Fixation on Histology

You always want to ensure that the equipment you are using is clean, but how often should you clean when time constraints are another pressing factor? It can seem like taking a cryostat down to room temperature for disinfecting will throw a wrench in the workflow of a busy frozen sectioning room, but it is in fact essential.

When it comes to cryostats, the CAP Laboratory Accreditation Program checklist requires that “the cryostat must be defrosted and decontaminated with a tuberculocidal disinfectant at an interval appropriate for the institution; this must be weekly for instruments used daily”. (ANP. 12087 Phase II revised 06/15/2009)

Many laboratories will use UV light to decontaminate their cryostats. While this is a good aid for decontamination, it will only decontaminate the areas that the light touches, so for full decontamination, especially in suspected TB cases, it is essential to defrost the cryostat and use a tuberculocidal disinfectant.

So, what is a tuberculocidal disinfectant? Firstly, it must be registered with the EPA, the regulatory body for disinfectants. The EPA has a list of approved disinfectants, noted as effective against common pathogens.

Before using these disinfectants, or UV light, it is also essential per the CAP checklist regulations, that “Trimmings and sections of tissue that accumulate inside the cryostat must be removed”. These bits can get in the way of the light reaching the surface and can contain high concentrations of microorganisms.

When preparing for CAP inspection, make sure your lab has a procedure for routine decontamination of cryostats, and that you have record of this decontamination procedure.

References:

http://webapps.cap.org/apps/docs/education/OnlineCourseContent/2011/LAP/Resources/Checklists/AP.pdf

https://www.avantik-us.com/content/disinfection-for-cryostats.asp

https://www.epa.gov/sites/production/files/2016-12/documents/list_b_tuberculocide.pdf

http://demo.nextlab.ir/getattachment/4f9a710b-de4a-42aa-b7c4-816ace9dada8/CLSI-M29-A3.aspx

http://grossing-technology.com/prevention-of-infection-exposure-during-frozen-section/

https://www.nsh.org/communities/community-home/digestviewer/viewthread?MessageKey=09587239-3467-4368-AF30-3C7B69815104

https://www.leicabiosystems.com/pathologyleaders/reduced-infection-risk-uvc-disinfection-effective-for-destroying-clinically-relevant-pathogens/