Experimental contamination assessment of a novel closed ultravitrification device

Objective: To evaluate the safety of a new ultravitrification closed device. Design: Ultravitrification research. Setting: Private assisted reproduction center. Animal(s): Microorganisms (bacteria). Intervention(s): A styrofoam container holding 1,000 mL of liquid nitrogen (LN2) was contaminated with Pseudomonas aeruginosa and Escherichia coli. Forty closed devices (Ultravit) and 20 open devices (Cryotop) loading approximately 0.5 μL of antibiotic-free medium were plunged into this contaminated LN2 for 5-10 seconds and then inoculated into selective culture dishes. Colony-forming units were analyzed and counted after an overnight incubation at 37°C. Main Outcome Measure(s): Detection of micro-organisms in different devices after incubation. Result(s): There was no contamination in any of the closed devices, whereas in 45% of open devices these bacteria were present. Conclusion(s): With this study we demonstrated, in an experimental model using contaminated LN2, that this new closed device is a safe system that does not allow cell contact with LN2, avoiding cell contamination.