Science Current Events | Science News | Brightsurf.com
 

'Gut'-throat competition: Research on digestive tract bacteria yields surprising findings

May 11, 2012
ANN ARBOR, Mich. - From tiny villages in developing nations to suburban kitchens in the United States, dangerous strains of E. coli bacteria sicken millions of people each year - and kill untold numbers of children.

Now, new research from the University of Michigan Health System gives scientists a better understanding of what is going on in the diarrhea-wracked guts of its victims, and what might be done to prevent or treat it.

Specifically, they show that the bacteria that usually live in our digestive tracts compete against invading bacteria such as E. coli to help our bodies fend them off.

They also show that the invaders depend on certain genes to gain a temporary upper hand in that battle -- just long enough to reproduce and cause the symptoms that expel their offspring from the body so they can find a new host.

The findings, published in journal Science on its Science Express website, point to potential ways to prevent or treat infections by enterohemorrhagic or enteropathogenic E. coli. Those are the types that can lurk in undercooked ground beef, unpasteurized milk, untreated drinking water, and contaminated produce - and that can cause diarrhea and other symptoms that sicken adults and can kill vulnerable children.

"More than 1,000 species of bacteria live in our guts, in a symbiotic population called the microbiota," says Gabriel Nunez, M.D., the U-M pathologist who led the research team. "These results show that these bacteria, also called commensals, compete with pathogens (disease-causing bacteria) in a previously unappreciated way - and that the pathogens use a specific set of genes to temporarily outcompete commensals before leaving the body. Understanding this gives us potential targets for prevention and treatment."

For instance, since the research shows that harmful bacteria compete with commensal bacteria for certain nutrients that they need to survive, selectively removing some nutrients and boosting others might help. So might a more targeted use of antibiotics when treating patients who are battling an E. coli infection.

Nunez and first author Nobuhiko Kamada, Ph.D., a postdoctoral fellow, made the findings by studying mice that they infected with C. rodentium - the rodent equivalent of harmful E. coli. The study included specially bred germ-free mice that lacked all the "good" gut bacteria that normal mice and humans harbor.

Both Nunez and Kamada are members of the U-M Medical School's Department of Pathology and the U-M Comprehensive Cancer Center, and the work fits into their broader investigations of how inflammation and immunity play a role in the body's response to cancer as well as infections.

Fittingly, Nunez holds the Paul H. de Kruif Professorship in Pathology, named for the U-M graduate who wrote Microbe Hunters, a pivotal 1926 book on the history of infectious disease research.

In the new paper, the team adds a new chapter to the understanding of how pathogenic bacteria gain a foothold in the gut - literally - by turning on virulence genes that allow them to attach to the cells that line the digestive tract.

This attaching-and-effacing activity, as it is called, allows the disease-causing bacteria to intimately adhere to the cells that line the gut, consume nutrients and reproduce, out-competing the natural gut bacteria. But this comfortable niche only lasts a few days or weeks, during which the host's gut gets more inflamed as the immune system responds to the insult. Diarrhea, sometimes containing blood that leaks from the gut lining, results.

And that, the researchers find, is when the pathogens stop expressing the virulence genes that allowed them to gain their upper hand. They unhitch from the gut lining, mixing in with the commensal bacteria in the open center (lumen) of the gut, and fighting for what food they can find.

While this return to competition means that some of them die, enough of them survive to be expelled in the feces. And if good sanitation systems aren't in place, the bacterial offspring have a good chance of finding a new host to take a toll on.

Better sanitation throughout the world can prevent infections in the first place, says Nunez. But when infection by pathogenic bacteria occurs, a better understanding of the way they interact with our native bacteria could eventually help save lives.

Nunez's team is working with the lab of U-M microbiologist and co-author Eric Martens, Ph.D., to screen different sugars that, if withheld or enhanced in the diet, might weaken the pathogens' effects. That could lead to a better understanding of how children and weak adults in developing nations should be fed while being treated for infection.

The University of Michigan has applied for patent protection, and is in the process of looking for commercialization partners to help bring the technology to market.

###

The research was supported by grants from the National Institutes of Health, CONACyT, CIHR, the Uehara Memorial Foundation, and the Crohn's and Colitis Foundation of America. Several specialized core research facilities at the U-M Medical School were used in the work, including the Germ-free Animal Core, the Microscopy and Image Analysis Laboratory, and the Center for Molecular Imaging.

Reference: Science Express - Regulated Virulence Controls the Ability of a Pathogen to Compete with the Gut Microbiota - Manuscript Number: science.1222195

University of Michigan Health System


Related Pathogenic Bacteria Current Events and Pathogenic Bacteria News Articles


Toxin from salmonid fish has potential to treat cancer
Pathogenic bacteria develop killer machines that work very specifically and highly efficiently. Scientists from the University of Freiburg have solved the molecular mechanism of a fish toxin that could be used in the future as a medication to treat cancer.

New colon cancer culprit found in gut microbiome
Changes in the gut bacteria of colon cancer patients indicate that some virulent bacteria could be linked to the progression of the disease, according to research published in the open access journal Genome Medicine.

Unique bacterial fingerprint identified in systemic sclerosis
The results of a study presented today at the European League Against Rheumatism Annual Congress (EULAR 2015) Press Conference showed that people with systemic sclerosis (SSc) have a unique bacterial signature in their colon, when compared with healthy people.

Bacteria shown to suppress their antibiotic-resistant cousins
Researchers studying a dangerous type of bacteria have discovered that the bacteria have the ability to block both their own growth and the growth of their antibiotic-resistant mutants.

Stanford scientists find genetic signature enabling early, accurate sepsis diagnosis
Investigators at the Stanford University School of Medicine have identified a pattern of gene activity that could help scientists create a blood test for quickly and accurately detecting whether patients are experiencing a deadly immune-system panic attack.

Bacteria research opens way for new antibiotics
University of Adelaide researchers have discovered a target for the development of completely new antibiotics against disease-causing bacteria.

A CRISPR antiviral tool
Emory scientists have adapted an antiviral enzyme from bacteria called Cas9 into an instrument for inhibiting hepatitis C virus in human cells.

Could maple syrup help cut use of antibiotics?
A concentrated extract of maple syrup makes disease-causing bacteria more susceptible to antibiotics, according to laboratory experiments by researchers at McGill University.

How Salmonella survives the macrophage's acid attack
Macrophages destroy bacteria by engulfing them in intracellular compartments, which they then acidify to kill or neutralize the bacteria.

New mechanisms of 'social networking' in bacteria
Bacteria have traditionally been viewed as solitary organisms that "hang out on their own," says molecular biologist Kevin Griffith of the University of Massachusetts Amherst.
More Pathogenic Bacteria Current Events and Pathogenic Bacteria News Articles

Laboratory Guide for Identification of Plant Pathogenic Bacteria

Laboratory Guide for Identification of Plant Pathogenic Bacteria
by N. W. Schaad (Editor), J. B. Jones (Editor), Wesley Chun (Editor)


Book by

Plant Pathogenic Bacteria: Genomics and Molecular Biology

Plant Pathogenic Bacteria: Genomics and Molecular Biology
by Robert W. Jackson (Editor)


Bacteria pathogenic for plants are responsible for devastating losses in agriculture. The use of antibiotics to control such infections is restricted in many countries due to worries over the evolution and transmission of antibiotic resistance. The advent of genome sequencing has enabled a better understanding, at the molecular level, of the strategies and mechanisms of pathogenesis, evolution of resistance to plant defense mechanisms, and the conversion of non-pathogenic into pathogenic bacteria. In this book, internationally acclaimed experts review the most important developments, providing an invaluable up-to-date summary of the molecular biology and genomics of plant pathogenic bacteria. The book opens with two chapters on bacterial evolution, diversity, and taxonomy - topics that...

Bacteria: A Very Short Introduction (Very Short Introductions)

Bacteria: A Very Short Introduction (Very Short Introductions)
by Sebastian G.B. Amyes (Author)


Bacteria form a fundamental branch of life. They are the oldest forms of life and the most prolific of all living organisms, inhabiting every part of the Earth's surface, its ocean depths, and even such inhospitable places as boiling hot springs. In this Very Short Introduction, bacteriologist Sebastian Amyes explores the nature of bacteria, their origin and evolution, bacteria in the environment, and bacteria and disease. Amyes discusses some of the major infections caused by bacteria-bacteria causes pneumonia, diphtheria, cholera, and many other diseases-and shows how these pathogens avoid the defences of the human body. But the book looks at all aspects of bacteria, not just the negative side, stressing the key benefits of bacteria, which have been harnessed to preserve food, dispose...

Bacteria: The Benign, the Bad, and the Beautiful

Bacteria: The Benign, the Bad, and the Beautiful
by Trudy M. Wassenaar (Author)


A comprehensive, reader-friendly introduction to the world of bacteria

When most people hear the word "bacteria" they think of food poisoning; infections; and acute, debilitating, or fatal diseases. Yet, while E. coli, strep, and other bacterial pathogens certainly cause their share of misery in the world, they are only a tiny portion of a vast universe of microorganisms—the most basic of life forms. Without them, nothing else could live or grow on Planet Earth. Bacteria: The Benign, the Bad, and the Beautiful introduces you to this diverse, microscopic world and explains the fundamental microbiological concepts you need to explore the life and behavior of bacteria. Even if you have no previous background in the subject, the book's clear, jargon-free language tells you...

Stress Response in Pathogenic Bacteria (Advances in Molecular and Cellular Microbiology)

Stress Response in Pathogenic Bacteria (Advances in Molecular and Cellular Microbiology)
by Stephen Kidd (Editor)


The ability of pathogenic bacteria to adapt to various chemical, biochemical and physical conditions within the human host and their ability to respond to stresses generated in these environments is a central feature of infectious diseases and the outcome of bacterial infection. This book covers the key aspects of this rapidly developing field, including the generation of stresses by the host immune system, bacterial response to reactive chemicals, and adaptation to environmental conditions of anatomical niches such as the gut, mouth and urogenital tract. It also addresses the increasing importance of different metal ions in the pathogenesis and survival of specific bacteria. With chapters by active research experts in the field, the book provides a comprehensive outline of the current...

Herbal Antibiotics, 2nd Edition: Natural Alternatives for Treating Drug-resistant Bacteria

Herbal Antibiotics, 2nd Edition: Natural Alternatives for Treating Drug-resistant Bacteria
by Stephen Harrod Buhner (Author)


Antibiotic-resistant infections are alarmingly on the rise, and many people are looking for sound information on herbal alternatives to standard antibiotics. In this indispensable reference, herbal expert Stephen Harrod Buhner explains the roots of antibiotic resistance, explores the value of herbal treatments, and provides in-depth profiles of 30 valuable herbs, noting for each one its antibiotic properties, methods for collection and preparation, dosages, potential side effects, contraindications, and alternatives. As we prepare for the end of antibiotics, this comprehensive guide is a must-have in every family's medicine cabinet.

Molecular Genetics of Bacteria, Third Edition (Snyder, Molecular Genetics of Bacteria)

Molecular Genetics of Bacteria, Third Edition (Snyder, Molecular Genetics of Bacteria)
by Larry Snyder (Author), Wendy Champness (Author)


This landmark volume provides the single most comprehensive and authoritative textbook on bacterial molecular genetics. Perfect for advanced undergraduate and graduate-level courses, the text presents the latest research on the subject in a clearly written and well-illustrated style. It provides descriptive background information, detailed experimental methods, examples of genetic analyses, and advanced material relevant to current applications of molecular genetics. While providing a deep understanding of bacterial molecular genetics, the material is integrated with biochemical, genomic, and structural information to broaden understanding. The approach centers on the most-studied bacteria, Escherichia coli and Bacillus subtilis. In addition, examples from other bacteria with medical,...

Sustainable Approaches to Controlling Plant Pathogenic Bacteria

Sustainable Approaches to Controlling Plant Pathogenic Bacteria
by V. Rajesh Kannan (Editor), Kubilay Kurtulus Bastas (Editor)


Plant diseases and changes in existing pathogens remain a constant threat to our forests, food, and fiber crops as well as landscape plants. However, many economically important pathosystems are largely unexplored and biologically relevant life stages of familiar systems remain poorly understood. In a multifaceted approach to plant pathogenic behavioral control, Sustainable Approaches to Controlling Plant Pathogenic Bacteria discusses the impact of plant pathogenic bacterial pathogenesis on scientific and economic levels. It introduces mechanisms, measuring tools, and controlling strategies you can use to meet the challenge of developing new and innovative ways to control plant diseases. The book covers many aspects of the activities of pathogenic bacteria that interact with plants. With...

Bacteria for Breakfast: Probiotics for Good Health

Bacteria for Breakfast: Probiotics for Good Health
by Kelly Dowhower Karpa (Author)


Although in Western society the beneficial aspects of bacteria have been increasingly minimized, we actually need bacteria in our digestive tracts for good health. This resource explains, to laymen and physicians, how probiotics support immune function, prevent urogenital infections, and maintain good gastrintestinal health.

Laboratory Guide for the Identification of Plant Pathogenic Bacteria

Laboratory Guide for the Identification of Plant Pathogenic Bacteria
by N. W. Schaad (Author), N. W. Schaad (Editor)


This decade has seen many advances in plant pathogenic bacteria identification, most notably polymerase chain reaction (PCR). This book features a list of available PCR primers and an appendix on Molecular Techniques. Nomenclatural changes included in this manual make identification of most plant pathogenic bacteria much easier. Many species have been given genus status and many pathovars have been returned to species rank. Each chapter in this book provides a description of the nomenclature and taxonomy being followed and a flow chart to aid in identification of plant pathogen genera is included.

To assist readers in correctly identifying bacteria, the Laboratory Guide for Identification of Plant Pathogenic Bacteria, Third Edition includes simplified methods, color photographs of...

© 2015 BrightSurf.com