Sterility release testing of peripheral blood stem cells for transplantation: impact of culture bottles and incubation temperature

Abstract

Sterility testing of peripheral blood stem cells (PBSCs) is mandatory before release. As antibiotic treatment of the PBSC donor may result in false-negative results, PBSC matrix validation must be carried out. Three spiked PBSCs and a buffy coat (BC; control matrix) were analyzed using the blood culture device BacT/ALERT 3D with the low-temperature module. Samples were spiked with Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Candida albicans, Aspergillus brasiliensis, Clostridium sporogenes, and Propionibacterium acnes. Standard iAST/iNST culture bottles and iFA/iFN Plus bottles, which include resorbing polymers, were incubated for 14 days. All aerobic bottles were incubated at 22.5°C and for a direct comparison also at 35°C while all anaerobic bottles were incubated at 35°C. The BacT/ALERT 3D system detected all microbes in iAST/iNST culture bottles according to their growth behavior in the BC matrix. Detection of microbes differed significantly in PBSC products using standard iAST/iNST culture bottles and iFA/iFN Plus bottles with resorbing polymers: In Graft 1 no growth was detected in spiked bottles with S. aureus (iAST), B. subtilis (iAST/iNST), C. sporogenes (iNST), and P. acnes (iNST) compared to iFA Plus and iFN Plus bottles wherein growth of spiked microbes was confirmed. Graft 2, with another antibiotic treatment, showed no growth in iAST/iNST bottles spiked with P. aeruginosa, B. subtilis, and C. sporogenes. However, using iFA/iFN Plus bottles all spiked microbes were detectable. The comparison of incubation temperature showed an expected slower growth at 22.5°C. The use of iFA/iFN Plus culture bottles incubated at different temperatures safely detected microbes in spiked PBSCs.