Tag Archives: C difficile research and development

Dr Klaus Aktories and Dr Panagiotis Papatheodorou from the University of Freiburg have identified the molecular docking site of a bacterial toxin

The pharmacologists and toxicologists Prof./ Dr. Klaus Aktories
and Dr. Panagiotis Papatheodorou from the University of Freiburg have identified the molecular docking site that is responsible for the C. difficile toxin’s being able to bind to its receptor on the membrane of the intestinal epithelium.

 

Caption:  Bacterial toxins usually exert their full deadly effect in the host cell’s interior. The toxins overcome the cell membrane by binding to a surface receptor, which conveys them into the cell’s interior.

Credit© Panagiotis Papatheodorou

Clostridium difficile is a dangerous intestinal bacterium that can cause severe diarrhoea and life-threatening intestinal infections after long-term treatment with antibiotics. The pharmacologists and toxicologists Prof. Dr. Dr. Klaus Aktories and Dr. Panagiotis Papatheodorou from the University of Freiburg have identified the molecular docking site that is responsible for the C. difficile toxin’s being able to bind to its receptor on the membrane of the intestinal epithelium. This docking site functions like an elevator, transporting the toxins into the cell’s interior. By binding to the surface receptor, the toxins are able to overcome the cell membrane. Once inside the cell, C. difficile exerts its full lethal effect. “Bacteria are becoming increasingly resistant to antibiotics. That’s why new types of therapy that aren’t based primarily on bacteria are necessary,” Aktories said. “Our goal in the future should be to reduce the toxicological potential of toxins as well,” he added. The team of researchers has recently published their results in the Journal of Biological Chemistry.

The intestinal pathogen C. difficile is most commonly found in hospitals and is often acquired by older people and people with weakened immune systems. In Western countries, infections with so-called hypervirulent strains of C. difficile are rapidly increasing and are much more dangerous and more difficult to treat. The pathology of C. difficile infections is primarily triggered by two toxins released by the pathogen, which then damage the intestinal epithelium. Particularly dangerous hypervirulent strains produce a third toxin, C. difficile transferase (CDT). This CDT toxin modifies the cytoskeleton, causing the host cells to collapse and die. Aktories and Papatheodorou identified the surface protein LSR (lipolysis-stimulated lipoprotein receptor) as the receptor for the CDT toxin already in 2011. It is through the LSR that CDT enters the host cell.

Papatheodorou, Aktories and their team of researchers have now identified the regions in the CDT toxin and the LSR receptor that interact with one another. In order to achieve this, the scientists genetically designed truncations of the toxin and the LSR receptor as well as cells without LSR. They then tested whether or not the CDT toxin could bind to its receptor and be absorbed in the cell. They discovered that the parts of the toxin that interact with the receptor are much smaller than previously believed. All that is necessary for toxin absorption is the part of the receptor outside of the cell. “In the future, it should be possible to block these areas in the toxin and receptor in order to prevent the toxin from entering the host cell,” Papatheodorou explained.

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Papatheodorou and Aktories are researchers at the Institute of Experimental and Clinical Pharmacology and Toxicology at the University of Freiburg. Aktories is also a member of the cluster of excellence BIOSS Centre for Biological Signalling Studies at the University of Freiburg.

To read the article in its entirety click on the link below:

http://www.eurekalert.org/pub_releases/2015-06/b-cf-mds060915.php

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

C. diff. and Healthcare-Associated Infections Discussed Live on C. diff. Radio

#CdiffRadio

C Diff Foundation, Sponsor, with Founder            Nancy C. Caralla, Executive Director and               Dr. Chandrabali Ghose, Chairperson of the Research and Development Community will be broadcasting live on Tuesdays delivering the most up-to-date information pertaining to a leading super-bug/ Healthcare Associated Infection (HAI),  C. difficile, with additional HAI’s, and a variety of related healthcare topics.

Topic experts will be joining your hosts to discuss prevention, treatments, clinical trials, and environmental safety products on a global level.

Tune in Tuesdays beginning March 3rd at 11 AM Pacific Time (2 PM Eastern Time, 7 PM UK) on the VoiceAmerica network  http://www.voiceamerica.com/show/2441/c-diff-spores-and-more

 

C. difficile (C.diff.) News – University of Michigan Scientists discover how C. diff. wreaks havoc in the gastrointestinal system

Study in mice could lead to better treatment and prevention for humans

Sometimes, science means staying awake for two days straight.

But losing sleep is a small sacrifice to make, if you want to learn more about tiny bacteria that sicken half a million Americans each year, kill more than 14,000 of them, and rack up $4.8 billion in health care costs.

That’s what drove a team of University of Michigan scientists to work around the clock to study the bacterium called Clostridium difficile, C. difficile (C.diff.), the bane of hospitals and nursing homes. Many patients can develop it after taking antibiotics to treat infections.

In a new paper in the journal Infection and Immunity, the researchers lay out for the first time exactly how C. difficile wreaks havoc on the guts of animals in a short time, and causes severe diarrhea and life-threatening disease in humans.

Despite the heavy toll the organism takes, no team had ever been able to measure C. difficile activity over time in this way. Their findings could help lead to better prevention and treatment of C. difficile infections.

A fast track to disease

The researchers started by introducing C. difficile spores into mice via their mouths – similar to what might happen in a hospital environment where spores from past patients’ infections abound. Then, they studied what happened after the spores entered the body, by taking gut samples at regular intervals and studying them under special conditions. The animals had all received antibiotics.

Through their hours-long surveillance, the researchers found that it took C. difficile only about 24 hours to go from hard spores to toxin-producing, diarrhea-inducing cells all the way at the other end of the digestive tract, in the large intestine.

The researchers also show that bile acids in the gut “woke up” the dormant bacteria spores, and that they grow into cells in the small intestine within 24 hours of exposure.

Because antibiotic have the ability to disrupt the gut’s normal community of other bacteria – called the gut microbiome — C. difficile cells could continue down to the large intestine and start their toxic effects on the cells that line the colon.

When they tested the contents of the small intestine separately, they also showed this happens whether or not the animals have received antibiotics.

In the large intestine, they even saw how C. difficile cells formed spores  – allowing them to survive the exit from the body in feces and go on to infect a new host.

“If we can understand the process that specific bacteria use to germinate and get established, we may be able to intervene more effectively,” says Vincent Young, M.D., Ph.D., the senior author of the new study, a professor at the U-M Medical School and co-leader of the school’s Host Microbiome Initiative. “We assume that antibiotics change the gut microbiome, but we haven’t known how that allows C. difficile to gain a foothold and begin to ramp up growth.”

First author Mark Koenigsknecht, Ph.D., a postdoctoral fellow in Young’s lab who is now continuing his research at the U-M College of Pharmacy, was one of the researchers who was up all night to get data for the experiment.

“We introduced 100 spores through the mouth, and within six hours we could find 1,000 cells in the intestinal tract,” he notes. “We chose this strain of C. difficile because of its rapid ability to cause disease in animals, but we didn’t think it would happen that quickly.”

Tracking C. difficile’s effect on the gut

 

Click the image to see it larger

The U-M team used a mouse model they developed, and a common antibiotic in the cephalosporin class. The strain of C. difficile used in the experiment originated with a patient years ago, but is available for purchase as a laboratory culture.

Special oxygen-free chambers were
used in the research,
 giving researchers
the ability to study the gut microbiome

in the anaerobic environment that’s present
inside the body.

Working in facilities made possible by the Host Microbiome Initiative, they took samples at regular intervals from seven different areas of the digestive tracts of the mice. They then whisked the samples into special oxygen-free facilities, called anaerobic chambers, that allowed them to see the amount and forms of C. difficile present in each gut region.

With the help of Patrick Schloss, Ph.D., a professor in the Department of Microbiology & Immunology, the researchers used DNA analysis to see what the entire gut microbiome looked like in antibiotic-treated animals and those that hadn’t been treated. The antibiotics really disrupted the community of bacteria in the small intestine, and C. difficile came to dominate in 36 hours.

They also examined the intestinal tract under a microscope. The toxin produced by C. difficile cells in their vegetative, or growing, state causes an effect on the cells that line the digestive tract, causing them to become “leaky”, raising the alarm among nearby immune system cells, and leading to diarrhea. The cell changes were seen in the large intestine about 30 hours after spore introduction.

Next steps

Three graphs showing how quickly
C. difficile took over the guts of
antibiotic-treated mice.

Koenigsknecht notes that this is the first time researchers have seen in a living animal that toxin production, and production of new spores of C. difficile capable of surviving outside the body, occur at the same time. This indication that the two processes are linked, and that they are switched on by some factor in the body, is intriguing, he says.

Now, the effort to figure out what that signal is, whether different strains of C. difficile act differently, and who is most vulnerable to its effects, will continue.

Koenigsknecht has teamed with College of Pharmacy professors to test the use of a seven-foot-long tube that can be threaded down the human digestive tract and used to retrieve samples at different locations along the way. Originally developed for testing how drugs are broken down and used by the body, it could provide an entirely new window into the human microbiome.

“Now that we understand what C. difficile is doing, we can also go and ask more questions about how the machinery inside the cell is turning on,” he says. “We have to know how to study it before we can cure it.” Animal-based research is vital to this effort.

Young notes that there are many ways C. difficile could take over an antibiotic-decimated gut. “Does it prevent other bacteria from growing, or out-compete them by eating faster? Does it communicate with the cells of the gut lining? We’re trying to figure out the interaction between the ‘good bugs’ and the ‘bad bugs’, and the lining of the gut.” Young is an associate professor of infectious diseases and of microbiology and immunology.

In addition to Young, Schloss and Koenigsknecht, the study’s authors are Casey Theriot, Ingrid Bergin and Cassie Schumacher.

The research was funded by the National Institutes of Health grants U19AI090871, K01GM109236 and 5R01GM099514. It used the U-M Metabolomics Core, funded by NIH grant U24 DK097153. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health

For entire article please click on the link below:

http://www.uofmhealth.org/news/archive/201502/stalking-wily-foe-u-m-scientists-figure-out-how-c-difficile

Rebiotix, Inc. PUNCH CD 2 Study – Second Clinical Trial Initiated

Update

24 November 2014

Rebiotix has initiated our second clinical trial (PUNCH CD 2) focusing on the treatment of recurrent C. difficile infection!

REBIOTIX, INC.

The PUNCH CD 2 study is a Phase 2B randomized controlled trial to assess the effectiveness and safety of RBX2660 (microbiota suspension) for the treatment of recurrent               Clostridium difficile (C. diff.)  infection.

About the Study   The PUNCH CD 2 study is the first multicenter prospective, multicenter, randomized, placebo-controlled, double-blind study of a microbiota restoration therapy. It has been designed to provide the highest quality of evidence to-date about this non-antibiotic approach to treating recurrent C. diff. infection.

Approximately 117 patients at over 20 sites in the US and Canada are expected to be enrolled in study.

Patients will be randomized into three different study groups: one group will receive two enemas containing RBX2660; another group will receive two enemas without the active drug; and the third group will receive one enema with RBX2660 and one without.  If a patient’s C. diff. infection reoccurs before 8 weeks after treatment, he or she may be eligible to crossover to receive active treatment with RBX2660.

All patients will be followed for 24 months after treatment.

Further Study Details

For more information on the study you may:

Find Out if You Could be Eligible

A physician participating in the PUNCH CD 2 study will determine if you are eligible to participate in the study. However, you can take a brief survey (less than 1 ½ minutes to complete) to learn if you meet the major study eligibility criteria.

How to Enroll as a Participant

If a study physician thinks you may be a good candidate, you will be given complete information about the study including the responsibilities for participation. You can find out if there is a study site near you by reviewing the clinical study site locations for PUNCH CD 2.


Caution: New Drug – Limited by Federal (or United States) law to investigational use.

 

*Please note – The C Diff Foundation does not endorse this product or any product and this posting is strictly for informational purposes only.