TB growth from formalin
|From:||Vinnie Della Speranza |
Fred and others,
this seems like a good time to share what I have
learned regarding the growth of TB from formalin fixed tissue stemming from a
question I posted.
There is very little information reported in the
literature. It appears that most reports of TB growing from formalin are
anecdotal and not the result of scientific study. I'd like to thank Tim Morken
for assisting me with a PubMed search and forwarding along the citations he
A good reference for anyone so inclined
Kappel, TJ et al. The Viability of Mycobacterium tuberculosis in
Formalin-Fixed Pulmonary Autopsy Tissue: Review of the Literature and Brief
Report, Human Pathology Vol 27 No 12 (Dec 12, 1996)
The authors of this paper attempted to culture TB from
five formalin fixed cases with no success.
A later letter to the
International Journal of Tubercle Disease 2(6): 521-523, 1998 by Gerston, KF and
Gafoor, H. stated that these authors attempted to grow TB from 25 formalin fixed
cases. Of these, three cases, fixed for 4.5, 6.5 and 9 weeks respectively, did
grow TB in culture.
While this information is of some value, it
emphasizes that additional study is needed before we can really understand what
this information means to the way we practice. Is it possibe that an aqueous
aldehyde fixative has difficulty fully penetrating caseous, necrotic granulomas?
Clearly the TB organism has a talent for sequestering itself from the ravages of
the immune system and it may well be that it is sufficiently isolated as to
limit its exposure to a variety of external forces including tissue
Vinnie Della Speranza
Manager for Anatomic Pathology Services
University of South Carolina
165 Ashley Avenue Suite 309
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