Tag Archives: Rob Knight Lab

Study shows Microbiome Differences Between Intensive Care Unit Patients Hospitalized From Healthy Patients

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The microbiome of patients admitted to the intensive care unit (ICU) at a hospital differs dramatically from that of healthy patients, according to a new study published in mSphere.

 

Researchers analyzing microbial taxa in ICU patients’ guts, mouth and skin reported finding dysbiosis, or a bacterial imbalance, that worsened during a patient’s stay in the hospital. Compared to healthy people, ICU patients had depleted populations of commensal, health-promoting microbes and higher counts of bacterial taxa with pathogenic strains – leaving patients vulnerable to hospital-acquired infections that may lead to sepsis, organ failure and potentially death.

What is dysbiosis?  Pathogens, antibiotic use, diet, inflammation, and other forces can cause dysbiosis, a disruption in these microbial ecosystems that can lead to or perpetuate disease  (1)

What makes a gut microbiome healthy or not remains poorly defined in the field. Nonetheless, researchers suspect that critical illness requiring a stay in the ICU is associated with the the loss of bacteria that help keep a person healthy. The new study, which prospectively monitored and tracked changes in bacterial makeup, delivers evidence for that hypothesis.
“The results were what we feared them to be,” says study leader Paul Wischmeyer, an anesthesiologist at the University of Colorado School of Medicine. “We saw a massive depletion of normal, health-promoting species.”
Wischmeyer, who will move to Duke University in the fall, runs a lab that focuses on nutrition-related interventions to improve outcomes for critically ill patients.

He notes that treatments used in the ICU – including courses of powerful antibiotics, medicines to sustain blood pressure, and lack of nutrition – can reduce the population of known healthy bacteria. An understanding of how those changes affect patient outcomes could guide the development of targeted interventions to restore bacterial balance, which in turn could reduce the risk of infection by dangerous pathogens.
Previous studies have tracked microbiome changes in individual or small numbers of critically ill patients, but Wischmeyer and his collaborators analyzed skin, stool, and oral samples from 115 ICU patients across four hospitals in the United States and Canada. They analyzed bacterial populations in the samples twice – once 48 hours after admission, and again after 10 days in the ICU (or when the patient was discharged). They also recorded what the patients ate, what treatments patients received, and what infections patients incurred.
The researchers compared their data to data collected from a healthy subset of people who participated in the American Gut project dataset. (American Gut is a crowd-sourced project aimed at characterizing the human microbiome by the Rob Knight Lab at the University of California San Diego.) They reported that samples from ICU patients showed lower levels of Firmicutes and Bacteroidetes bacteria, two of the largest groups of microbes in the gut, and higher abundances of Proteobacteria, which include many pathogens.
Wischmeyer was surprised by how quickly the microbiome changed in the patients. “We saw the rapid rise of organisms clearly associated with disease,” he says. “In some cases, those organisms became 95 percent of the entire gut flora – all made up of one pathogenic taxa – within days of admission to the ICU. That was really striking.” Notably, the researchers reported that some of the patient microbiomes, even at the time of admission, resembled the microbiomes of corpses. “That happened in more people than we would like to have seen,” he says.
Wischmeyer suggests the microbiome could be tracked like other vital signs and could potentially be used to identify patient problems and risks before they become symptomatic. In addition, now that researchers have begun to understand how the microbiome changes in the ICU, Wischmeyer says the next step is to use the data to identify therapies – perhaps including probiotics – to restore a healthy bacterial balance to patients.
Everyone who collaborated on the project – including dietitians, pharmacists, statisticians, critical care physicians, and computer scientists – participated on a largely voluntary basis without significant funding to explore the role of the microbiome in ICU medicine, says Wischmeyer.

 

To read this article in its entirety please click on the following link:

https://www.asm.org/index.php/journal-press-releases/94540-icu-patients-lose-helpful-gut-bacteria-within-days-of-hospital-admission?platform=hootsuite

Sources:

(1)  http://www.serestherapeutics.com

 

Scientific research demonstrates new evidence supporting Fecal Microbiota Transplant successful in treating C. difficile infections

Research published in the open access journal Microbiome offers new evidence for the success of fecal microbial transplantation (FMT) in treating severe Clostridium difficile infection (CDI), a growing problem worldwide that leads to thousands of fatalities every year.

Research led by Michael Sadowsky, Alex Khoruts, and colleagues at the University of Minnesota in collaboration with the Rob Knight Lab at the University of Colorado, Boulder, reveals that healthy changes to a patient’s microbiome are sustained for up to 21 weeks after transplant, and has implications for the regulation of the treatment. Findings also demonstrate the dynamic nature of fecal microbiota in FMT donors and recipients.

In FMT, fecal matter is collected from a donor, purified, mixed with a saline solution and placed in a patient, usually by colonoscopy. In contrast to standard antibiotic therapies                                (e.g., Vancomycin)  which further disrupt intestinal microflora and may contribute to the recurrence of CDI, FMT restores the intestinal microbiome and healthy gut function.

Using DNA samples of healthy individuals from the Human Microbiome Project (HMP) as a baseline, Sadowsky and his team compared changes in fecal microbial communities of recipients over time to the changes observed within samples from the donor. Significantly, the composition of gut microbes in the both donor and recipient groups varied over the course of the study, but remained within the normal range when compared to hundreds of samples collected by the HMP.

According to Sadowsky, the findings have important implications for a range of diseases associated with microbial imbalance, or dysbiosis, and could influence the regulatory regime surrounding FMT, currently treated as a drug by the U.S. Food and Drug Administration (USFDA).

“The dynamic nature of fecal microbiota in both the donor and recipients suggests that the current framework of regulation, requiring consistent composition, may need to be reexamined for fecal transplantations,” says Michael Sadowsky. “Change in fecal microbial composition is consistent with normal responsiveness to shifts in the diet and other environment factors. Variability should be taken into account when comparing microbial composition in normal individuals to those with dysbiosis characteristic of disease states, especially when assessing clinical interventions and outcomes.

Also discovered in the research, the performance of frozen and fresh preparations of fecal material was indistinguishable. Though the sample was limited and warrants further study with a larger cohort, it has several implications for the widespread adoption of FMT. The frozen preparation greatly simplifies the standardization and distribution of the fecal material. It also facilitates long-term storage of donor material for future study and makes FMT accessible to a greater number of physicians and patients. Finally, it offers advantages over fresh material in the testing of fecal samples for pathogens, which in some cases can take several weeks to complete.

While FMT is particularly successful in patients who suffer from recurrent CDI, University of Minnesota researchers led by Sadowsky and Dr. Alex Khoruts are currently preparing for a clinical trial using FMT to improve insulin sensitivity in pre-diabetic patients and to treat metabolic syndrome.

 

To read the article in its entirety please click on the following link:

http://www.eurekalert.org/pub_releases/2015-04/uom-nes040915.php