The validity of bacterial cultures from lung tissue for postmortem identification of pneumonia-associated pathogens has been questioned by pathologists. As a result, we investigated whether pathogenic bacteria that causes pneumonia could be detected using metagenomics analysis of lung tissue from 11 pneumonia patients and nine nonpneumonia cases collected at autopsy. We showed that metagenomics analysis of the postmortem lung microbiota could identify a bacterial genus as a pneumonia pathogen even when the genus was common and well-known. The presence of Enterobacteriaceae or anaerobic bacteria in the lung microbiota of non-pneumonia patients suggests postmortem transfer and replacement. Furthermore, based on postmortem anaerobic alterations and artificial culture conditions, we verified that postmortem bacterial culture from lung tissue might be deceptive for identifying the pneumonia pathogen. To our knowledge, this is the first study to show that metagenomics analysis of postmortem lung tissue may identify bacterial species that cause pneumonia under certain conditions.
