Dear Bob,
while I have no experience in this, having always accepted that well fixed
tissue kills everything bacterial and viral, it is clear that whole organs
or very thick tissue even at three days is still unfixed in the middle, and
such tissues will require a minimum prosection to include slicing into
thickness's thin enough to allow good penetration in 24 hrs or less. Many
texts quote 5-10mm, and put absorbent material between slices. While this is
somewhat off-putting, you might consider adding up to 5% Sodium Lauryl
Sulphate to your NBF as an agent to facilitate penetration of fixative, this
agent is used esp. to obtain quicker and deeper penetration of disinfectants
and fixatives (Formalin) on Ovine and Bovine Hoof for treatment of footrot;
and I see no reason why it would not work just as efficiently for Histology
as the original Ag. Dept. lab at Bairnsdale Vic.Aust. assessed it's
effeciency by doing histology on the hoof samples used in the trial back in
the early eighties- their results were published at the time.
A second suggestion might be to use a fixative like carnoys, where there
would be a defatting effect on any Mycobacteria allowing access to the
fixative at an earlier stage and possibly earlier cell death- thereby
earlier processing.
Hoping these suggestions are of some use.
Yours in Histology, Mike Rentsch (Downunder)
-----Original Message-----
From: Bob Bacon <BBacon@Prodigy.net>
To: Histonet@pathology.swmed.edu <Histonet@pathology.swmed.edu>
Date: Thursday, 19 November 1998 1:41
Subject: viability of tuberculosis bacteria


>Hi all:
>We receive primate specimens in our research lab at the University of
>Missouri Veterinary Patho-Biology Lab that is often sent to us and is
>often infected with Tuberculosis. My question is how effective is
>formalin in killing tuberculosis bacteria and how long should we fix the
>tissue to ensure that the organism is non-infectious.  We've been
>flagging the specimens for 3 days to insure that they are well fixed
>before processing and cutting?  Is this necessary?  Our client would
>like faster turn around time?  Whats the consensus out there?
>Bob Bacon  HT ASCP
>Dept of Veterinary Pathology
>University of Missouri
>