Time-dependent post mortem changes in the composition of intestinal bacteria using real-time quantitative PCR

Area of Science:

• Microbiology
• Forensic Science
• Gastroenterology

Background:

• Understanding post-mortem changes in gut microbiota is crucial for forensic and medical investigations.
• Previous research has not extensively documented temporal shifts in major bacterial populations after death.

Purpose of the Study:

• To investigate the stability of major gut bacterial populations in post-mortem samples.
• To determine the effect of post-mortem interval on bacterial ratios in rectal and cecal tissues.

Main Methods:

• Quantitative real-time PCR was used to analyze bacterial ratios.
• Fecal samples from healthy volunteers and rectal/cecal samples from 61 autopsies were examined.
• Bacterial populations studied included Bacteroides sp., Bifidobacterium sp., Clostridium leptum, Clostridium coccoides, Streptococcus sp., Lactobacillus sp., and Enterobacteriaceae.

Main Results:

• Bacterial ratios in stool and rectal autopsy samples showed no significant changes up to 5 days post-mortem.
• Significant post-mortem time-dependent differences were observed in the cecum for Bacteroides sp. (p=0.014) and Lactobacillus sp. (p=0.024).

Conclusions:

• Rectal autopsy samples are reliable for investigating major gut bacterial populations up to 5 days post-mortem.
• The cecum exhibits more dynamic changes in bacterial composition over the post-mortem interval compared to the rectum.