Comparison of different methods of bacterial detection in blood components

Abstract

Background Over the last two decades, the residual risk of acquiring a transfusiontransmitted viral infection has been reduced to less than 1 : 1 000 000 via improvements in different techniques (e.g. donor selection, leuco-depletion, introduction of 3rd or 4th generation enzyme-linked immunosorbent assays and mini-pool nucleic acid testing (MP-NAT). In contrast, the risk for transfusion-associated bacterial infections has remained fairly stable, and is estimated to be in a range between 1 : 2000 and 1 : 3000. Platelets are at an especially higher risk for bacterial contamination, because they are stored at room temperature, which provides good culture conditions for a broad range of bacterial strains. To improve bacterial safety of blood products, different detection systems have been developed that can be divided into culture systems like BacT/ALERT or Pall eBDS, rapid detection systems like NAT systems, immunoassays and systems based on the FACS technique. Culture systems are used for routine bacterial screening of platelets in many countries, whereas rapid detection systems so far are mainly used in experimental spiking studies. Nevertheless, pathogen-reduction systems are currently available for platelet concentrates and plasma, and are under investigation for erythrocytes. MethodsIn this review, the functional principles of the different assays are described and discussed with regard to their analytical sensitivity, analytical specificity, diagnostic sensitivity, diagnostic specificity and clinical efficiency. The detection methods were clustered into three groups: (i) detection systems currently used for routine screening of blood products, (ii) experimental detection systems ready to use for routine screening of blood products, and (iii) new experimental detection systems that need to be investigated in additional spiking studies and clinical trials.Results A recent International Society of Blood Transfusion international forum reported on bacterial detection methods in 12 countries. Eight countries have implemented BacT/ALERT into blood donor screening, whereas in three countries only quality controls were done by culture methods. In one country, shelf-life was reduced to 3 days, so no bacterial screening was implemented. Screening data with culture methods can be used to investigate the prevalence of bacterial contamination in platelets. Differing results between the countries could be explained by different test definitions and different test strategies. Nevertheless, false-negative results causing severe transfusion-related septic reactions have been reported all over the world due to a residual risk of sample errors. Rapid screening systems NAT and FACS assays have improved over the last few years and are now ready to be implemented in routine screening. Non-specific amplification in NAT can be prevented by pre-treatment with Sau3AI, filtration of NAT reagents, or reduction of the number of polymerase chain Bacterial detection in blood components 81 reaction cycles. FACS systems offer easy fully aut...

Bacterial contamination in platelets: incremental improvements drive down but do not eliminate risk

“…Improvements in donor selection and testing have reduced the risk of acquiring a transfusion‐transmitted viral infection, such as human immunodeficiency virus, to less than 1 in 1,000,000 1 . The risk of acquiring a bacterial infection from a blood transfusion remains significantly higher 2,3 . Unlike other blood components that are cold stored, platelet components (PCs) are stored at 20 to 24°C, providing hospitable growth conditions for many bacterial species and increasing the risk of bacterial contamination for these components.…”

“…A key element in reducing transfusion of bacterially contaminated PCs is effective detection of contaminated components in the event that preventative measures fail 3 . There are several obstacles to the successful identification of bacterially contaminated PCs.…”

Bacterial skin flora and contamination of blood components: do we defer blood donors wisely?

“…Contamination of blood products with bacteria is a well known risk, and has been targeted with different approaches: prospective routine culture of all platelet products, shortening of shelf life to three days, and pathogen reduction techniques. According to an international blood banking forum, all participants had introduced at least one step into their processes to enhance bacterial safety [30, 31].…”

Reasons for moving toward a patient‐centric paradigm of clinical transfusion medicine practice

“…Furthermore, regardless of whether old RBCs are associated (or not) with the debated “common” adverse effects of old blood (increased mortality, postoperative infection, and/or multiple‐organ failure), 10‐13 old RBCs are an inferior‐quality product from the vantage point of laboratory variables (e.g., the proportion of transfused stored RBCs surviving in the circulation at 24 hr after transfusion and the corresponding ability of the transfused component to deliver oxygen to tissues). Similarly to old RBCs, old PLTs (stored for 4 or 5 days) have a higher risk of TAS 14,15 than fresh PLTs and prolonged PLT storage periods in PLT additive solution (AS) II are also associated with lower posttransfusion corrected count increments 16 …”