RE: does TB grow out of formalin fixed tissue?

Vinnie, here is a review article on that subject:

Hum Pathol 1996 Dec;27(12):1361-4

The viability of Mycobacterium tuberculosis in formalin-fixed pulmonary autopsy tissue: review of the literature and brief report.

Kappel TJ, Reinartz JJ, Schmid JL, Holter JJ, Azar MM.

Department of Laboratory Medicine, University of Minnesota Hospital, Minneapolis, USA.

Formalin is commonly thought to decrease the risk of Mycobacterium tuberculosis infection. However, the true disinfection efficacy of formalin for tissue infected with M tuberculosis is unclear. We reviewed all pertinent literature from 1900 until the present regarding the disinfection efficacy of formalin for tissue infected with M tuberculosis. We also retrospectively cultured five cases of M tuberculosis from formalin-fixed archival pulmonary tissue. All cultures from our archived tissue were negative. The literature review revealed limited and contradictory information concerning the viability of M tuberculosis in formalin-fixed human tissue. There are no studies which specifically address the viability of M tuberculosis in tissue exclusively fixed in 10% buffered formalin. The disinfection efficacy of formalin for tuberculosis infected tissue remains unclear. Larger, prospective studies using current methodologies are needed to establish guidelines to ensure the safety for those handling infected, fixed tissue.

Publication Types:

Review
Review, Tutorial

PMID: 8958312 [PubMed - indexed for MEDLINE]

one of our pathologists indicated to me that she is certain that TB has been grown from formalin fixed tissue. She also believes this is true for HIV. This information was offered to contradict a statement I made to a resident that formalin fixation neutralizes blood borne pathogens.

I'd appreciate hearing from anyone who can speak to this issue ( efficacy of formalin to neutralize infectious organisms, especifically on the infectious potential of TB, HIV and Hep C) with some authority.

Of course there is always the possibility that tissues had not been adequately exposed to formalin which permitted some organisms to escape its effects and then grow in culture, as for example, when large organs are dropped in formalin without breadloafing.

appreciate your thoughts

Vinnie Della Speranza
Manager for Anatomic Pathology Services
Medical University of South Carolina
165 Ashley Avenue Suite 309
Charleston, SC 29425
Ph: 843-792-6353
fax: 843-792-8974