrees C, 37 degrees C) were evaluated at various times after infection. The best reduction of bacterial load was achieved after 3 hours at 20 degrees C. In further experiments, conducted according to the former specifications, filtration of whole blood from eight and six donors with an inoculum of 100 and 500 to 1000 CFUs per mL, respectively, resulted in a total inhibition of bacterial growth up to 42 days after infection. After fractionation of blood components, in contrast to plasma and RBCs, filtration was shown to reduce dramatically the bacterial growth in buffy coats, demonstrating that the antibacterial effect of filtration was supported by the removal of infected WBCs from blood samples. CONCLUSION: These results provide support for the systematic use of blood filtration in the preparation of blood components to prevent Y. enterocolitica infection of patients receiving transfusions.