Re: using 100% as decontaminant in cryostat

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From:Steve & Linda Roggy <>
To:Gayle Callis <>
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Hi all!

When we have to decontaminate a cryostat - first throw away the blade. Then we
spray the inside of the unit with Cavicide, let it defrost and spray again (using
appropriate aerosol protection). Remove the microtome unit, take it apart, clean as
thoroughly as possible with absolute, then submerge the unit in absolute. Allow the
unit to air dry, re-lubricate. The chamber has been wiped out with cavicide (or
whatever disinfectant currently available that is anti-bacterial, etc.), wipe off
with absolute. Run Cavicide through the drainage system until fluid is clear.  I
don't think that absolute is classified as a disinfectant/antimicrobial agent.
Allow everything to dry.  Reassemble cryostat. All swabs, gauze, towels, etc. used
while cleaning are biohazard discards - we wear biohazard gowns, masks and gloves
when decomtaninating. AFB lives long and does prosper.  All of this only takes
about an hour to do - the drying of the microtome after the absolute is the longest
period.  We are required to wear gloves when doing frozens (hospital setting here),
and a TB respirator when doing frozens that are highly suspect of TB or HIV. We
usually have to decontaminate a cryostat at least once a week. Keeping the cryostat
as litter free a possible between frozens goes a long way to speed up the regular
cleaning and the decontamination procedure.

Linda Roggy
Greenville Memorial Hospital

Gayle Callis wrote:

> I think the use of alcohol was discussed eons ago, as a decontaminating agent
> in cryostat.  The question arose, 70% vs 95 or absolute alcohol, and 70% was
> preferred for specific reasons, had something to do with suface tensions, etc.
> hopefully someone will come forth with this again.
> Afer observing people inside of biohoods, cleaning down an area (wiping),
> they use 70% ethanol to reduce contamination by bacteria and some are working
> with adenoviruses.  I figured if they get no contamination of their cell
> cultures, etc, with this type of cleaning, it would work in the cryostat as
> well.
> To decontaminate, we defrost, wipe down with 70% several times on absorbant
> towels, go to 100% to remove the residual water (cryostat is supposed to be dry
> before putting it back together)  There are some wipe cloths available now,
> from Current Technology that look promising, if people want to do a final
> wipedown after the 70% or even before that (when cryostat is warmed from
> defrosting).  There are other sources of wipe cloths, but I was always afraid
> to put too much gunk in the cryostat, didn't want corrosion.
> We do wipe down areas in cryostat when it is running with 70% also, not a lot,
> but enough to attract all the trimmings and after every use, if necessary.
> I think this in one of the tough areas to deal with, cryostat innards and
> protecting workers, and using formalin fumes just isn't acceptable.
> Out of curiosity, does everyone cryosection with gloves on these days in the
> clinical setting?
> Gayle Callis

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