Science Current Events | Science News | Brightsurf.com
 

Bacterial fibers critical to human and avian infection

February 06, 2014
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.

In a new study conducted in Assistant Professor Melha Mellata's lab, at the Biodesign Institute at Arizona State University, lead author Alyssa K. Stacy and her colleagues examine one such bacterial adversary, Avian pathogenic Escherichia coli (APEC).

The research, conducted in collaboration with scientists at the University of Florida, Gainesville, appears in the current issue of the journal PLOS ONE.

The researchers targeted a specific group of threadlike fibers known as E. coli common pilus (ECP), which adorn bacterial cell surfaces. In the first study of its kind, they analyzed the way these structures contribute to APEC's ability to cause infection and form dense cell aggregates known as biofilms.

APEC infections are a serious threat to poultry, causing both systemic and localized infections, collectively known as colibacillosis. These afflictions cause significant economic losses to the poultry industry, due to the costs of treatment for infected birds, lowered rates of egg production, and mortality.

Further, APEC infections may pose a risk to humans, due to their zoonotic potential-their ability to infect human hosts. A better understanding of infectious capacity (or virulence) and zoonotic potential are therefore essential for combatting these hazardous pathogens.

Stacy was an undergraduate student in Dr. Mellata's lab, and was partialy supported by funding from School of Life Sciences Undergraduate Research (SOLUR), ASU. She was joined by Biodesign researchers Natalie M. Mitchell, Jacob T. Maddux, and Roy Curtiss III (who directs the Institute's Center for Infectious Diseases and Vaccinology).

Avian Pathogenic E. coli (APEC) belong to a broad group of extraintestinal pathogenic E. coli (ExPEC) strains. Colibacillosis, caused by APEC in birds, leads to serious illness, often attacking the avian respiratory system, producing systemic or localized infections depending on the age and gender of bird, immunologic health and various environmental factors.

Because APEC and human ExPEC forms share important virulence characteristics, possible zoonotic transmission is a serious health concern. APEC may also provide a reservoir for virulence genes that may be acquired by human strains.

Many types of bacteria produce extracellular surface fibers like ECP, enabling them to adhere to one another as well as to various surfaces. But such fibers or pili perform other vital functions, particularly in the case of pathogenic bacteria. Pili, including those projecting from the surfaces of E. coli, are capable of recognizing specific host cell receptors during their initial phase of colonization.

Bacteria make further use of their pili to form cellular biofilms. Such bacterial aggregates are of clinical importance, as they provide reservoirs for pathogenic organisms to persist in the host and often display increased resistance to antibiotics.

E. coli common pilus (ECP) was originally identified in an ExPEC form known to cause neonatal meningitis in humans, but was later recognized as a component in all classes of E. coli-both pathogenic and benign.

While E. coli bacteria exist primarily as beneficial residents of the human intestine, extraintestinal variants are responsible for diarrheal diseases like hemorrhagic colitis, as well as urinary tract infections, neonatal meningitis, sepsis, and pneumonia. The toll of such diseases-particularly in the developing world-is substantial, claiming some 2.5 million lives per year. Most of these victims are children.

The current study draws on examinations of ECP both in vitro and in vivo. The aim was to determine the prevalence of ECP among APEC strains and evaluate its contribution in the early stage of biofilm formation and host cell recognition. Additionally, the study assessed ECP's role in virulence in baby chicks.

The new research demonstrates-for the first time-the prevalence of ecpA, a gene coding for a major structural subunit of ECP in a majority APEC sequences examined. (The complex architecture of ECP fibers is composed of 6 distinct structural subunits.) With the aid of PCR methods, the group tested 167 APEC strains derived from chickens and turkeys afflicted with colibacillosis, 76 percent of which tested positive for ecpA, which was previousely associated with human pathogenic E. coli.

The authors stress that the results confirm that APEC and human pathogenic E. coli strains share virulence traits. They further speculate that ecpA may permit the persistence of E. coli bacteria in the intestine, where they exist in a non-threatening state, before migrating to alternate, extraintestinal sites, becoming pathogenic.

Environmental conditions, including low pH, low growth temperature and high acetate concentration have been shown to upregulate the expression of ECP in human E. coli strains that cause urinary tract infections, meningitis, and diarrheal diseases. In the current study, an APEC strain was found to adhere to human cervical cells in a manner similar to human ExPEC infections. Further, the results showed that adorning APEC with anti-ECP antibodies- a process known as opsonization-could significantly inhibit bacterial adherence. This finding suggests that ECP could be considered as a potential antigen for vaccines for both human and poultry infections.

The formation of biofilms is a common bacterial property, including in E. coli, where the adaptation increases survivability inside and outside of the host and provides an ideal environment for the exchange of genetic material. Bacteria forming biofilms frequently display antibiotic resistance and can be tenacious foes to combat medically. Deletion of ECP-related genes was shown to reduce biofilm production.

Finally, the study attempted to evaluate APEC virulence in baby chicks, using strains with deleted ECP genes. Results show a reduction in virulence. In fact, the potential for colonization among the ECP deletion strains was reduced, particularly in the bloodstream.

The new work demonstrates multiple roles for ECP in APEC, and thus presents a plausible target for future therapeutics aimed at these serious infections of both humans and animals.

"Our study has clearly shown that although the gene of ECP was found in a large number of APEC, these bacteria express this gene differently when they are in contact with cells or in biofilm," Mellata says. "Elucidating how the expression of some genes is turned on or off by different factors will help us understand how these bacteria cause disease."

Arizona State University


Related Escherichia Coli Current Events and Escherichia Coli News Articles


New research shows how pathogenic E. coli O157:H7 binds to fresh vegetables
Food-poisoning outbreaks linked to disease-causing strains of the bacterium Escherichia coli are normally associated with tainted meat products.

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.

A way to end recurrent urinary tract infections? Study with mice gives hope
Millions of people worldwide - mostly women - suffer from recurrent urinary tract infections (UTIs) that seriously degrade their health and quality of life. Antibiotics treat individual infections, but preventing recurrent ones largely has been unattainable because of the way bacteria lodge in the inner layers of the bladder and quietly hide from drugs that can kill them.

Big data tackles tiny molecular machines
Open, feed, cut. Such is the humdrum life of a motor molecule, the subject of new research at Rice University, that eats and excretes damaged proteins and turns them into harmless peptides for disposal.

In the lab, scientists coax E. coli to resist radiation damage
Capitalizing on the ability of an organism to evolve in response to punishment from a hostile environment, scientists have coaxed the model bacterium Escherichia coli to dramatically resist ionizing radiation and, in the process, reveal the genetic mechanisms that make the feat possible.

Fighting for survival in the gut: Unravelling the hidden variation of bacteria
Our intestines harbour an astronomical number of bacteria, around 100 times the number of cells in our body, known as the gut microbiota.

Beneficial anti-inflammatory effects observed when plant extracts fed to sick pigs
Porcine reproductive and respiratory syndrome (PRRS) is the most expensive and invasive disease for pig producers on a global scale. Though it is not occurring on every farm, it is the biggest disease problem in the pig industry, said a University of Illinois animal sciences researcher.

Harvested rainwater harbors pathogens
South Africa has been financing domestic rainwater harvesting tanks in informal low-income settlements and rural areas in five of that nation's nine provinces.

Researchers tune in to protein pairs
Rice University scientists have created a way to interpret interactions among pairs of task-oriented proteins that relay signals. The goal is to learn how the proteins avoid crosstalk and whether they can be tuned for better performance.

Synthetic genetic clock checks the thermometer
Genetic systems run like clockwork, attuned to temperature, time of day and many other factors as they regulate living organisms.
More Escherichia Coli Current Events and Escherichia Coli News Articles

Escherichia coli, Second Edition: Pathotypes and Principles of Pathogenesis

Escherichia coli, Second Edition: Pathotypes and Principles of Pathogenesis
by Michael Donnenberg (Editor)


The 2e of Escherichia coli is a unique, comprehensive analysis of the biology and molecular mechanisms that enable this ubiquitous organism to thrive. Leading investigators in the field discuss the molecular basis of E. coli pathogenesis followed by chapters on genomics and evolution. Detailed descriptions of distinct strains reveal the molecular pathogenesis of each and the causes of intestinal and extra-intestinal infections in humans. This work concludes with a presentation of virulence factors common to two or more pathotypes. The book is a great resource for references and up-to-date knowledge for anyone who studies E. coli pathogenesis, either as established investigators or investigators new to the field. It is also an excellent text for those who teach mechanisms of pathogenesis...

Microcosm: E. Coli and the New Science of Life (Vintage)

Microcosm: E. Coli and the New Science of Life (Vintage)
by Carl Zimmer (Author)


A Best Book of the YearSeed Magazine • Granta Magazine • The Plain-DealerIn this fascinating and utterly engaging book, Carl Zimmer traces E. coli's pivotal role in the history of biology, from the discovery of DNA to the latest advances in biotechnology. He reveals the many surprising and alarming parallels between E. coli's life and our own. And he describes how E. coli changes in real time, revealing billions of years of history encoded within its genome. E. coli is also the most engineered species on Earth, and as scientists retool this microbe to produce life-saving drugs and clean fuel, they are discovering just how far the definition of life can be stretched.

Pathogenic Escherichia coli: Molecular and Cellular Microbiology

Pathogenic Escherichia coli: Molecular and Cellular Microbiology
by Stefano Morabito (Editor)


In recent years, a great deal of knowledge has accumulated on the features associated with the virulence of pathogenic E. coli. A large number of virulence genes have been identified and their products characterized. Great strides have been made in the understanding of the pathogenic mechanisms and the bacterium-host interaction. However, much remains elusive in the understanding of pathogenicity at a cellular and sub-cellular level. This is largely due to E. coli genome's plasticity: it generates great variability and facilitates the rapid emergence of new pathogenic variants. Elucidating the mechanisms underlying the evolution of these pathogens and their interactions with the host are key stages for disease prevention. This book reviews the most important recent findings of the studies...

Escherichia coli and Salmonella: Cellular and Molecular Biology (2 Volumes)

Escherichia coli and Salmonella: Cellular and Molecular Biology (2 Volumes)
by Frederick C. Neidhardt (Editor)


This is the long-awaited second edition of an invaluable classic! Escherichia coli occupies a central role in contemporary molecular biology. It is the unicellular organism about which most is known - all molecular and cellular biologists will want a copy of this book. In 154 chapters, 250 expert authors and editors present the state of the art. Completely rewritten and restructured, the second edition offers a whole new approach to the subject.

Escherichia Coli Infections (Deadly Diseases and Epidemics)

Escherichia Coli Infections (Deadly Diseases and Epidemics)
by Shannon D. Manning (Author), Hilary, M.D. Babcock (Editor), David Heymann (Editor)


Escherichia Coli Infections (Deadly Diseases and Epidemics)

Escherichia coli infections

Escherichia coli infections
by Viroj Wiwanitkit (Author)


The “E. coli” may be a new vocabulary that many people would be unfamiliar to them. This word is the name of the disease that is a major problem and concern in global health that still presents as outbreaks in many countries, especially those in Europe. E. coli infection is a bacterial disease caused by a pathogenic bacterium namely Escherichia coli.

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.

Poisoned: The True Story of the Deadly E. Coli Outbreak That Changed the Way Americans Eat

Poisoned: The True Story of the Deadly E. Coli Outbreak That Changed the Way Americans Eat
by Jeff Benedict (Author)


"Your perfect beach book has arrived. With Poisoned, Jeff Benedict manages to deliver the full literary experience of a medico-legal thriller in a work of nonfiction that, fortuitously enough, could not be more relevant to recent headlines."—The New York TimesIn this riveting work of narrative nonfiction, award-winning journalist and best-selling author Jeff Benedict chronicles the events surrounding the biggest food-poisoning epidemic in US history and how this unprecedented crisis sparked public awareness about unsanitary practices in the fast food industry. Poisoned draws on access to confidential documents and exclusive interviews with the real-life characters at the center of the drama.Jeff Benedict is considered one of America's top nonfiction writers. He is the author of nine...

Missing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern Plagues

Missing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern Plagues
by Martin J. Blaser (Author)


A critically important and startling look at the harmful effects of overusing antibiotics, from the field's leading expert Tracing one scientist’s journey toward understanding the crucial importance of the microbiome, this revolutionary book will take readers to the forefront of trail-blazing research while revealing the damage that overuse of antibiotics is doing to our health: contributing to the rise of obesity, asthma, diabetes, and certain forms of cancer. In Missing Microbes, Dr. Martin Blaser invites us into the wilds of the human microbiome where for hundreds of thousands of years bacterial and human cells have existed in a peaceful symbiosis that is responsible for the health and equilibrium of our body. Now, this invisible eden is being irrevocably damaged by some of our most...

Escherichia Coli and Salmonella Typhimurium: Vols 1-2: Cellular and Molecular Biology

Escherichia Coli and Salmonella Typhimurium: Vols 1-2: Cellular and Molecular Biology
by Frederick C. Neidhardt (Editor), etc. (Editor), et al (Editor)




© 2014 BrightSurf.com