New approaches to disinfection of thermolabile medical devices using an indirect method with cold atmospheric plasma-aerosol

Cold atmospheric plasma-aerosol (CAP-A) offers a promising alternative to conventional sterilisation and disinfection methods, which are often unsuitable for thermolabile medical devices due to high temperatures, toxic chemicals or radiation. CAP-A efficiently inactivates microorganisms and viruses without compromising the material integrity. Given the ongoing risk of infection associated with ultrasound probes and other delicate diagnostic instruments, this study investigates whether an indirect CAP-A method can meet all requirements for effective and safe disinfection of thermolabile medical devices. The disinfection of thermolabile medical devices was carried out in a container saturated with indirect CAP-A. A transvaginal ultrasound probe was used as a reference product. The study involved six test organisms, with five measurements taken at six different measurement points. The study showed that Enterococcus hirae (mean logarithmic reduction factor (LRF) > 6.23), Staphylococcus aureus (mean LRF > 6.51), and Enterococcus faecium (mean LRF > 6.16) demonstrated a germ reduction of > 99.9999%. For Pseudomonas aeruginosa (mean LRF > 5.40) and Escherichia coli (mean LRF > 5.29), a germ reduction of > 99.999% was achieved, and for Candida albicans (mean LRF > 4.95) and Clostridioides difficile (mean LRF > 4.62), a germ reduction of > 99.99% was demonstrated. The log reduction demonstrates a complete inactivation of the six tested microorganisms. The initially defined requirements for an effective disinfection process for thermolabile medical devices were met in the CAP-A method. Regarding highly tenacious microorganisms, such as Clostridioides difficile, the method of CAP-A proved effective, superior to alcohol-based methods, and with no resistance development observed. Its efficacy is otherwise only known in corrosive chemicals, such as hydrogen peroxide, chlorine, and chlorine dioxide. However, these chemicals have corrosive-oxidative effects on the surfaces to be disinfected and are critical in terms of market launch and hazardous material classification. Therefore, the method of CAP-A, provides an effective, material-friendly alternative.