(P-BT-18) Integrating Automated Bacterial Testing into a Cellular Therapy Processing Laboratory

Traditionally, Cellular Therapy Processing Laboratories (CTPL) have relied on their institution's clinical microbiology department for automated bacterial testing. However, the unique requirements for testing Human Cell and Tissue Products (HCT/Ps) differ from regular clinical microbiology samples, necessitating an instrument optimized for these samples. These requirements include extended incubation times (e.g., 14 days instead of 5) and different incubation temperature specifications (e.g., 32.5°C instead of 37°C).

Recognizing the preferred conditions for cellular therapy product cultures, our CTPL proactively implemented an automated bacterial testing device. Currently, the initial incubation phase of testing is performed within the CTPL, and positive samples are sent to the clinical microbiology laboratory for speciation.

Study

Design/Methods:

We validated our device using several bacterial strains commonly encountered in HCT/Ps. For aerobic organisms, we chose Staphylococcus epidermidis, Bacillus subtilis, and Pseudomonas aeruginosa. For anaerobic organisms, we selected Cutibacterium acnes and Bacteroides vulgatus, and for fungal organisms, Candida albicans. The organisms were inoculated into aerobic and anaerobic bacterial bottles using 1.5 mL of sample, diluted to a final concentration of 50 colony-forming units (CFU) per bottle.

Samples 1 and 2 were fresh buffy coat samples inoculated with the organism. Sample 3 consisted of a buffy coat mixed with a cryopreservation solution containing 60% Plasmalyte, 30% HSA, and 10% Dimethyl Sulfoxide (DMSO), combined in a 1:1 ratio to a final concentration of 5% DMSO. A fourth sample, consisting of buffy coat only, was used as a control.

Results/Findings:

All organisms grew as expected, meeting the acceptance criteria for process validation (Table 1). Bacillus subtilis and Staphylococcus epidermidis grew in both aerobic and anaerobic bottles, while Pseudomonas aeruginosa grew only in the aerobic bottle. Growth was observed only in the anaerobic bottle for both anaerobes tested. Although a specific fungal culture bottle was not available, Candida albicans was detected in the aerobic bottle.

Conclusions:

Our validation demonstrated the feasibility and effectiveness of implementing an automated bacterial testing device within the CTPL. The use of aerobic, anaerobic, and fungal organisms associated with HCT/Ps, along with the inclusion of complex sample matrices containing DMSO, confirmed the device’s accuracy and reliability in detecting bacterial contamination in all product types. Additionally, since the CTPL is conducting the initial phase of bacterial testing, we ensured a streamlined and controlled testing environment, thus enhancing our laboratory's operational efficiency.