Sterility Testing of Stem Cell Products by Broad-Range Bacterial 16S Ribosomal DNA Polymerase Chain Reaction

Objective: To evaluate broad-range 16S ribosomal DNA (rDNA) polymerase chain reaction (PCR) as a rapid screening tool to detect bacterial contamination of stem-cell products. Methods: We performed the evaluation using whole blood spiked with serially diluted bacterial-type strains. Detection sensitivity was defined as the bacterial concentration for which all replicates were positive at each concentration (100% detection). We tested the sterility of 29 bags of autologous peripheral blood stem cell (PBSC) products harvested at our facility using the 16S rDNA PCR method. Results: The detection sensitivity of 16S rDNA PCR in spiked whole blood was 101 to 102 colony-forming units (CFU) per mL, depending on the bacterial strain. We detected no amplified 16S rDNA among the PBSCs we used in this study. The BacT/ALERT automated bacterial culture system that we used also showed no positive signals in any of the PBSCs tested. Conclusions: Our data indicate that bacterial 16S rDNA PCR is a useful alternative for rapid sterility testing, not only for blood products used in transfusion medicine but also for stem-cell products used in regenerative medicine. * rDNA : ribosomal DNA PBSC : peripheral blood stem cell TSB : Trypticase Soy Broth SCD : Soybean-Casein Digest CFU : colonyforming units NCs : nonspiked controls UV : ultraviolet G-CSF : granulocyte–colony stimulating factor FDA : United States Food and Drug Administration