Bacterial culture of platelets with the large volume delayed sampling approach: a narrative review

Bacterial contamination of platelets leading to post-transfusion sepsis (PTS) represents a significant risk to patients, even in the era of bacterial culture using a sample obtained 24 hours post-collection and inoculated into a single blood culture bottle. Various approaches are available for mitigation of this risk, one of which is large volume delayed sampling (LVDS) culture. LVDS aims to increase detection of contaminated platelets compared to 24-hour, single aerobic bottle culture by increasing the sample volume in order to inoculate two or more blood culture bottles, and increasing the delay before sampling, thus allowing additional time for bacteria present in a contaminated platelet product to multiply before sampling. Three establishments have implemented LVDS as their strategy for enhancing safety of platelets. Their collective experience points to a reduction in the residual risk of PTS following transfusion of contaminated platelets when compared to historical data. LVDS as a strategy to enhance platelet safety has the advantage of simplicity when compared to various two-step approaches that involve an early culture followed by either re-culture or rapid testing. With a seven-day shelf-life, LVDS leads to decreased platelet outdates when compared to 24-hour single bottle culture with a five-day shelf-life, and an increased age of platelets at transfusion.