I haven't read the article, so read this with that fact in mind.

When I trained in the 1960s TB was fairly common still.  We were taught 
to handle TB infected tissues relatively safely.  However, looking back 
on it we were quite lax compared to today's attitudes towards safety in 
lab work.

There were some things we did that were more likely to protect us than 
are done today, though.  One of the most important is the duration of 
fixation with formalin mixtures.  We used to fix a minimum of overnight, 
sometimes up to a couple of weeks, mostly because there was no fixation 
(pun intended) on a 24 hour diagnosis.  Even then it was known that TB 
organisms resisted formalin fixation, so known cases were routinely left 
for a few days before grossing.  Often they would be refixed after that. 
  The usual approach was to expose the organisms to a minimum of 48 
hours in formalin, with a week being better.  After that they were 
presumed to be safe.

It should be kept in mind, though, that in the past we used longer 
processing schedules with quite a bit longer in ethanol and xylene.  It 
was presumed (no proof) that the fat solvent nature of those affected 
any remaining viability of TB organisms by dissolving out the mycolic 
acid coat.  At any rate, with older long fixation and slow processing we 
considered the organisms to be dead.

Today, short fixation and fast processing is the norm so I would suggest 
that should no longer be considered true, and that you are indeed at 
risk.  On the plus side, modern processors do use heat during 
processing, and cassettes limit the thickness of the tissue, so they are 
  less likely to come out unprocessed than they were in the past.

Since TB is on the rise again I think the whole subject should be 
reappraised and standard safe working protocols publicised and enforced. 
  I stress the "enforced" since we all know that protocols are 
established  and may then be completely ignored because they are 
inconvenient.  This comes through very clearly with some of the comments 
about the (US) CAP inspections on Histonet.  We have similar inspections 
in BC, Canada with similar attitudes, I might add, and I presume other 
countries are the same.

Before I retired I had a long term disagreement with our safety 
committee and lab administration regarding this issue.  The lab wanted a 
24 hour turnaround time, while the safety committee wanted all lab 
departments to work with universal precautions, that is, treat all 
specimens as if they are infected with the worst possible organism.  I 
repeatedly pointed out that these were mutually exclusive for TB, HIV, 
hepatitis and other things.  For universal precautions we would have had 
to fix all biopsies for 2-3 days before processing just in case a 
formalin resistant organism was involved.  That would preclude a 24 hour 
diagnosis.  I was never able to get an answer to my objections on this 
issue, and I consider it to be an area of administrative hypocrisy.  I 
did, however, make sure my comments were clearly recorded just in case 
of a WCB claim by one of the technologists.

The reality is that we are expected to section and stain tissues that 
are infected and which may well contain viable organisms.  In practice, 
the issue then becomes how to do this and work safely.  I suggest that 
the following should form the basis.

1.  Get vaccinated for everything you can.  This should be at employer's 
expense.  If they refuse to pay, get it done, pay yourself and then kick 
up one hell of a fuss.
2.  Wash your hands frequently.  Use soap and hot water and maybe a 
brush.  Be thorough, not cursory.  This helps with squame contamination 
on sections, too.  Don't forget the face, especially around the mouth 
and nose.  We frequently touch those areas without being aware of it.
3.  Wear gloves.  Don't presume this means you need not wash your hands.
4.  Wear masks.
5.  NEVER cut frozen sections on unfixed TB, HIV or hepatitis cases, ever.
6.  Fix tissues as long as possible as a routine.
7.  Use as long a processing schedule as you can get away with.
8.  NEVER process known TB, HIV or hepatitis tissues with less than 48 
hours fixation.
9.  Sacrilege.  Put your own health before that of the patients.  You 
won't do anybody any good lying in a hospital bed.  Do NOT fall into the 
trap of making an exception because "the patient needs a diagnosis". 
Usually that means someone else can't be bothered to wait.
10. Make a nuisance of yourself with any committees or groups that have 
influence in these areas, and don't stop.

This is not exhaustive by any means, and like Patsy, I would like to see 
this issue discussed far more thoroughly.

Bryan Llewellyn




Patsy Ruegg wrote:
> This is alarming.  I have not been on histonet for a while, was there
> responses to this?  I have been working with formalin fixed paraffin
> embedded tb infected tissue for years without using these kind of
> precautions.  Am I at risk for TB infection?
> Patsy Ruegg
> 
> -----Original Message-----
> From: Patsy Ruegg [mailto:pruegg@ihctech.net]
> Sent: Saturday, August 28, 2004 9:51 AM
> To: pruegg@ihctech.net
> Subject: FW: [Histonet] TB in Lung Specimens
> 
> 
> 
> 
> -----Original Message-----
> From: histonet-bounces@lists.utsouthwestern.edu
> [mailto:histonet-bounces@lists.utsouthwestern.edu]On Behalf Of Andrew
> Kennedy
> Sent: Monday, August 09, 2004 2:19 PM
> To: Histonet
> Subject: [Histonet] TB in Lung Specimens
> 
> 
> Hi Histonetters,
> 
> 
> 
> A recent article in Human Pathology suggests that Mycobacteria in formalin
> fixed tissue can remain viable and therefore there is a risk of contracting
> TB from these specimens. It suggests that formalin fixed tissue from
> suspected TB cases should be handled with gloves, gown and mask.
> 
> 
> I wonder if we should be using these precautions for every lung specimen at
> every step in the histological process! If the organisms are still viable,
> trimmings from blocks should probably be bagged and disposed of in
> infectious waste. It could quite possibly end up being the same as with CJD
> brain specimens. What do you all think about this?
> 
> 
> 
> Reference: Gerston, K.F. Blumberg, L. Tshabalala, V.A. Murray, J. Viability
> of Mycobacteria in Formalin Fixed Lungs. Human Pathology, Vol 35, No 5. May
> 2004. pp 571-575
> 
> 
> 
> Andrew Kennedy
> 
> Senior Science Officer
> 
> Anatomical Pathology
> 
> Concord Repatriation General Hospital
> 
> Hospital Road
> Concord NSW 2139
> 
> 
> 
> ph: +612 9767 6115
> 
> Fax +612 9767 8427
> 
> 
> 
> "corpora non agunt nisi fixata"
> 
> 
> 
> _______________________________________________
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> 
> 
> _______________________________________________
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> 
> 


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