[Histonet] RE: How long should autopsy/necropsy tissue be in fixation for a suspected TB case?

[Tony Henwood]

Christina,

The following might be useful:

Kappel et al (HUM PATHOL 27:1361--1364, 1996) attempted to grow TB from formalin fixed lung tissue that had previously been shown to be positive by sputum culture. They were unable to culture TB from these tissues.

Gerston et al (HUM PATHOL 35:571-575.2004) in South Africa analysed 138 formalin fixed lungs with histological evidence of AFB and were able to culture TB from 12 of these cases (one of these cases had been fixed for 80 days before being tested).

Gerston et al suggest that there is a risk of contracting tuberculosis from tissue that has been fixed in formalin, if aerosols or accidental inoculation should occur. 

Trimming and sectioning wax blocks are of concern but no studies have been done yet.

Of concern to histotechnolgists are:
1.	Tissue with Inflammation-induced Encapsulation may protect bugs from formalin.
2.	Formalin dilutes as it penetrates tissue.
3.	Formalin substitutes may not be germicidal.

Regards 
Tony Henwood JP, MSc, BAppSc, GradDipSysAnalys, CT(ASC), FFSc(RCPA) 
Laboratory Manager & Senior Scientist 
Tel: 612 9845 3306 
Fax: 612 9845 3318 
the children's hospital at westmead
Cnr Hawkesbury Road and Hainsworth Street, Westmead
Locked Bag 4001, Westmead NSW 2145, AUSTRALIA 


-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Thurby, Christina
Sent: Thursday, 14 April 2011 4:05 AM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] RE: How long should autopsy/necropsy tissue be in fixation for a suspected TB case?

Hi,
Do anyone have references for how long should autopsy/necropsy tissue be in fixation for a suspected TB case?  Is 72-96 hours fixation sufficient or should the time be extended to 5-7 days.
Thanks,
Christina Thurby
Bristol-Myers Squibb Company
Research Scientist I
812-307-2093 (tie 625)




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