title: Optimization of microbial screening for cord blood.
abstract: BACKGROUND
  Collection and processing of cord blood (CB) is associated with significant risk of contamination; hence standards mandate microbial screening of the final product. The sensitivity of current methods to evaluate the microbial content of CB is unknown, given the small volume tested and reduced sensitivity of pediatric bottles. Hence, this study was undertaken to evaluate an optimal microbial screening method.
  
  
  METHODS
  CB was collected using a closed system then spiked with organisms at 1 or 10 colony-forming units (CFUs)/mL. Samples were screened using culture bottles (BacT/ALERT, bioMérieux; and BACTEC, Becton Dickinson). Several methods were evaluated with different combinations of inoculated bottles (adult vs. pediatric), sample types (plasma discard, red blood cell [RBC] discard, or final product), and sample volumes.
  
  
  RESULTS
  Of 94 cord blood units (CBUs) spiked with organisms before screening, 81% tested positive for contamination overall. Screening of CB in pediatric bottles resulted in equivalent detection rates on the BacT/ALERT and BACTEC systems (33% at 1 CFU/mL and 73% at 10 CFUs/mL, respectively). However, the pediatric bottle screen only detected 15% of obligate anaerobes. A combined fraction method showed superior detection (71%) compared to the plasma fraction (27%) and resulted in optimal anaerobic detection.
  
  
  CONCLUSIONS
  This study demonstrates that the optimal microbial screening method for CB includes testing a combination of discard fractions (plasma and RBCs) in addition to final product using an automated culture system. Inoculating a small sample of final product in a pediatric bottle is suboptimal for microbial detection and may lead to distribution of contaminated CB for transplantation.
authors.affiliation: Sydney Cord Blood Bank, Sydney Children's Hospital, Randwick, NSW, Australia; University of New South Wales, Sydney, NSW, Australia.
authors.forename: Pamela
authors.initials: P
authors.lastname: Clark
authors.forename: Annette
authors.initials: A
authors.lastname: Trickett
authors.forename: Mel
authors.initials: M
authors.lastname: Chimenti
authors.forename: Damien
authors.initials: D
authors.lastname: Stark
mesh_terms: D001421:Bacteria, Anaerobic; D001771:Blood Banks; D004912:Erythrocytes / Q000382:microbiology; D005312:Fetal Blood / Q000382:microbiology*; D006801:Humans