Persistence of Staphylococcus epidermidis in Cardiopulmonary Bypass Circuits Primed with Plasma-Lyte A: Implications for Circuit Storage Following Contamination

Background There is limited evidence on how long cardiopulmonary bypass (CPB) circuits can remain primed before use or when primed CPB circuits should be disposed of due to loss of sterility or instability of the priming solution. Understanding bacterial persistence in priming solutions is critical for patient safety and institutional protocols. This pilot study aimed to evaluate the survival of Staphylococcus epidermidis in Plasma-Lyte A-primed CPB circuits over time. Methods Three commercially available CPB circuits (Affinity, CAPIOX, and Inspire) from different manufacturers (Medtronic, Terumo, and LivaNova) were primed with Plasma-Lyte A inoculated with S. epidermidis (~1 CFU/mL) to simulate accidental contamination. Following brief recirculation, circuits were stored without circulation at 20–22°C. Samples were obtained aseptically from pre- and post-oxygenator sites on Days 0, 2, 4, 7, 9, and 11. Viable bacterial recovery was reported as colony-forming units per milliliter (CFU/mL) over time. Results Viable S. epidermidis was recovered from all three CPB circuits at both sampling sites through Day 11. Colony counts remained low, fluctuating between approximately 1 and 9 CFU/mL without a consistent increase over time. The highest observed count, 9 CFU/mL, occurred at the Inspire post-oxygenator sampling site on Day 7. Each measurement represented a single observation. Conclusion Viable S. epidermidis remained detectable at low levels in intentionally contaminated Plasma-Lyte A–primed CPB circuits over 11 days. These findings suggest that primed circuits may permit prolonged bacterial persistence, raising concerns about potential patient exposure if contaminated circuits are used. This pilot study reinforces the importance of strict aseptic technique, careful consideration of storage duration, and appropriate institutional protocols for circuit management and microbial monitoring. Thesefindings may inform handling of preassembled, customized circuits tailored to institutional needs. Larger, replicated studies with appropriate controls are needed to characterize bacterial persistence and establish evidence-based guidance for primed circuit storage.