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


Antibiotic resistance enzyme caught in the act
Resistance to an entire class of antibiotics - aminoglycosides -- has the potential to spread to many types of bacteria, according to new biochemistry research.

Bacterial Gut Biome May Guide Colon Cancer Progression
Colorectal cancer develops in what is probably the most complex environment in the human body, a place where human cells cohabitate with a colony of approximately 10 trillion bacteria, most of which are unknown.

Fighting antibiotic resistance with 'molecular drill bits'
n response to drug-resistant "superbugs" that send millions of people to hospitals around the world, scientists are building tiny, "molecular drill bits" that kill bacteria by bursting through their protective cell walls.

New clues found to preventing lung transplant rejection
Organ transplant patients routinely receive drugs that stop their immune systems from attacking newly implanted hearts, livers, kidneys or lungs, which the body sees as foreign.

MD Anderson researcher uncovers some of the ancient mysteries of leprosy
Research at The University of Texas MD Anderson Cancer Center is finally unearthing some of the ancient mysteries behind leprosy, also known as Hansen's disease, which has plagued mankind throughout history.

Beauty & Bacteria: Slim, Attractive Men Have Less Nasal Bacteria than Heavy Men
Do attractive traits tell us anything about a person's reproductive health? New research in the American Journal of Human Biology reveals a link between Body Mass Index (BMI) and the amount of bacteria colonizing noses.

How bacteria communicate with us to build a special relationship
Communication is vital to any successful relationship. Researchers from the Institute of Food Research and the University of East Anglia have discovered how the beneficial bacteria in our guts communicate with our own cells.

Bacterial fibers critical to human and avian infection
Escherichia coli-a friendly and ubiquitous bacterial resident in the guts of humans and other animals-may occasionally colonize regions outside the intestines. There, it can have serious consequences for health, some of them, lethal.

VIB scientists find new strategy to combat bacterial infections
Increasing numbers of bacteria are developing antibiotic resistance. This forms a significant challenge in the battle against bacterial infections.

Tuberculosis: Nature has a double-duty antibiotic up her sleeve
Technology has made it possible to synthesize increasingly targeted drugs. But scientists still have much to learn from Mother Nature.
More Pathogenic Bacteria Current Events and Pathogenic Bacteria News Articles

Pathogenic bacteria and microbial-source tracking markers in Brandywine Creek Basin, Pennsylvania and Delaware, 2009-10: USGS Scientific Investigations Report 2011-5164

Pathogenic bacteria and microbial-source tracking markers in Brandywine Creek Basin, Pennsylvania and Delaware, 2009-10: USGS Scientific Investigations Report 2011-5164
by Joseph W. Duris (Author), Andrew G. Reif (Author), et al. (Creator)


The City of Wilmington, Delaware, is in the downstream part of the Brandywine Creek Basin, on the main stem of Brandywine Creek. Wilmington uses this stream, which drains a mixed-land-use area upstream, for its main drinking-water supply. Because the stream is used for drinking water, Wilmington is in need of information about the occurrence and distribution of specific fecally derived pathogenic bacteria (disease-causing bacteria) and their relations to commonly measured fecal-indicator bacteria (FIB), as well as information regarding the potential sources of the fecal pollution and pathogens in the basin. This study focused on five routinely sampled sites within the basin, one each on the West Branch and the East Branch of Brandywine Creek and at three on the main stem below the...

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




Pathogenic and Clinical Microbiology: A Laboratory Manual (Books)

Pathogenic and Clinical Microbiology: A Laboratory Manual (Books)
by Sharon S. Rowland (Author), Walsh (Author), Carnahan (Author)


A straightforward, clinically focused laboratory manual. Will be an accompaniment to any microbiology textbook. It allows the student to work through the most common laboratory exercises while also testing their learning curve by identifying a micro-organism through testing procedures. easy to read - presented in a clearly written, succinct style with simple tables to work through; logical approach - moves the student through 20 pathogenic microbiology exercises, including 4 "unknowns", the student is then led through 11 clinical microbiology exercises

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...

Identification of Unusual Pathogenic Gram-Negative Aerobic and Facultatively Anaerobic Bacteria

Identification of Unusual Pathogenic Gram-Negative Aerobic and Facultatively Anaerobic Bacteria
by Robin S. Weyant (Author), Robin S. Weyant (Editor)


The second edition of this text includes chapters on recent nomenclature changes; presumptive identification key; names of fatty acids found in bacteria; bacterial identificaiton using King's key; and bacterial identification by cellular fatty acid analysis.

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.

Injured Index and Pathogenic Bacteria: Occurence and Detection in Foods, Water and Feeds

Injured Index and Pathogenic Bacteria: Occurence and Detection in Foods, Water and Feeds
by Bibek Ray (Author)


This book emphasizes the occurrence of sublethal injury in the indicator and pathogenic bacteria commonly encountered in foods, water and feed and modifications of the currently recommended methods for the effective detection of these bacteria. Chapters include methods for recovering injured "classical" enteric pathogenic bacteria from foods and for recovering injured pathogenic organisms from animal food. Detection and significance of injured indicator and pathogenic bacteria in water are explained, as well as detection of injured sporeforming bacteria from foods. This volume is extremely useful for individuals in the academic institutions, industries, federal and state regulatory agencies, public health service and hospitals who are interested in effective detection of indicator and...

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 bacteriaWhen 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 what you need to...

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...

© 2014 BrightSurf.com