The effect of the embalming fluid, used by the Department of Basic Medical Sciences (UFS), on the viability of Mycobacterium TB in human cadaver lung tissue
Correia, Janine Carla
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Embalming fluid contains substances such as formalin, ethanol, phenol, and other solvents to prevent decomposition temporarily. These agents disinfect, preserve, and/or sanitize. The risk of contracting a disease such as tuberculosis (TB) among persons, who are in close contact with recently deceased people, is high and the risk varies according to occupation. Workers at Anatomy Departments and embalmers are some of those people who are at a greater risk of contracting tuberculosis carried by cadavers. The question thus arises whether the penetration of formalin and other embalming agents into the tissue infected with Mycobacterium tuberculosis (MTB) is sufficient to render the bacilli non-infectious. The aim is to test the efficacy of the embalming fluid used at the department of Basic Medical Sciences (UFS) on eliminating Mycobacterium tuberculosis in human cadaver lung tissue. The cadavers were accompanied by their death certificates indicating the cause of death. Only cadavers whose death certificate indicated that the cause of death was TB, was selected to be included in the study. Closed needle biopsies were performed on 20 cadavers to obtain lung tissue from the apical and hilar areas. With the use of a pro-cut biopsy needle, a sample of lung tissue was obtained by inserting the needle through the 3rd intercostal (hilar sample) and the supraclavicular space (apical sample). The first sample was taken before embalming. The second sample 3 weeks after embalming. Tissue was then retrieved and deposited into a sterile specimen container, with saline as transport medium, and transported to Pathcare Laboratory (Drs Dietrich, Voigt, Mia, and partners) in Bloemfontein. The following diagnostic tools were used by Pathcare: direct microscopy from aspirates (lungs in the case of Pulmonary TB or from granulomatous lesions), MGIT culture, identification using PCR techniques, if positive. Before embalming 50% of the apical samples tested positive for MTB and 3 weeks after embalming none tested positive for MTB. Before embalming 40% of the samples taken from the area close to the hilus (perihilar), tested positive for MTB, 3 weeks after embalming none tested positive. The results show that 3 weeks after embalming none of the tested lung samples contained viable MTB. Thirteen of the 20 cadavers tested did have a viable strain of MTB before embalming occurred. It is of special interest to mention that one cadaver still had viable MTB 36 days after death. According to previous studies, after death, MTB can remain infectious for about 8 days in unembalmed lung tissue and up to 14 days if stored between 2 - 4oC. From this result, it is clear that MTB can survive in dead bodies with significant post-mortem intervals. It is evident from the results that the embalming fluid used at the department of Basic Medical Sciences (UFS) renders the bacilli non-infectious, because no growth was indicated 3 weeks after embalming.