Comparable bacterial growth in platelet concentrates suspended in plasma and platelet additive solution and improved detection of bacterial contamination using a new generation automated culture system

BACKGROUND

Microbial screening of platelet concentrates (PC) with automated culture methods is widely implemented to reduce septic transfusion reactions. Herein, detection of bacterial contamination in PC was compared between units prepared in plasma and a mix of plasma and platelet additive solution (PAS) and between the BACT/ALERT 3D and next generation BACT/ALERT VIRTUO systems.

STUDY DESIGN/METHODS

Double apheresis units were split into single units, diluted in either PAS (PAS-PC) or plasma (plasma-PC), and tested for in vitro quality and sterility prior to spiking with ~30 CFU/unit of Staphylococcus epidermidis, Staphylococcus aureus, Serratia marcescens, and Klebsiella pneumoniae or ~10 CFU/mL of Cutibacterium acnes. Spiked PC were sampled for BACT/ALERT testing (36 and 48 h post-spiking) and colony counts (24, 36, and 48 h post-spiking). Times to detection (TtoD) and bacterial loads were compared between PC products and BACT/ALERT systems (N = 3).

RESULTS

Bacterial growth was similar in plasma-PC and PAS-PC. No significant differences in TtoD were observed between plasma-PC and PAS-PC at the 36-h sampling time except for S. epidermidis which grew faster in plasma-PC and C. acnes which was detected earlier in PAS-PC (p < .05). Detection of facultative bacteria was 1.3-2.2 h sooner in VIRTUO compared with 3D (p < .05) while TtoD for C. acnes was not significantly different between the two systems.

DISCUSSION

Comparable bacterial detection was observed in plasma-PC and PAS-PC with PC sampling performed at 36-h post blood collection. PC sampling at ≤36 h could result in faster detection of facultative pathogenic organisms with the VIRTUO system and improved PC safety.