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Final disinfection (High Level Disinfection) of semi-critical medical devices - which spectrum?

Updated: Sep 11, 2023

Semicritical medical devices are medical devices that, by definition, may come into contact with healthy mucosa or abnormal skin (Spaulding Classification; Spaulding EH. Chemical disinfection and antisepsis in the hospital. J Hosp Res, 9:5-31, 1972). They do not have to be sterile after reprocessing, since they are not used in sterile areas of the body, but of course they must not pose a risk of infection. Since sterilization is not required in this case, particularly high requirements are placed on disinfection here.

The disinfection process, whether manual or mechanical, must be able to kill bacteria including mycobacteria, fungi and fungal spores as well as inactivate viruses. I.e. it must be bactericidal, mycobactericidal, fungicidal and virucidal. The disinfectant used should also have the potential to kill bacterial spores. In Europe, the standards of CEN/ TC 216, which are described in the current version of EN 14885, are used to demonstrate effectiveness.

This high level disinfection can therefore only be carried out using certain types of active ingredients. These are primarily aldehydes and oxidizing substances such as peracetic acid or hydrogen peroxide. It is also important when using High Level Disinfection that the medical device is not contaminated again after disinfection by the obligatory post-rinse step.

Therefore, it is essential to pay attention to the microbiological quality of the post-rinse water. Preferably, the post-rinse water should be sterile.

About the author

Verona Schmidt has been a member of AKI from 2002-2022 and represented the manufacturers of process chemicals in the group. As a microbiologist at Chem. Fabrik Dr. Weigert in Hamburg, she is responsible for the area of microbiology and hygiene and, in this context, deals with efficacy testing of disinfectants. She also participates in several standardization committees of CEN TC 216 "Chemical disinfectants and antiseptics" in the development of European standards for testing disinfectants.

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