Autopsy Identification of Viable Mycobacterium Tuberculosis in the Lungs of a Markedly Decomposed Body

Various infectious diseases, including COVID-19, MERS, and tuberculosis, are global public health issues. Tuberculosis, which is caused by Mycobacterium tuberculosis (MTB), is highly contagious and can be transmitted through inhalation of the bacteria. However, it has been assumed that the infectiousness of bacteria and viruses in dead bodies weakens as the time from death increases. In particular, there is little awareness of infection control measures concerning decomposed bodies or even the need for such measures. The deceased, in whom we discovered MTB 3 months following her death, was a woman in her 80s who died at home. We performed judicial autopsy, because police suspected homicide when her husband hanged himself. Obtained organs were used for microscopic examination by hematoxylin-eosin staining and Ziehl-Neelsen staining. In addition, real-time PCR and mycobacterial culture testing using Ogawa's medium were performed for the detection of MTB. We found that the MTB in the decomposed body remained viable and potentially infectious. To identify the bacterial strain further, we performed DNA-DNA hybridization and identified the strain as MTB complex. Potentially infectious live MTB survived in the dead body far longer than had been previously reported. Pathologists should consider microbial culture tests for all autopsied cases in which the decedent's medical history or macro-examination suggests possible infection, even when a long duration of time has passed since death. Pathologists and specialists who perform autopsies should recognize that all dead bodies are potentially infectious, including those in which long periods have elapsed since death.