P64 NHS Cord Blood Bank: Microbiological Screening Results of Cord Blood Donations

Abstract

Following the world's first umbilical cord blood transplant performed by Gluckman et al in 1988, the NHS Cord Blood Bank (NHS‐CBB) was established in 1996 with the primary aim to redress the ethnic imbalance of donors represented on the British Bone Marrow Registry. The NHS‐CBB collects cord blood following delivery of the placenta at a stage where it is considered a waste product. This allows thorough decontamination of the umbilical cord prior to venepuncture. All processing is performed in a closed system or in a cleanroom environment. Microbiological screening of all cord blood units is performed on the final product for aerobic, anaerobic and fungal contaminants, prior to cryopreservation. Contamination rate for the first year of banking was 10.5%. This high rate initiated development and validation of a new cleaning protocol in conjunction with the National Bacteriology Laboratory (NBL). Following the introduction of this system in March 1997 contamination rates subsequently decreased to a median 0.8%. Species identification has elucidated that 54.4% of contaminants were skin flora. Regular quality monitoring of collection and processing indicates that the major source of contamination is at collection. In comparison, contamination of red blood cell collections within the NBS has been found to be approximately 0.08%. This difference may be explained by the inherent difficulties in decontaminating an entire umbilical cord attached to the suspended placenta, use of a wider bore needle and inclusion of the umbilical cord core sample into the collection bag. The NHS‐CBB has issued three bacteriology positive units for transplantation (2.4% of total units issued) with no adverse events reported. In line with current international cord blood banking standards, the CBB now discards all microbial positive donations. Collaboration with the NBL enables the CBB to monitor contamination rates, minimise contamination, thereby maximising efficiency and reduction of wastage.