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


York U invention promises rapid detection of E. coli in water
Tragedies like the E. coli outbreak in Ontario's Walkerton in May 2000 could be averted today with a new invention by researchers at York University that can detect the deadly contaminant in drinking water early.

Photosynthetic bacteria give biologists a cool new tool
Photosynthetic bacteria that have lived on Earth for 2.7 billion years are the source of a new and valuable biological regulatory tool being developed by Rice University bioengineers.

Rapid diagnostics for multidrug resistant organisms in combat-related infection
The occurrence of multidrug resistant infection is a major concern in Wounded Warriors and military Veterans, especially in combat-related injuries.

Screening method uncovers drugs that may combat deadly antibiotic-resistant bacteria
In recent years, hospitals have reported dramatic increases in the number of cases of the highly contagious, difficult-to-treat, and often deadly antibiotic-resistant bacteria carbapenem-resistant Enterobacteriaceae (CRE).

Microbial biosensor designed to evaluate water toxicity
Researchers of the Environmental Microbiology Group of the UAB Department of Genetics and Microbiology have developed a paper-based biosensor covered with bacteria to detect water toxicity.

First in-human vaccine study for malaria caused by Plasmodium vivax
Walter Reed Army Institute of Research (WRAIR) researchers recently published the results of testing a Plasmodium vivax malaria vaccine candidate in a human challenge model.

Genetically modified E. coli pump out morphine precursor
A common gut microbe could soon be offering us pain relief. Japanese bioengineers have tweaked Escherichia coli genes so that they pump out thebaine, a morphine precursor that can be modified to make painkillers.

Researchers identify most dangerous strains of often-deadly bacteria
A multi-disciplinary group of researchers at the University of Maryland School of Medicine (UM SOM) have for the first time determined the genetic makeup of various strains of E. coli, which every year kills hundreds of thousands of people around the world.

IU scientists create 'nano-reactor' for the production of hydrogen biofuel
Scientists at Indiana University have created a highly efficient biomaterial that catalyzes the formation of hydrogen -- one half of the "holy grail" of splitting H2O to make hydrogen and oxygen for fueling cheap and efficient cars that run on water.

Scientists discover that the immune system affects gut bacteria evolution
Our health is strongly dependent on the diversity of bacteria that inhabits our intestinal tract and on how the immune system tolerates it or responds to the pathogenic bacteria to prevent disease.
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...

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.

Enterohemorrhagic Escherichia coli and Other Shiga Toxin-Producing E. coli

Enterohemorrhagic Escherichia coli and Other Shiga Toxin-Producing E. coli
by Vanessa Sperandio (Editor), Carolyn Hovde Bohach (Editor)


Whether contracted through contaminated food or a trip to the local petting zoo, disease-causing E. coli is a major human health threat Most E. coli strains live harmlessly in the intestines of healthy humans and animals, but virulent strains, the enterohemorrhagic E. coli (EHEC) and certain Shiga toxin–producing E. coli (STEC), cause life-threatening infections, with young children and the elderly most at risk. Easily transmitted through contaminated water, food, and more rarely through contact between animals and people, controlling the development of EHEC and STEC outbreaks is a concern for the infectious disease community and the food industry. Covering a diverse array of topics, including microbial pathogenesis, disease pathophysiology, food safety, genetic analysis, veterinary...

Escherichia coli in Domestic Animals and Humans

Escherichia coli in Domestic Animals and Humans
by Carlton L Gyles (Author)


This book presents an authoritative and comprehensive review of disease processes and diseases caused by the bacterium Escherichia coli. It is divided into four parts: characteristics of E. coli, diseases caused by E. coli, virulence factors of E. coli, and diagnosis and prevention of diseases caused by E. coli. It represents a definitive reference work for veterinary and medical microbiologists.

Microcosm: E. Coli and the New Science of Life

Microcosm: E. Coli and the New Science of Life
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.

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)


Book by

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...

  Escherichia Coli in the Americas
by Alfredo G Torres (Editor)


Bacterial diarrheal diseases remain an important leading cause of preventable death, especially among children under five in developing countries. In the American continent, diarrheal disease and other health complications caused by Escherichia coli constitute a major public health problem, and, therefore, several research groups have dedicated their effort to understand this pathogen and provide feasible solutions to prevent, treat and reduce E. coli infections. The Latin American Coalition for Escherichia coli Research (LACER) was created as a multidisciplinary network of international research groups working with E. coli with the ultimate goal of advancing understanding of E. coli, and to prepare the next generation of American E. coli investigators. As such, this book...

E. coli: How to Stay Safe: Basics for Beginners (Health Matters Book 51)

E. coli: How to Stay Safe: Basics for Beginners (Health Matters Book 51)
by Eternal Spiral Books, http://EternalSpiralBooks.com


Escherichia coli, commonly referred to as E. col, is a food- and water-borne virus which can cause a range of symptoms and lead to severe illness or even death if not treated properly. It seems like almost every day, we hear of some new food-related outbreak or factory recall due to concerns over the safety of what we and our pets are eating.

In this guide, you will discover what E. coli is, where it comes from, and why it is dangerous. You will also learn how to treat it effectively and what to do if you or a loved one start to show other symptoms.

An ounce of prevention is worth a pound of cure. If you can’t prevent E. coli, the next best thing is to know the signs and symptoms, and dangers to watch out for, to keep you and your family safe.
++
Bacteria Transformation of  Escherichia Coli

Bacteria Transformation of Escherichia Coli


This experiment allowed me to learn how to transform the genetic makeup of bacteria, and I could apply it to other organisms. This lab was done to increase the understanding of how plasmids work. The purpose of this lab is to transform the genetic makeup of Escherichia coli using heat and Luria Broth (LB) + or – and Ampicillin so that the plasmid that contains an enzyme that makes E. coli resistant to Ampicillin will be expressed.
In order to see whether or not the bacteria has the plasmid, pGreen will be used so the bacteria will be visible under the black light, only the bacteria with the plasmid will glow because it will be the plasmid that picks up the pGreen. If there is Ampicillin with the Luria Broth, the E. coli will not grow because it is an antibiotic. If there is...

© 2016 BrightSurf.com