High-throughput sequencing to evaluate the effects of methamphetamine on the succession of the bacterial community to estimate the postmortem interval.

In forensic medical examinations, estimating the postmortem interval (PMI) is an important factor. Methamphetamine (MA) is a synthetic stimulant that is commonly abused, and estimation of the PMI after MA abuse has become one of the main tasks in forensic investigation. Microorganisms play a vital role in carrion decomposition. Analysing the bacterial succession patterns can be used as a forensic tool to estimate the PMI. The present study aimed to analyse bacterial succession changes during the decomposition of MA to estimate the PMI. We analysed bacterial communities in rabbits treated with three different concentrations of MA (0, 22.5, and 90 mg/kg) under the natural conditions of 20 °C and 70% humidity by sequencing 16S rRNA gene amplicons using the Illumina MiSeq system. We obtained 2 374 209 high-quality sequences and 2 937 operational taxonomic units (OTUs). The relative abundances of the bacterial communities varied markedly in response to different MA concentrations. Interestingly, in response to the different concentrations of MA, Bacteroidetes became disparate in the rectum in the late PMI. Increased numbers of bacterial taxa were identified in the rectum and buccal cavity samples, except at the highest concentration of MA in the rectum samples when PMI was 0-h, than were present in live rabbits. Meanwhile, the PMI correlated significantly with bacterial succession at different taxonomic levels. Our results suggested that bacterial community succession could be used as a "microbial clock" to estimate the PMI in cases of MA-related death; however, further study is required to gain a deeper understanding of this concept.