Identification of Antemortem and Postmortem Injuries in Nude Mice Based on Microbial Communities.

Abstract

Objectives: To establish antemortem and postmortem injury models in nude mice, observe the morphological changes of the wounds and the changes of the microbial communities in the wounds at different time points after the injury, and analyze the differences between antemortem and postmortem wounds.

Methods: Abdominal injury models were established in 48 BALB/c nude mice, which were classified into antemortem injury, 4 h and 72 h postmortem injury groups, and the gross manifestations and histopathological changes were observed on days 1, 3, 5, 8, 11 and 15 after injury. The microbial communities in the wounds were analyzed by 16S rRNA sequencing technology. QIIME 2 software was used to calculate Shannon and Observed species indices. The Kruskal-Wallis test was used to determine statistical differences in α-diversity between groups. Jaccard similarity coefficients were calculated by using R v4.3.0 software and applied to the principal co-ordinates analysis to demonstrate inter-sample differences. Permutational multivariate analysis of variance (PERMANOVA) was used to analyze the differences between groups in the composition of bacterial colonies, and R² values were calculated.

Results: On days 8, 11 and 15 after injury, the antemortem and postmortem injuries could not be differentiated by morphological examination; the Shannon index and Observed species index were statistically different between the antemortem injury group and the 72 h postmortem injury group; the Jaccard similarity coefficient of the microbial community was statistically different between the antemortem injury group and the 72 h postmortem injury group. The PERMANOVA R² value gradually increased with the extension of time (0.22-0.61).

Conclusions: Through the analysis of the wound microbial community, the microbial composition of wounds at different time points can be identified and compared, which provides a new perspective and method for the differentiation of antemortem injuries from postmortem injuries, with good application prospects.