Tag Archives: C diff research and developnent

Researchers Make Chemical Changes In the InsP6 Inhibitor To Improve Its Hydrogen Bonding Capabilities With C. difficile Toxins

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Infections with bacterium Clostridium difficile have rapidly become a significant medical problem in hospitals and long-term care facilities. The bacteria cause diarrhea and life-threatening inflammation of the colon by producing toxins that kill the endothelial cells that form the lining of the gut.

Although a natural inhibitor of these toxins, called InsP6, works in the test tube, it is not very efficient when administered orally.

Traditional methods to optimize InsP6 have until now not been successful, but researchers at Baylor College of Medicine have discovered that changing one atom in InsP6 can increase its ability to neutralize the toxins by 26-fold.

The results appear in Science Advances.

“The toxins, called TcdA and TcdB, are very large molecules that kill the cells very efficiently,” said Dr. Tor Savidge, associate professor of pathology and immunology and of pediatrics, director of the Savidge Lab at the Texas Children’s Microbiome Center and senior author of the paper. “It’s like delivering a warhead into the cell. The toxins bind to the cell and the cell internalizes them in a sack of cell membrane called endosome. Not all of the toxin will exit this sack to kill the cell, just the little warhead pokes its head out. Another section of the toxin senses when the warhead is outside the sack and cleaves it. The warhead is released, interferes with basic functions and kills the cell,” said Savidge.

To neutralize the toxins, the researchers targeted the section that senses when the warhead is inside the cell, called allosteric modulator. “The strategy we have tried is to make the toxin ‘think,’ before it binds to and enters the cell, that the warhead is ready to be released, so it releases it prematurely,” said Savidge. When the warhead is released outside the cell, it is neutralized. InsP6, the toxins’ natural inhibitor, works this way, but is not very efficient.

Finding molecules that would bind to the allosteric modulator and trigger the premature release of the warhead involved analyzing and testing half a million molecules listed in large databases. Dr. Numan Oezguen, a member of the Savidge Lab, used virtual drug screening to sift through the databases to identify candidate molecules that most likely would bind to the allosteric modulator. One of his screening strategies consists of creating virtual 3-D structures of the molecules, projecting them on a large screen and using 3-D glasses to determine the most likely interactions between molecules. The molecules whose virtual analysis suggested they would bind to the allosteric modulator were then tested in the lab.

“We found that allosteric mechanisms are very complicated,” said Savidge. “You can find something that binds and you think, well, this is probably a good candidate for this, but it’s not right. It binds, but it doesn’t trigger the premature release of the warhead.”

Far from discouraging their efforts, the results motivated the researchers to better understand what makes interactions between molecules stronger or weaker. Their comprehensive analysis of numerous molecules provided insights into how water contributes to molecular interactions, in particular those involving hydrogen bonds, one of the most important bonds between molecules. The roles of water and hydrogen bonding had not been considered in this way before.

“When you take water into consideration you need to acknowledge that it can form hydrogen bonds, which may or may not compete or interfere with those formed between other molecules such as C. difficile toxins and their inhibitors, which interact in the gut, surrounded by water,” said Savidge.

“Before we considered the role of water, the predominant idea was that to strengthen the interaction between molecules the ability to form hydrogen bonds had to be made as strong as possible in the drug. It turns out this is not the case,” said Oezguen. Many times drugs designed to be able to make strong hydrogen bonds bind poorly to their targets.

The researchers discovered that to enhance the binding of a drug to its target, both sides of the hydrogen bond, the side on the drug and the one on the target, have to have either significantly stronger or significantly weaker hydrogen bonding capabilities.

On the other hand, a mixed strong-weak hydrogen bond pairing decreases the overall binding of the drug to its target, in some cases by 3 million fold. The decrease in binding is the result, the researchers propose, of water molecules forming hydrogen bonds with the drug and its target, therefore preventing the drug and the target from forming hydrogen bonds between them.

With all this information in hand, the researchers proceeded to make chemical changes in the InsP6 inhibitor to improve its hydrogen bonding capabilities with
C. difficile toxins.

One of the modifications, changing one single atom in InsP6, strengthened InsP6 binding to the allosteric modulator by 26-fold. This observation builds on a report published by Savidge in Science last year exploring the role of water interactions in the origin of enzymatic catalytic power.

Plans are currently underway to exploit these fundamentally new concepts in the precision design of future therapeutic applications.

Other contributors to this work are Deliang Chen, now in Gannan Normal University, China, who contributed conceptual and theoretical proof of the hydrogen bonding pairing principle; Petri Urvil from Baylor performed lab studies; Colin Ferguson from Echelon Biosciences, Inc. synthesized the more efficient inhibitor; and Sara Dann from the University of Texas Medical Branch in Galveston, contributed animal studies.

This work was supported by grants RO1AI100914 and DK56338 from the National Institute of Allergy and Infectious Diseases and the National Institute of Diabetes and Digestive and Kidney Diseases at the NIH, and the National Science Foundation of China (21473041).

Source: https://www.bcm.edu/

 

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

http://www.azom.com/news.aspx?newsID=45377

C. diff. Spores and More Global Broadcasting Network Welcomes Guests; Dr. Michael Stecher, Dr. Sushma Shivaswamy, and Mr. Kelly Thornburg of XBiotech

XBiotech will discuss their novel True Human ™ approach on Tuesday, February 2nd at
10 a.m. Pacific Time,,   11 a.m. Mountain Time,
12 p.m. Central Time,    1 p.m. Eastern Time.

on C. diff. Spores and More™”  Global Broadcasting Network – an educational program dedicated to  C. difficile Infections  and more —  brought to you by VoiceAmerica and sponsored by Clorox Healthcare

http://www.voiceamerica.com/show/2441/c-diff-spores-and-more

 

This episode introduces XBiotech, developer of True Human ™ therapeutic antibodies.  XBiotech has an exciting pipeline of product candidates in various areas of medicine.  The Company recently anounced the launch of a research and development program to develop a first-in-class oral monoclonal antibody against Clostridium difficile (C. diff. ) infection.  The Company will discuss the need for an effective C. difficile therapy, their novel approach to treating the infection as well as efficiency in their manufacturing technology.

Join guests Dr. Michael Stecher,MD,  Medical Director, Dr. Sushma Shivaswamy, Ph.D., Vice President of Research and Development and Mr. Kelly Thornburg, Senior Vice President of Operations as they discuss how XBiotech is pioneering a new era in the discovery and development of targeted antibodies therapeutics.

 

XBiotech

 

XBiotiech is rethinking the way medicines are discovered and commercialized– from pioneering ways to create safer drugs that harness our natural immunity to disease, to developing technology that enables rapid transition from discovery to large-scale manufacturing.  “At XBiotech we believe there is vast potential for next generation antibody therapies derived from natural immunity to disease.  We believe our innovation in technology and in the clinic enables us to bring our new discoveries to patients more efficiently than any other bio-pharmaceutical developer in the industry. ”

 

Michael G. DeGroote School of Medicine at McMaster Researchers Discover New Superbug Test With Quick Diagnosis

Microscope - 5

McMaster researchers have come up a way for inventing molecule probes to quickly identify deadly bacterial strains of infectious disease.

The find, published as a “hot paper” by a German scientific journal because of its importance, shows promise for detecting specific strains of bacteria and tracking their specific trail of illness.

 

“With this new technology we will be able to develop molecular tools to recognize any superbug down to the specific strain, and there will be many wide-ranging applications,” said Yingfu Li, principal investigator and a professor of biochemistry and biomedical sciences for the Michael G. DeGroote School of Medicine at McMaster.

The scientists have found a way to make DNAzymes, or single-stranded catalytic DNA molecules from a simple test tube technique that allows for isolation of rare DNA sequences with special functions.

The research team’s first success was the development of a that precisely recognizes the strain which caused the 2011 Hamilton, Ont. outbreak of Clostridium difficile infection. This strain was very infectious, resistant to antibiotics and even fatal to some patients. Instead of having to do several different tests to narrow down to a positive identification of the specific strain, the researchers can now quickly pinpoint this superbug using their new molecular probe.

“This sets up the stage for numerous other applications where we can exploit synthetic DNAzyme probes for diagnosing infectious disease,” said Li.

The test can be done in less than an hour, compared to the current 48 hours, allowing for rapid, more accurate treatment of patients.

“This technology can be extended to the further discovery of other superbug strain-specific pathogens.  For example, such technology would prove useful in the identification of hypervirulent or resistant strains, implementation of the most appropriate strain-specific treatments and tracking of outbreaks”, said Bruno Salena, a co-author of the study, an associate professor of medicine for the Michael G. DeGroote School of Medicine and a gastroenterologist with Hamilton Health Sciences.

“This technology is inexpensive, accessible without a lab, and will ultimately be adaptable to identify not just many other bacteria or viruses, but even other diseases,” he said.

Resource:

To read the article in its full version click on the link below:

 

http://m.phys.org/news/2015-12-infectious-disease-quick-diagnosis.html

 

 

Asymptomatic carriers of toxigenic C. difficile in long-term care

Asymptomatic carriers of toxigenic C. difficile in long-term care facilities: a meta-analysis of prevalence and risk factors.

Abstract

BACKGROUND:

The impact of Clostridium difficile colonization in C. difficile infection (CDI) is inadequately explored. As a result, asymptomatic carriage is not considered in the development of infection control policies and the burden of carrier state in long-term care facilities (LTCFs) is unknown.

PURPOSE:

To explore the epidemiology of C. difficile colonization in LTCFs, identify predisposing factors and describe its impact on healthcare management.

DATA SOURCES:

PubMed, Embase and Web of Science (up to June 2014) without language restriction, complemented by reference lists of eligible studies.

STUDY SELECTION:

All studies providing extractable data on the prevalence of toxigenic C. difficile colonization among asymptomatic residents in LTCFs.

DATA EXTRACTION:

Two authors extracted data independently.

STATISTICAL METHODS:

The pooled colonization estimates were calculated using the double arcsine methodology and reported along with their 95% random-effects confidence intervals (CIs), using DerSimonian-Laird weights. We assessed the impact of patient-level covariates on the risk of colonization and effects were reported as odds ratios (OR, 95% CI). We used the colonization estimates to simulate the effective reproduction number R through a Monte Carlo technique.

RESULTS:

Based on data from 9 eligible studies that met the specified criteria and included 1,371 subjects, we found that 14.8% (95%CI 7.6%-24.0%) of LTCF residents are asymptomatic carriers of toxigenic C. difficile. Colonization estimates were significantly higher in facilities with prior CDI outbreak (30.1% vs. 6.5%, p = 0.01). Patient history of CDI (OR 6.07; 95% CI 2.06-17.88; effect derived from 3 studies), prior hospitalization (OR 2.11; 95% CI 1.08-4.13; derived from 3 studies) and antimicrobial use within previous 3 months (OR 3.68; 95% CI 2.04-6.62; derived from 4 studies) were associated with colonization. The predicted colonization rate at admission was 8.9%.

CONCLUSION:

Asymptomatic carriage of toxigenic C. difficile represents a significant burden in LTCFs and is associated with prior CDI outbreaks in the facility, a history of CDI, prior hospitalization and antimicrobial use. These findings can impact infection control measures at LTCFs.

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

http://www.ncbi.nlm.nih.gov/pubmed/25707002

C. diff. Research and Development Community October 2015

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Here is the latest from the Clostridium difficile research community

 

 

 

Serum 25-hydroxyvitamin D levels are not associated with adverse outcomes in                        Clostridium difficile infection

Clostridium difficile infection (CDI) is a significant source of healthcare-associated morbidity and mortality. This study investigated whether serum 25-hydroxyvitamin D is associated with adverse outcomes from CDI. Patients with CDI were prospectively enrolled. Charts were reviewed and serum 25-hydroxyvitamin D was measured. The primary outcome was a composite definition of severe disease: fever (temperature >38°C), acute organ dysfunction, or serum white blood cell count >15,000 cells/µL within 24-48 hours of diagnosis; lack of response to therapy by day 5; and intensive care unit admission; colectomy; or death within 30 days. Sixty-seven patients were included in the final analysis. Mean (±SD) serum 25-hydroxyvitamin D was 26.1 (±18.54) ng/mL. Severe disease, which occurred in 26 (39%) participants, was not associated with serum 25-hydroxyvitamin D [odds ratio (OR) 1.00; 95% confidence interval (CI) 0.96-1.04]. In the adjusted model for severe disease only serum albumin (OR 0.12; 95%CI 0.02-0.64) and diagnosis by detection of stool toxin (OR 5.87; 95%CI 1.09-31.7) remained independent predictors. We conclude that serum 25-hydroxyvitamin D is not associated with the development of severe disease in patients with CDI.

For full article click on the link below:

http://www.pagepress.org/journals/index.php/idr/article/view/5979

 

Clostridium difficile is a Gram-positive spore-forming pathogen and a leading cause of nosocomial diarrhea. C. difficile infections are transmitted when ingested spores germinate in the gastrointestinal tract and transform into vegetative cells. Germination begins when the germinant receptor CspC detects bile salts in the gut. CspC is a subtilisin-like serine pseudoprotease that activates the related CspB serine protease through an unknown mechanism. Activated CspB cleaves the pro-SleC zymogen, which allows the activated SleC cortex hydrolase to degrade the protective cortex layer. While these regulators are essential for C. difficile spores to outgrow and form toxin-secreting vegetative cells, the mechanisms controlling their function have only been partially characterized. In this study, we identify the lipoprotein GerS as a novel regulator of C. difficile spore germination using targeted mutagenesis. A gerS mutant has a severe germination defect and fails to degrade cortex even though it processes SleC at wildtype levels. Using complementation analyses, we demonstrate that GerS secretion, but not lipidation, is necessary for GerS to activate SleC. Importantly, loss of GerS attenuates the virulence of C. difficile in a hamster model of infection. Since GerS appears to be conserved exclusively in related Peptostreptococcaeace family members, our results contribute to a growing body of work indicating that C. difficile has evolved distinct mechanisms for controlling the exit from dormancy relative to B. subtilis and other spore-forming organisms.

For full article click on the link below:

http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1005239

 

XBiotech  the world’s leading developer of next-generation True Human™ therapeutic antibodies, announced today the launch of a research and development program to develop a first-in-class oral monoclonal antibody against Clostridium difficile (C. difficile) infection. Using its proprietary True Human technology, the Company has begun screening human blood samples from donors to identify and clone a therapeutic antibody candidate from individuals with natural immunity to C. difficile infection.

For full article click on the link below:

In a 1-year survey at a university hospital we found that 20·6% (81/392) of patients with antibiotic associated diarrohea where positive for C. difficile. The most common PCR ribotypes were 012 (14·8%), 027 (12·3%), 046 (12·3%) and 014/020 (9·9). The incidence rate was 2·6 cases of C. difficile infection for every 1000 outpatients.
For full article click on the link below:

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=10011117&fileId=S0950268815002459

Microbiota Changes Predict Treatment Failure
Infection with C. difficile is associated with several adverse outcomes including treatment failure (5% to 35%) but researchers do not know what clinical factors can predict this failure.

Reporting at the American College of Gastroenterology Scientific Meeting in Honolulu, a Mayo Clinic team of researchers looked at which gut microbiota signatures might be useful in determining whether patients will get better.

They defined treatment failure as a non-response to treatment with vancomycin for four days or metronidazole for five days. They looked at 889 patients with primary C. dif in infection (CDI) of whom 60.2% were women and the median age was 54 years. Of these 7% had severe CDI, 70.5% had been treated with metronidazole, 23.8% with vancomycin, and 5.6% with a combination.

Overall 12.5% failed treatment and the rates were similar with each drug.

The researchers looked at clinical factors that might have predicted the failures–age, sex, obesity, prior antibiotic use, and other factors. They found no correlation between having those factors and failing treatment. They did find that patients who responded to treatment had higher quantities of certain bacteria, for instance Faecalibacterium and Bacteroides.

Conversely, the patients who failed treatment had more Streptococcus and Clostridium.

The authors suggest that analyzing these changes in microbiota could be useful. “Gut microbiota signatures may be used to predict treatment response in the absence of reliable clinical predictors,” said Sahil Khanna, MBBS, M S in presenting the study.

For full article click on the link below:

C. diff. Research and Development – August 2015

Microbiota and Subsequent Effects on Colonization Resistance against Clostridium difficile

Alyxandria M. Schubert, Hamide Sinani, Patrick D. Schloss

To read this paper in its entirety :

http://mbio.asm.org/content/6/4/e00974-15.short?rss=1&ssource=mfr

The gastrointestinal tract harbors a complex community of bacteria, known as the microbiota, which plays an integral role preventing its colonization by gut pathogens. This resistance has been shown to be crucial for protection against Clostridium difficile infections (CDI), which are the leading source of hospital-acquired infections in the United States. Antibiotics are a major risk factor for acquiring CDI due to their effect on the normal structure of the indigenous gut microbiota. We found that diverse antibiotic perturbations gave rise to altered communities that varied in their susceptibility to C. difficile colonization. We found that multiple coexisting populations, not one specific population of bacteria, conferred resistance. By understanding the relationships between C. difficile and members of the microbiota, it will be possible to better manage this important infection.

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The spore-associated protein BclA1 affects the susceptibility of animals to colonization and infection by Clostridium difficile

To read this paper in its entirety :

http://onlinelibrary.wiley.com/doi/10.1111/mmi.12611/abstract

The paper shows that so-called “hypervirulent” strains of C. difficile, such as the 027 ribotype strains, are actually less infectious than the existing strains of C. difficile carried in humans and animals. We were able to show this by characterizing one gene of C. difficile that encodes the BclA1 protein. BclA1 is involved in the early stages of colonization and its presence enables spores of C. difficile to colonise the host. When this protein is removed or truncated the ability of spores to colonise is much reduced. This then raises the question of how hypervirulent strains are more efficient at infecting a host, in other words, how they can be more virulent. The answer is probably the hypervirulent strains are able to produce more toxins. This work raised the concept that C. difficile is similar to influenza. For example, with influenza the most infectious influenza strains  do not normally cause fatality (ie, the seasonal flu strains). On the other hand, the pandemic strains (avian influenza) are not very infectious (that is, they spread poorly) yet when they do infect they cause a dangerous infection more likely to lead to fatality. C. difficile we reason behaves in a similar way, the hypervirulent strains are poorly infectious yet cause a more potent infection while highly infectious strains cause a less potent infection. We plan to use this knowledge to type new isolates of C. difficile and assess their risk to humans.

Professor Simon M. Cutting
School of Biological Sciences,
Bourne Laboratories, 4-26,
Royal Holloway, University of London
Egham,
Surrey TW20 OEX
UK

C. diff. cases higher in the Spring according to a study conducted by researchers at the University of Texas at Austin

People may be more likely to get infected with the sometimes deadly gut infection called “C. diff” during the spring, according to a new study.

Researchers analyzed information from people who were discharged from U.S. hospitals between 2001 and 2010. During this time period, about 2.3 million people were released from a hospital following an infection with Clostridium difficile, which can cause severe diarrhea, and frequently comes back after treatment.

In the spring, there were about 62 cases of C. difficile for every 10,000 people discharged from the hospital, the study found.

In winter and summer, there were 59 C. difficile cases per 10,000 people discharged from the hospital, and the lowest rate was seen in the fall, when there were 56 C. difficile cases per 10,000 hospital discharges.

Most cases of C. difficile occur after people take antibiotics, which disturb the normal balance of gut bacteria, giving harmful bacteria the chance to overgrow. It’s possible that the rates of C. difficile infection are the highest in the spring because people use more antibiotics during the winter months to treat respiratory infections, the researchers said. There can be a one- to two-month lag between the time a person takes antibiotics, or antimicrobials, and when he or she develops a C. difficile infection.

The new finding “emphasizes the importance of antimicrobials’ use as a risk factor” for                   C. difficile infections, the researchers said. The results also underscore the need to better control infections and use antibiotics only when they are needed,” particularly during high-risk seasons and in high-risk areas, the researchers wrote.

The study also found that, over the 10-year study period, the rates of C. difficile infection were the highest in the Northeast, where the overall rate was 80 cases per 10,000 hospital discharges, followed by the Midwest (64 cases per 10,000 hospital discharges), the South (50 cases per 10,000 hospital discharges) and the West (48 cases per 10,000 hospital discharges).

These regional differences in C. difficile could be partly due to differences in the number of older adults in each area, with the Northeast possibly having a higher proportion of older adults, the researchers said. Older adults are at increased risk for C. difficile infection. In fact, the overall rate of C. difficile infections during the study was 160 cases per 10,000 hospital discharges among adults age 65 and older, compared with 35 cases per 10,000 discharges in adults under 65 and 12 cases per 10,000 discharges in children.

“Our findings indicate the need for additional resources when and where health care burdens are highest,” the researchers said.

The study, conducted by researchers at the University of Texas at Austin, is published in the May issue of the American Journal of Infection Control.

 

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

http://news.yahoo.com/deadly-gut-bacteria-infections-peak-spring-145430313.html;_ylt=A0LEVxPSvkNV1ooA0MFXNyoA;_ylu=X3oDMTEza2t0ajNjBGNvbG8DYmYxBHBvcwMxBHZ0aWQDVklQNTY0XzEEc2VjA3Nj