Is the Stella™ 5L system an effective cold sterilization technique for needle-based confocal miniprobes?

Needle-based confocal laser endomicroscopy (nCLE) under endoscopic ultrasound guidance is a newly developed imaging technique for pancreatic lesions and lymph nodes, enabling a subcellular level of resolution. The confocal miniprobe is an invasive instrument designed to be reused up to 10 times. Therefore, a method that ensures the complete elimination of microbial contaminants on the device is necessary. We studied the bactericidal efficacy of the Stella™ system, which purports to achieve this objective.

The surfaces of three nCLE miniprobes were contaminated with suspensions of Bacillus atrophaeus (ATCC9372). One probe was randomly selected to count the bacterial load on the surface. The other two probes were manually cleaned and rinsed. One probe was randomly selected to count bacteria on the surface, and the other probe was sterilized using the Stella™ 5L endoscopic sterilization system before obtaining the bacterial count. The process was repeated for 20 cycles to evaluate the microbicidal efficacy of the Stella™ 5L endoscopic sterilization system. These miniprobes were immersed in the Stella Fuse disinfectant for 72 h. After the 72 h of immersion, the weight loss of probes was determined using a high precision electronic scale to examine corrosion following disinfection. The change in image quality was evaluated by an endoscopist.

From an initial contamination level of 4.48 × 106 ± 1.57 × 106 cfu/mL on the surface of the probes, the bacterial count was reduced to 4.25 × 102 ± 1.95 × 102 cfu/mL after manual cleaning (including enzyme washing), and no microorganisms were recovered after 20 cycles with the Stella™ 5L system. The probe weights before and after 72 h of immersion were 45.769 (45.768-45.771) g and 45.762 (45.752-45.768) g, respectively. No change in image quality was observed.

This study shows that the Stella™ 5L system is capable of the complete elimination of microorganism contamination in a short period and avoids the toxicity of typical disinfectants. It is a safe, cheap, and efficient sterilization approach that provides a new option for nCLE miniprobe sterilization.