Monash University researchers have led an international team of scientists to a significant breakthrough in the fight against a potentially deadly superbug. (Credit: Image courtesy of Monash University)
Retrieved June 3, 2009, from http://www.sciencedaily.com /releases/2009/03/090302115753.htm — – An international team of scientists, led by Monash University researchers, has uncovered the workings of a superbug that kills elderly hospital patients worldwide — a discovery that has the potential to save lives and health care systems billions of dollars each year.
The research, published March 2 in the journal Nature, unravels ways to genetically modify the bacterium Clostridium difficile and solves the mystery surrounding its toxicity.
Professor Julian Rood from the Department of Microbiology and lead author, microbiologist Dr Dena Lyras, made a major scientific breakthrough which allowed mutants of the superbug to be made. They then identified which of two suspected toxic proteins was essential for the bacterium to cause severe disease.
“Contrary to previously accepted scientific belief, our results show that toxin B, which was considered the less important toxin is actually the toxin that causes disease,” Professor Rood said.
“This discovery will lead to new methods for the control and prevention of this disease”.
Professor Rood and Dr Lyras have been working toward this result for more than a decade. Dr Lyras said strains of Clostridium difficile are found in almost every hospital in Australia.
“It is the major cause of diarrhoea in hospital patients undergoing antibiotic therapy. The antibiotics destroy the ‘good’ bacteria in the gut, allowing a ‘bad’ bacterium to grow in the colon, where it causes a chronic bowel infection that is very difficult to treat,” Dr Lyras said.
“The disease produces two types of toxins, known as A and B. Worldwide research has tended to focus on these purified toxins in isolation from the bug. This only resulted in part of the story being told. We took a big picture approach and through genetic modification of the bug, together with infection studies with our US collaborators, we were able to see the whole picture,” Dr Lyras said.
Statistics show that in the US, more people die from Clostridium difficile infections than all other intestinal infections combined, with most deaths involving patients aged 65 years or over. The disease is believed to have contributed to more than 8,000 deaths in the UK in 2007. A less aggressive form of the bacteria is present in Australia but statistics in 1995-dollars show the cost of managing the disease to be around $1.25 million dollars per hospital, per year.
Their research lays the foundation to find better ways to treat the superbug.
“We are now beginning to understand the workings of the superbug, which allows us to work on treatments for it. We are confident our research will pave the way for future drugs to try to wipe out this disease. I can’t put a time frame on how quickly drugs could be developed, but we’re certainly on that road to discovery,” Dr Lyras said.
Adapted from materials provided by Monash University.
difficile colonies on a blood agar plate
Clostridium difficile (Greek kloster (κλωστήρ), spindle, and Latin difficile, difficult), also known as “CDF/cdf”, or “C. diff”, is a species of Gram-positive bacteria of the genus Clostridium. Clostridia are anaerobic, spore-forming rods (bacillus). C. difficile is the most serious cause of antibiotic-associated diarrhea (AAD) and can lead to pseudomembranous colitis, a severe infection of the colon, often resulting from eradication of the normal gut flora by antibiotics. The C. difficile bacteria, which naturally reside in the body, become overgrown: The overgrowth is harmful because the bacterium releases toxins that can cause bloating, constipation, and diarrhea with abdominal pain, which may become severe. Latent symptoms often mimic some flu-like symptoms. Discontinuation of causative antibiotic treatment is often curative. In more serious cases, oral administration of metronidazole or vancomycin is the treatment of choice. Relapses of C. difficile AAD have been reported in up to 20% of cases.
Clostridia are motile bacteria that are ubiquitous in nature and are especially prevalent in soil. Under the microscope, clostridia appear as long, irregularly (often “drumstick” or “spindle”) shaped cells with a bulge at their terminal ends. Under Gram staining, Clostridium difficile cells are Gram-positive and show optimum growth on blood agar at human body temperatures in the absence of oxygen. When stressed, the bacteria produce spores, which tolerate extreme conditions that the active bacteria cannot tolerate.
The first complete genome sequence of a Clostridium difficile strain was first published in 2006 by the Sanger Centre, UK. This was of the C. difficile strain 630, a virulent and multidrug-resistant strain. Researchers at McGill University in Montreal, Quebec, sequenced the genome of the highly virulent Quebec strain of C. difficile in 2005 using ultra-high-throughput sequencing technology. The tests involved doing 400,000 DNA parallel sequencing reactions which took the bacterium’s genome apart and reassembled it so it could be studied
UCF Associate Professor William Self works in his lab with student and co-author Sarah Jackson-Rosario. (Credit: Jacque Brund)
University of Central Florida (2009, June 1). Newly Discovered Reactions From An Old Drug May Lead To New Antibiotics. ScienceDaily – A mineral found at health food stores could be the key to developing a new line of antibiotics for bacteria that commonly cause diarrhea, tooth decay and, in some severe cases, death.
The trace mineral selenium is found in a number of proteins in both bacterial cells and human cells called selenoproteins. University of Central Florida Associate Professor William Self’s research shows that interrupting the way selenoproteins are made can halt the growth of the super bug Clostridium difficile and Treponema denticola, a major contributor to gum disease.
Infections of Clostridium difficile (commonly known as C-diff) lead to a spectrum of illnesses ranging from severe diarrhea to colitis, which can cause death. It’s a life-threatening problem in hospitals and nursing homes worldwide, and the number of cases is on the rise. There are an estimated 500,000 cases per year in the United States alone. Between 15,000 to 20,000 people die each year while infected with this superbug. Treponema denticola is one of leading causes of gum disease and costs individuals thousands of dollars in dental care each year.
Self’s findings are published in the May and June editions of the Journal of Biological Inorganic Chemistry and the Journal of Bacteriology. The National Institutes of Health and the Florida Department of Health funded the research, which was conducted at UCF during the past three years.
“It’s the proof of principle that we are excited about,” Self said from his research lab at UCF. “No one has ever tried this approach, and it could potentially be a source for new narrow spectrum antibiotics that block bacteria that require selenium to grow.”
The key discovery occurred when the team found that the gold drug Auranofin, used to treat arthritis, impacted selenium’s metabolism process. The chemical reaction changes the selenium, which prevents bacteria from using it to grow. Auranofin is an FDA-approved gold salt compound that is used to control inflammation and is already known to inhibit the activity of certain selenoproteins. Since certain bacteria, such as C. difficile, require selenoproteins for energy metabolism, the drug acts as a potent antimicrobial halting the growth of the bacteria.
The initial studies with C. difficile led to studies with T. denticola, known for several years to require selenium for growth. While testing the gold salt, Self’s group also uncovered another surprise; the stannous salts found in many antimicrobial toothpastes in the form of stannous fluoride also inhibited the synthesis of selenoproteins. Previous independent research had already established that stannous salts are more effective at preventing tooth decay and inhibiting growth of T. denticola, but the mechanism of this inhibition of growth was not yet known. These findings could lead to new approaches to preventing gum disease.
“No one has tried to block the metabolism of selenium before as a therapeutic approach,” Self said. “That’s what’s new and exciting and could lead to a whole host of other possibilities, including a better understanding of how the gold salt works for arthritis.”
Self said more research is needed, and he already has another grant proposal before the NIH that would move his research forward.
Three-dimensional rendering of a biofilm. (Credit: Image courtesy of Texas A&M University)
Call it advanced warfare on the most elemental of levels.
Texas A&M University (2009, June 4). How ‘Invading’ Bacteria Can Integrate Captured DNA Into Own Genetic Makeup. ScienceDaily – Call it advanced warfare on the most elemental of levels.
Researchers at Texas A&M University’s Artie McFerrin Department of Chemical Engineering have discovered how certain types of bacteria integrate the DNA that they have captured from invading enemies into their own genetic makeup to increase their chances of survival.
To be more accurate, the genetic material isn’t really captured as much as it is simply utilized after it’s injected into the bacteria by an invading virus, says Professor Thomas K. Wood, who along with colleagues Xiaoxue Wang and Younghoon Kim has published the findings in Nature’s 2009 International Society for Microbial Ecology Journal.
Wood’s findings shed light on a millions-of-years-old battle between bacteria and bacteria-eating viruses known as “phages.” Locked in an epic struggle, the two life forms, Woods explains, are constantly developing new ways to win the war. One such approach undertaken by a phage is to attach to a bacterial cell and, using a syringe-like tail apparatus, inject its genetic material into the bacterial cell. Once inside, the phage replicates itself and eventually exits the cell to find new bacteria to infect.
But as is the case with men, the best-laid plans of phages can also go astray.
Examining E. coli bacteria, Wood found that the bacteria developed a means of not allowing the phage to replicate and leave the cell of its own volition. Once the phage was effectively “captured,” the bacteria incorporated the phage’s DNA material into its own chromosomes. This new diverse blend of genetic material, Wood says, has helped the bacteria not only overcome the phage but also flourish at a greater rate than similar bacteria that have not incorporated the phage DNA.
“The bacteria are alive and doing well, and in fact the bacteria are doing better because it captured its enemy,” Wood said. “Our research shows that if these bacteria didn’t have this particular set of 25 genes that belonged to the old phage it wouldn’t be able to grow as fast. If you removed the phage remnant, the bacteria grows five times slower on some carbon sources.”
This distinct advantage is helping scientists understand why bacteria carry about 10-20 percent of genes that aren’t their own. Simply put, carrying the virus DNA allows bacteria to increase their chances of survival by producing diverse progeny – something Wood says is extremely important when the bacteria choose to move to a new environment through a process known as dispersal.
Dispersal occurs, Woods says, when the bacterium can no longer glean the nutrients it needs from its surroundings or when other environmental conditions, such as temperature, have become unfavorable. Wood found that through an elaborate regulation method, the bacteria are able to retain the virus DNA or expel it. It’s an interesting trade off, as retaining the virus DNA helps the bacteria grow faster but reduces its motility, which is needed when seeking out new environments, Wood explains.
Further exploring this dynamic, Wood and his research group were able to link this regulation process to the formation of bacterial communities called biofilms.
A biofilm, Wood says, is a protective, adhesive slime created by bacteria that have joined together to form a community and reap the benefits of a “strength-in-numbers” approach. Biofilms can grow on a variety of living and nonliving surfaces, including submerged rocks, food, teeth (as plaque) and biomedical implants such as knee and hip replacements.
The National Institutes of Health estimate that about 90 percent of infections in humans are caused by biofilms, and the Centers for Disease Control estimate biofilm to be present in 65 percent of hospital-acquired (nosocomial) infections. Biofilms typically are the cause of fatal infections that develop post surgery. More commonly, they are the source of persistent ear infections among children.
In addition to finding that biofilm formation relies heavily on virus genes present within the bacteria, Wood’s research has shown the mechanism for how this takes place. A protein within the bacterium called Hha has the ability to control whether virus genes are kept within the bacterium or jettisoned. When Hha is basically “turned on,” the bacteria expel the virus genes, opting for motility over the ability to form biofilms. Likewise, when Hha is not expressed, the bacteria move slower but grow biofilms at a much faster rate, Wood explains.
It’s a finding that could impact everything from health care to research into alternative fuel production.
“If we can understand how biofilms are formed, we can begin to manipulate forming them where we want and getting them to not form where we don’t want them,” Wood says. “We have found a regulator – this Hha – that controls the genes related to biofilm formation. Now we can begin to envision ways to turn on that Hha gene if we want to get rid of biofilms, and that is what we are working on. That’s the long-term goal – as engineers to make biofilms where we want them.
“For example, if we want to remediate soil, we’d form a biofilm on the roots of plants, plant the tree, and wherever the tree root goes we clean the soil. That’s a beneficial biofilm. If I want to make hydrogen with E. coli, I’ll probably want to do it in a biofilm, so I would want to promote the growth of the biofilm.
“We’re one of the first labs in the world that has begun to not only try to understand how biofilms form but to control them.”
Xiaoxue Wang, Younghoon Kim and Thomas K Wood. Control and benefits of CP4-57 prophage excision in Escherichia coli biofilms. The ISME Journal, 2009; DOI: 10.1038/ismej.2009.59
University of Nottingham, Retrieved June 4, 2009, from http://www.sciencedaily.com /releases/2009/01/090119142313.htm – Scientists at The University of Nottingham are leading a major European study to unravel the genetic code of one of the most lethal strains of hospital acquired infections.
The 3 million euro, three-year study will use gene knock-out technology developed in Nottingham to study the function of genes in a ‘super’ strain of the bacteria Clostridium difficile to discover why it causes more severe disease, kills more people, is harder to eradicate and more resistant to antibiotics.
It is hoped that the HYPERDIFF study, which involves partners from the UK, Slovenia, Italy, France, The Netherlands and Germany and is funded with a grant from the European Community, will lead to better tests to diagnose ‘super’ strains of C.difficile, more effective treatments and, possibly, even a vaccine to protect against the disease.
Since the turn of the new millennium there has been a dramatic increase in the incidence of C.difficile. Currently the most frequently occurring healthcare associated infection, last year it killed more than seven times as many people in the UK as MRSA. Reasons for this increase may include improvements in reporting procedures, the increasing age of the population as the elderly are especially vulnerable, lower standards of hygiene and overcrowding on hospital wards.
However, a further significant factor has been the arrival in Europe of so-called ‘hypervirulent’ strains such as ribotype 027, which are responsible for more severe disease and are more difficult to treat.
Currently, scientists know that the bacteria cause disease by sticking to epithelial cells of the gut lining and releasing two toxins that damage cells leading to the tell-tale symptom of severe diarrhoea. However, there is very little known about the ways in which the bacteria operate and why the strain should be more severe than its less virulent cousins.
Leading the study, Professor Nigel Minton in The University of Nottingham’s School of Molecular Medical Sciences, said: “These hypervirulent organisms seem to be taking over as the dominant strain in outbreaks and, worryingly, there are only two antibiotics which are still effective against them. There is a very real danger that total resistance may arise, and if that happens then this will become an extremely serious problem.
“The idea behind the study is that we investigate the genomes of the hypervirulent strains and identify their differences to the so-called standard strains. In this way, we should get a clearer picture of the whole range of factors involved in its spread and the way in which it causes disease.”
During the three-year study, scientists at Nottingham will use a technology called ClosTron to produce mutant versions of the hypervirulent strains. They will knock out genes one by one and then compare the mutant version to the standard organism to assess the function of each cell.
The project will also investigate whether pets and other domesticated animals are carriers of the bacteria and what effect this may have had on the rise of C.difficile as a community acquired infection.
American Chemical Society (2009, June 3). Bird Flu Virus Remains Infectious Up To 600 Days In Municipal Landfills. ScienceDaily – Amid concerns about a pandemic of swine flu, researchers from Nebraska report for the first time that poultry carcasses infected with another threat – the “bird flu” virus – can remain infectious in municipal landfills for almost 2 years.
Shannon L. Bartelt-Hunt and colleagues note that avian influenza, specifically the H5N1 strain, is an ongoing public health concern. Hundreds of millions of chickens and ducks infected with the virus have died or been culled from flocks worldwide in efforts to control the disease. More than 4 million poultry died or were culled in a 2002 outbreak in Virginia, and the carcasses were disposed of in municipal landfills. Until now, few studies have directly assessed the safety of landfill disposal.
“The objectives of this study were to assess the survival of avian influenza in landfill leachate and the influence of environmental factors,” says the report. The data showed that the virus survived in landfill leachate – liquid that drains or “leaches” from a landfill – for at least 30 days and up to 600 days. The two factors that most reduced influenza survival times were elevated temperature and acidic or alkaline pH. “Data obtained from this study indicate that landfilling is an appropriate method for disposal of carcasses infected with avian influenza,” says the study, noting that landfills are designed to hold material for much longer periods of time.
•1. Graiver et al. Survival of the Avian Influenza Virus (H6N2) After Land Disposal. Environmental Science & Technology, 2009; 43 (11): 4063 DOI: 10.1021/es900370x
Marmoset monkeys engineered to carry the gene for green fluorescent protein. The soles of the animals’ feet glow green when shown under UV light.
Courtesy of E. Sasaki et al., 2009
The genetic-engineering primates could lead to better models for studying disease.
MIT Technology Review, June 3, 2009, by Emily Singer — Last month in Japan, a very special marmoset monkey was born–one who inherited from his parents not only their marmoset DNA, but also a jellyfish gene for green fluorescent protein (GFP) that makes both the animal and his parents glow green under fluorescent light. The monkey parents aren’t the first primates to fluoresce, but they are the first to pass a genetically engineered trait to their offspring. Scientists hope to use the approach to create animal models of neurological diseases, such as Parkinson’s, which cannot be adequately reproduced in rodents–the typical subjects of genetic engineering.
“The birth of this transgenic marmoset baby is undoubtedly a milestone,” write Gerald Schatten and Shoukhrat Mitalipov in a piece accompanying the paper, published today in the journal Nature. Scientists have previously created a menagerie of transgenic animals, including rats, rabbits, pigs, cows, cats, dogs, and even monkeys (in one study, scientists created monkeys that genetically mimic Huntington’s disease), but “no study has shown transmission of foreign DNA to gametes–the sperm and egg–which is essential for the generation of transgenic offspring. These offspring could then be bred to create transgenic-primate strains,” they add.
The ability to genetically engineer primates is essential for creating more-accurate animal models of human diseases, especially neurological ones. For example, Schatten and Mitalipov say,
Mice engineered to express the cystic fibrosis gene, for example, do not develop the lung problems that typify this disorder . . . Disorders of higher brain function, such as Alzheimer’s disease, are especially challenging to reproduce in rodents, and here, as with many other diseases, it is our closest animal relatives–the non-human primates–that offer potentially invaluable biological models.
To create the transgenic monkeys, researchers injected viruses carrying the gene for GFP into 91 marmoset embryos. Eighty healthy transgenic embryos were then transplanted into surrogate mothers, who birthed five glowing offspring. Three glowing second-generation marmosets have been born since April.
Source: QS Quacquarelli Symonds (www.topuniversities.com). With permission.
Copyright © 2004-2008 QS Quacquarelli Symonds Ltd.
THE – QS World University Rankings 2008
The Complete Rankings
THE – QS World University Rankings results –The Times Higher Education – QS World University Rankings identified these to be the world’s top 100 universities in 2008. These institutions represent 20 countries with Israel represented for the first time. Whilst North America dominates with 42 universities, Europe and Asia Pacific are well represented with 36 and 22 respectively.
Source: QS Quacquarelli Symonds (www.topuniversities.com). With permission.
Copyright © 2004-2008 QS Quacquarelli Symonds Ltd.