Reducing the Risk

Reducing Bacterial Contamination Risk of Platelet Components with Pathogen Reduction

Dr. Richard J. Benjamin, chief medical officer at the American Red Cross for over ten years and currently holding the same position at Cerus, points out that much of the literature indicates that the discrepancy in sepsis and fatality rates between countries with active and passive haemovigilance suggests that the latter leads to underreporting of severe reactions and under-recognition of adverse events.

Active surveillance, culturing each unit of platelets when issued to patients, shows about a 40-fold higher rate of detection of contamination and a 10-fold higher rate of sepsis.[1] Passive surveillance relies on reporting by the treating physicians. As a reaction may occur hours after the transfusion, physicians don’t always make the connection and therefore don’t recognise the signs and symptoms of sepsis, especially as many clinicians have developed a false idea of total safety when it comes to blood. The US Food and Drug Administration recognises this flaw in current blood safety measures, and issued draft guidelines proposing either pathogen reduction (PR) or secondary testing, the latter requiring a culture system in the blood centre plus a point-of-issue test in the hospital. Dr. Benjamin considers PR to be the more complete and cost-effective solution. He believes PR offers peace of mind when it comes to bacteria, provided it’s done within recommended time limits and with an efficient PR technology.

Contamination of the platelet product occurs at collection. Initial contamination tends to be very low, but may multiply to dangerously high levels in a very short time. To avoid reaching bacterial concentrations that would be able to harm a patient, it is recommended that the procedure be performed as soon as possible after collection. Whether platelets are collected by means of whole blood or apheresis plays a role in the time intervals between collection and reduction, which testing showed to be within the safety margin. The INTERCEPT^TM Blood System for platelets leaves a window of 24 hours offering absolute safety to treat apheresis platelets. Laboratory tests have shown that a delay of up to 30 hours, occasional breakthroughs with very high inital numbers of bacteria present were observed.[2] Whole blood platelets allow for a longer time span, the buffy coat pooling to be done within 23.5 hours and the consecutive PR treatment within 12 hours. Exceeding these recommendations gradually increases the risk of occasional bacterial breakthroughs.

Not all PR technologies on the market offer the same performance. Killing 99.9% of the bacteria in a bag is simply not good enough. Even a small number of viable bacteria may grow back and reach concentrations sufficient to kill a patient within one or two days. Therefore, any blood centre or hospital considering the implementation of a PR technology needs to validate the robustness of the system. The safety margins mentioned make the INTERCEPT system very robust and consequently very suitable to support different operational processes.