New strategies for bacterial contaminations

Abstract

Background The detection of bacterial contaminations in blood components can be classified in culture methods, rapid detection methods and experimental new technologies. Culture methods Culture methods have shown their benefit through easy handling and high analytic sensitivity. The challenge with culture methods, with the negative‐to‐date release concept, is a risk for false negative screening results due to sample failures and a reduced clinical efficiency. Rapid detection methods Within the last decade, rapid bacterial detection systems (RBDS) were developed as an alternative option to culture systems. In RBDS, testing time is reduced to 2–3 h. Therefore, a negative‐to‐date release concept is not necessary using these systems. New technologies In addition, new technologies are currently in development to detect bacterial strains in blood components. Electrochemical biosensors were developed for many different analytes, which range in size from individual ions and small molecules to nucleic acids and proteins up to whole viruses and bacteria. Conclusions Bacterial detection in blood components, especially in platelets, is implemented in many blood donor services. New approaches are promising to come to a next level to be implemented into routine screening, but the analytical sensitivity has to be improved for some of the new test systems in the coming years. Due to the fact that a risk for bacterial contamination still occurs in all blood components, the focus in transfusion medicine in the next decade will be the development of general principles and strategies to detect or inactivate bacteria in all blood components. Therefore, new developments are gladly welcome.

Combining culture and microbead‐based immunoassay for the early and generic detection of bacteria in platelet concentrates

“…The disadvantages of these methods are the risk of sampling errors and false‐negative results, despite the high sensitivity, especially for slow‐growing bacteria and bacteria‐forming aggregates in platelet concentrates . Products tested by culture‐based methods with continuous monitoring are distributed as “negative‐to‐date.” Indeed, 30% to 50% of tested platelet concentrates are transfused before a positive signal occurs . To overcome this issue, secondary rapid or culture testing using devices approved by the FDA is recommended on Days 4 and 5 after collection as a safety measure .…”

“…Prevention of transfusion‐transmitted infections is one of the major goals in transfusion medicine. The residual risk of transmitting the major viruses hepatitis C virus, hepatitis B virus, and human immunodeficiency virus has been reduced to a minimum using nucleic amplification technologies and fourth‐generation serology screening tests . In the period 2010 to 2013, among the 96,798,000 blood components distributed, the European commission reported 111 transfusion‐transmitted infections in the European Union, including 73 bacterial (66%), 35 viral (32%), and 3 parasitic cases (<3%) .…”

“…In the period 2010 to 2013, among the 96,798,000 blood components distributed, the European commission reported 111 transfusion‐transmitted infections in the European Union, including 73 bacterial (66%), 35 viral (32%), and 3 parasitic cases (<3%) . Bacterial contamination remains the highest residual infectious risk despite current preventive strategies …”

“…Products are tested with continuous monitoring and are distributed as “negative‐to‐date” based on the status of the culture at the time the unit is released . As an alternative option, rapid bacterial detection systems with a testing time reduced to 1 to 3 hours have been developed . Some of these systems, based on the fluorescence‐activated cell sorting method, nucleic acid testing within the ribosomal bacterial genes, or portable assays, have been reported by several groups.…”

“…A large diversity of species is found in contaminated platelets, which represents a key challenge for the development of a generic bacterial detection test. Contamination of platelets with gram‐negative organisms, although less common than gram‐positive organisms, is more likely to result in clinically significant reactions . Moreover, the immune status of the recipient will determine the level of severity of the reaction, which can range from minor symptoms to life‐threatening sepsis or even death.…”