Increased frequency of false-positive bacterial detection after implementation of new guidelines for large-volume delayed sampling of platelets.

BACKGROUND: The updated guidance for improving bacterial detection (BD) of platelets has included the implementation of large-volume delayed sampling (LVDS) with the addition of anaerobic culture bottles (BPNs) and sampling of each platelet split product.

METHODS: The frequency of BD was reviewed during this LVDS time period in comparison with pre-LVDS and the Post-Approval Surveillance Study of Platelet Outcomes, Release Tested (PASSPORT) study (when BPNs were last used).

RESULTS: There was more than a twofold increase in bottles inoculated per collection during LVDS, with an almost fivefold increase in sample volume collected. During LVDS, the concordance of split products within an initial reactive collection was only 8.7%. There was no difference in LVDS aerobic culture bottle (BPA) true positives (TPs), but there was a significant increase in LVDS false positives (FPs), p < .0001, compared to both PASSPORT and pre-LVDS, respectively. There was an increase in BPN TPs during LVDS (p < .05 compared to PASSPORT), with predominance of Cutibacter acnes (C. acnes), noted exclusively in BPN, and accounting for more than two-fifths of all organisms detected. Time to alarm during LVDS for TPs had two peaks with one due to C. acnes at 96 h compared to 17 h for non-C. acnes.

DISCUSSION: The high FP frequency, along with low clinical significance of TPs found in BPNs, has led to the needless discard of inventory, as the utility of BPNs in BD for platelets is yet to be established and may require much larger studies.