Postmortem microbiological sampling: a prospective ESGFOR-supported study on relevance, timing, and site selection

Postmortem microbiological tests can help confirm infectious causes of death and identify the responsible microorganism (MO). However, challenges arise due to the lack of consensus and regulatory guidelines. This prospective single-center study conducted at University Hospitals Leuven from 2013 to 2016, aimed to assess the relevance as well as site- and time-related aspects of postmortem microbiology. A total of 200 clinical and forensic autopsies were included in the study, with 1321 samples collected. Approximately one-fifth of cases revealed an infectious cause of death, predominantly pneumonia. Histopathological classification into infectious and non-infectious causes of death served as the gold standard against which microbiological results were compared. The group of MO (i.e., group 1 and group 2 pathogens as well as a small number of specific pathogens), the number of positive sites, specific sampling sites, and the unique presence of a pathogen at a given site were all significantly related to infectious deaths. We propose that the concept of polymicrobial overgrowth as contamination primarily pertains to non-pathogenic MOs. We recommend the sampling of internal or external peripheral blood, heart blood, left lung, and spleen as part of a standardized protocol. Although the postmortem interval (PMI) was shown to affect microbiological results, its clinical relevance warrants further investigation.