TRANSPLANTATION AND CELLULAR ENGINEERING
Sterility testing of minimally manipulated cord blood products: validation of growth-based automated culture systems
The St Louis Cord Blood Bank submitted a biologics license application for cord blood (CB) products processed by PrepaCyte-CB (BioE), supported with a validation study of a microbial detection system for product sterility testing (BACTEC-FX, Becton Dickinson). This article provides the validation approach followed to fulfill Food and Drug Administration requirements pertinent to sterility testing method.
Study Design and Methods
System qualification, culture media quality verification, and validation of CB processing by-product (CB-BP) sample as surrogate to final product for sterility testing were followed by studies evaluating method sensitivity, specificity, reproducibility, ruggedness or robustness, and bacteriostatic or fungistatic effect of CB-BP sample. CB-BP cultures and control samples were formulated using BACTEC Plus Aerobic/F, Plus Anaerobic/F, and Myco F/Lytic media. Samples were seeded with selected test organisms (n = 13 at 10-100 colony-forming units [CFUs] per vial) and cultured for 14 days (bacterial) and 30 days (fungal).
Under testing conditions, no stasis effect of test sample on microbial growth and no false-positive or false-negative results were reported. Although a 7-day culture was sufficient to detect all validation test organisms seeded at ≤26 CFUs/vial, growth in actual product sterility testing practice may require a 10- to 14-day culture. Assay reproducibility was uncertain at very low bioburden (<10 CFUs/vial). Growth time to detection neither varied between different media lots nor prolonged in culture vials with loading delay (6-8 hr at room temperature).
BACTEC-FX culture and detection system and BACTEC media formulae have high detection capability and can be effectively validated for sterility testing of CB products.