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 infl ammation, 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. The intestinal mucosal barrier prevents pathogen invasion and nonpathogenic antigens residing within the intestinal lumen. 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. Therefore, the quantification of total bacterial 16S rDNA in plasma is used to assess human and animal systemic microbial translocation in vivo, and thus is a great tool to study the role of systemic microbial products in disease pathogenesis and mucosal barrier function. The bacterial 16S rDNA assay can analyze 90% of bacterial strains, including Gram-positive and Gram-negative bacteria. However, use of this assay is highly challenging because of its high technical demands and the risk of contamination. Nonetheless, we have performed this assay successfully and have published several studies regarding the assay’s use. A detailed protocol and results from different cohorts for quantifying total bacterial 16S rDNA in plasma is reported here.


Dr. Jiang has completed her MD from the Capital Medical University, Beijing, China and postdoctoral studies from Case Western Reserve University, School of Medicine, Cleveland, Ohio, USA. Currently, she is the associate professor in the Department of Microbiology and Immunology, Medical University of South Carolina, USA. She has published more than 58 papers in reputed journals as the indepedent investigator since 2012 and has been serving as a reviewer for US National Institute of Health grant review, as well as an editorial board member of Journal of Neuroimmune Pharmacology.