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Microbiome Translocation

When components of the gut microbiome make it past our intestinal barriers and translocate to other body sites.


Combining amplicon sequencing and metabolomics in cirrhotic patients highlights distinctive microbiota features involved in bacterial translocation, systemic inflammation and hepatic encephalopathy (2018):

Phage passing the gut barrier when bacteria can't:

"Bacteria can directly release factors into the systemic circulation or can translocate into blood"

Bacteria in the mouth can cause dementia via translocation to the blood stream:

Phages can translocate through the mucosa to lymph and internal organs (2017):

Bacteria translocate into the blood in greater amount in ME, leading to inflammation (pg 10, Cornell)

Yale researchers describe research showing that harmful bacteria can make their way from the small intestines of mice to the lymph nodes, liver and spleen. Translocation of a gut pathobiont drives autoimmunity in mice and humans (2018): -

In patients with PDA (pancreatic ductal adenocarcinoma), pathogenic gut bacteria migrate to the pancreas through the pancreatic duct (2018):

"They found both healthy and disease-causing bacteria moved freely between the bladder and the female reproductive tract, even in healthy women" (2018): | and is similar to vaginal microbiome:

More of the Gut in the Lung: How Two Microbiomes Meet in ARDS (2018):

"once phages successfully enter the body, they reach most organs, including the central nervous system" (review, Mar 2019): Phage therapy: What factors shape phage pharmacokinetics and bioavailability? Systematic and critical review

Blood microbiome:

Review, May 2019: The Healthy Human Blood Microbiome: Fact or Fiction? "A number of studies on the HBM are mired by essential shortcomings, which casts some doubt over the validity of their results, but the notion that a healthy (non-diseased) human blood-microbiome exists cannot simply be discarded"

No evidence for a common blood microbiome based on a population study of 9,770 healthy humans (Mar 2023)

Even under healthy conditions, human blood contains bacterial DNA capable of triggering host innate immune responses (Hacker et al. 2002; Muruve et al. 2008; Nikkari et al. 2001).

Composition and richness of the serum microbiome differ by age and link to systemic inflammation (2018): - "In the present study, the analysis performed from whole serum cannot differentiate between microbial DNA fragments and intact microbes."

Comprehensive description of blood microbiome from healthy donors assessed by 16S targeted metagenomic sequencing (2016):

8/21/2017 Stanford study using shotgun sequencing says we still don't know 99% of human microbes: Humans are colonized by many uncharacterized and highly divergent microbes. "Through massive shotgun sequencing of circulating cell-free DNA from the blood, we identified hundreds of new bacteria and viruses which represent previously unidentified members of the human microbiome."

The dormant blood microbiome in chronic, inflammatory diseases (2015):

Circulating microbiome in blood of different circulatory compartments (2018):

Cultural Isolation and Characteristics of the Blood Microbiome of Healthy Individuals (2018):

Live commensal intestinal bacteria are present in the peripheral blood where they can induce inflammation. High rate of bacterial DNA in the blood samples indicates translocation in inflammatory bowel disease (2017):

Human Blood Harbors Cell-Free Microbial DNA (Jun 2021) Detection of cell-free microbial DNA using a contaminant-controlled analysis framework.

Brain microbiome:

Review, Oct 2023: Brain-inhabiting bacteria and neurodegenerative diseases: the “brain microbiome” theory "we provide a review of the evidence for and against the brain microbiome theory"

Much ado about nothing? Off-target amplification can lead to false-positive bacterial brain microbiome detection in healthy and Parkinson’s disease individuals (Mar 2021)

Brain microbiota disruption within inflammatory demyelinating lesions in multiple sclerosis (2016)

Do gut bacteria make a second home in our brains? (2018)

The human brain microbiome; there are bacteria in our brains! (2018)!/4649/presentation/32057

Is there a brain microbiome?

Mapping The Brain's Microbiome: Can Studying Germs In The Brain Lead To A Cure For Alzheimer's? (2017)

Bacteria Might Live In The Human Brain – And That Has Some Mind-Blowing Implications (2018)

Cerebrospinal fluid:

The virome of cerebrospinal fluid: viruses where we once thought there were none (Sept 2019) "By identifying a virome in the CSF of mostly healthy individuals, it is now less likely that any human body site is devoid of microbes"

Intervertebral discs (IVD)

Human intervertebral discs harbour a unique microbiome and dysbiosis determines health and disease (May 2020):