Evaluation of Tissue-C and CorneaMax organ culture media for microbial contamination detection in corneal grafts using the BD BACTEC FX system

Corneal grafting requires reliable organ culture conditions and robust microbiological monitoring. CorneaMax (Eurobio) and Tissue-C (Alchimia) are widely used in European eye banks, but the CE certification of CorneaMax was recently discontinued, prompting a transition to alternative media. This study assesses the performance of the BD BACTEC FX system in detecting microbial contamination in Tissue-C compared with CorneaMax, following European Pharmacopoeia standards. The organ culture media were inoculated with ten microorganisms in compliance with the European Pharmacopoeia, 10.5th edition. Different volumes (10, 1 or 0,2 mL) were inoculated into four BD BACTEC blood culture bottles, including Plus Aerobic/F, Lytic Anaerobic/F, Mycosis IC/F, and Plus Anaerobic/F (Becton Dickinson). Using a 10-mL volume the sensitivity of microorganism detection across the four bottle types was 93.3% for CorneaMax and 66.7% for Tissue-C. Reducing the volume to 1 mL increased the sensitivity to 100% for CorneaMax and 80% for Tissue-C, although S. pyogenes and C. acnes remained undetected in Tissue-C. Further decreasing the volume to 200 µL ensured consistent detection of both species across three replicates. Interestingly, Tissue-C exhibited higher antibiotic activity than CorneaMax, likely explaining the reduced sensitivity of the method with Tissue-C compared to CorneaMax. Moreover, resin-free Lytic Anaerobic/F bottle provided no added value at any inoculation volume. This study demonstrates that microbiological monitoring of corneal grafts must be tailored to the culture medium. CorneaMax provides reliable detection with three BD BACTEC bottles, whereas Tissue-C, due to its higher antibiotic activity, requires further optimization of the monitoring strategy.