A protocol for quantizing total bacterial 16S rDNA in plasma as a marker of microbial translocation in vivo

Increased systemic microbial translocation contributes to the pathogenesis of various diseases.The magnitude of microbial translocation is measured by total bacterial 16S ribosomal DNA(rDNA)in plasma using quantitative PCR(qPCR).An evaluation of human systemic microbial translocation in vivo is crucial for revealing microbial product-mediated inflammation,innate immune activation and immune perturbation.The human gut harbors 1012 microorganisms per gram,and this is 10 times more than those from other sites.1,2 The intestinal mucosal barrier prevents pathogen invasion and nonpathogenic antigens residing within the intestinal lumen.1,2 Notably,the gut mucosal barrier prevents the host from being injured by pathogens,yet allows a very low level of bacterial product translocation to the system to maintain systemic immune homeostasis,as demonstrated by immune deficiencies in mice raised in sterile conditions.