[Histonet] cleaning a cryostat after possible contamination with t.b.

Jan.Minshew <@t> leica-microsystems.com Jan.Minshew <@t> leica-microsystems.com
Tue Jan 31 14:01:52 CST 2006

Hi Sandy,

I posted this several months ago.  I hope it helps you establish a
protocol.  If you have additional questions, please feel free to contact
me.  I'll be happy to help.

Don't forget, when you have completed the disinfection protocol you must
completely dry the chamber, microtome and all accessories.  The instrument
should be lubricated according to the manufacturers specifications, using
the recommended lubricant, if it is going to be put back into service at
cold temperatures.

Whether a cryostat has a built-in disinfection system or not,
there are several very important things to remember about disinfecting
      1.  Before beginning a disinfection protocol, don personal protective
equipment (puncture and penetration resistant gloves, gowns, etc).

      2.  Remove all debris from the cryostat and disposed of it according
to the policies and procedures of your institution. The debris must be
removed because organic material (blood and proteins) may contain high
concentrations of microorganisms and could possibly inactivate chemical
germicides or prevent access to contaminated surfaces.

      3.  Use 70% ethyl (or reagent) alcohol to clean the cryostat.  The
activity of ethyl alcohol is most effective in that range and it has an
advantage over isopropyl alcohol of being able to kill hydrophilic viruses.

      4.  For those of us in the USA (other countries have access to other
products), the EPA maintains a list of Antimicrobial Chemical/Registration
Number Indexes and it is posted on their website
http://www.epa.gov/oppad001/chemregindex.htm. From this link you can find
agents effective against bloodborne pathogens such as Mycobacterium
tuberculosis, human HIV-1 virus, Hepatitis B or Hepatitis C virus. It is
critical to remember that NONE of these solutions have been tested at low
temperatures and they can only be used at room temperature.

      5.  Do not create aerosols by spraying disinfectant (or anything
else) in an open cryostat chamber.  Pour disinfectants onto absorbent
disposable towels and allow them to remain in contact with contaminated
surfaces for the length of time specified in the instructions of the
individual agents.

I hope this information is useful.  Please let me know if you have any

Best wishes to all,

Jan Minshew HT, HTL(ASCP)
Marketing Manager
Leica Microsystems, Inc.
2345 Waukegan Rd
Bannockburn, IL 60015
800.248.0123 x7051

             "Harrison, Sandra                                             
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             Sent by:                                                   cc 
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             ern.edu                   [Histonet] cleaning a cryostat      
                                       after possible contamination with   
             01/31/2006 01:27                                              

Dear Histonetters,

I've checked with numerous other labs, also with CAP, to try to
determine the best method for decontaminating a cryostat after a
specimen has been cut on it that might be t.b.

Almost everyone agrees that the cryostat needs to be shut down, brought
to room temp, and exposed to a disinfectant.  The variations seem to be
in which disinfectant.

Some use 37% formalin in an open container placed in the cryostat,
allowing it to remain in there overnight so that the cryostat is exposed
to the fumes.  Then the interior is wiped down with absolute alcohol.
After 24-48 hours, to ensure complete dryness, the cryostat is turned
back on.

Some people use a liquid phenolic, rather than formalin fumes and then
absolute alcohol.

The downside of using the formalin fumes is that some have reported
pitting in the cryostats interior.

Of course, the best of all would be to have one of the self
de-contaminating cryostats which use either ultra-violet light or have a
well for the 37% formalin and is an automatic cycle.

Please tell me what methods YOU are finding best and why.



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