Examination Of The Role Of Biofilms In Infection With Enteropathogenic Escherichia Coli
Funder
National Health and Medical Research Council
Funding Amount
$456,382.00
Summary
Many infections are caused by bacteria living in communities, known as biofilms. Enteropathogenic E. coli (EPEC) is a major cause of diarrhoea and results in the death of millions of children annually. We have found a link between biofilm formation by EPEC and disease. In this project we will examine how biofilm formation by EPEC occurs and the contribution of biofilm formation to disease. The results of this study may indicate new ways to treat and prevent E. coli diarrhoea.
Dissemination And Virulence Properties Of The She Pathogenicity Island Of Shigella Flexneri.
Funder
National Health and Medical Research Council
Funding Amount
$110,625.00
Summary
Bacterial species belonging to the genus Shigella are responsible for intestinal diseases ranging from mild diarrhoea to life threatening bacillary dysentery. Such diseases kill over a million people, mainly infants in developing countries, every year and lead to serious morbidity and mortality even in industrialised countries with well developed health care systems. In many cases the virulence of Shigella species is augmented by large fragments of DNA, called pathogenicity islands, that carry g ....Bacterial species belonging to the genus Shigella are responsible for intestinal diseases ranging from mild diarrhoea to life threatening bacillary dysentery. Such diseases kill over a million people, mainly infants in developing countries, every year and lead to serious morbidity and mortality even in industrialised countries with well developed health care systems. In many cases the virulence of Shigella species is augmented by large fragments of DNA, called pathogenicity islands, that carry genes which contribute to the development of disease (pathogenesis) in humans. Pathogenicity islands are important genetic elements which appear to spread independantly throughout bacterial populations and therefore contribute to the emergence of new virulence traits in bacteria. Recently, we identified two related pathogenicity islands carried by both Shigella flexneri and other species of the genus Shigella. The two pathogenicity islands belong to a unique class of genetic elements found in Shigella species and virulent strains of the intestinal bacterium E. coli. Our current study is aimed at (1) understanding the mechanisms by which one of these islands, the she pathogenicity island, spreads from one bacterial strain to another to introduce disease-producing or virulence genes to new bacteria and (2) to study how the sigA virulence gene, carried on the she pathogenicity island, contributes to disease development in humans. We know that sigA encodes a protein toxin which contributes to the loss of fluid from the intestines of rabbits that have been experimentally infected with Shigella flexneri. We propose to study the structure and function of the SigA protein to determine how it interacts with tissues to produce a pathological state. Such studies will enhance our understanding of the process of disease development and contribute to the investigation and assessment of new strategies for therapeutic intervention.Read moreRead less
Contribution Of Shigella And Escherichia Coli Pathogenicity Islands To Diarrhoeal Disease
Funder
National Health and Medical Research Council
Funding Amount
$303,677.00
Summary
Diarrhoea resulting from infection with Shigella and Escherichia coli is a major cause of sickness and death in the developing world, especially in children. Even in Australia, these bacteria, which may be food borne, are occasionally responsible for life threatening infections. In this study, we will investigate the contribution to diarrhoeal disease of large fragments of foreign DNA which have been recently acquired by these bacteria. We will characterise several of these elements in detail, i ....Diarrhoea resulting from infection with Shigella and Escherichia coli is a major cause of sickness and death in the developing world, especially in children. Even in Australia, these bacteria, which may be food borne, are occasionally responsible for life threatening infections. In this study, we will investigate the contribution to diarrhoeal disease of large fragments of foreign DNA which have been recently acquired by these bacteria. We will characterise several of these elements in detail, identifying novel virulence determinants and toxins in the process. We will also explore the means by which these packages of nasty DNA transfer between bacteria and investigate their potential to give rise to new, more virulent strains of bacteria. This study is particularly significant because it will lead to an improved understanding of how bacteria cause disease and may help to guide us in developing better strategies for the prevention of bacterial diarrhoea. Specifically, the work done on characterising large clusters of virulence genes will allow us to construct safer bacterial vaccines and we expect that in the future this knowledge will contribute to the development of new and better diagnostic and therapeutic agents against these harmful bacteria.Read moreRead less
Role Of Novel Mobile Elements In The Infiltration Of Antibiotic Resistance Genes Into Clinical Isolates.
Funder
National Health and Medical Research Council
Funding Amount
$421,650.00
Summary
Bacteria have a remarkable ability to capture and spread antibiotic resistance genes. This phenomenon is a particular problem in our hospitals and in the community as multi-drug resistant pathogenic organisms have been selected over time as a result of the use of antibitoics. Moreover the incidence of resistance appears to be on the increase. Once resistant strains appear they can greatly complicate the treatment of infections and the eradication of such pathogens from a hospital is both difficu ....Bacteria have a remarkable ability to capture and spread antibiotic resistance genes. This phenomenon is a particular problem in our hospitals and in the community as multi-drug resistant pathogenic organisms have been selected over time as a result of the use of antibitoics. Moreover the incidence of resistance appears to be on the increase. Once resistant strains appear they can greatly complicate the treatment of infections and the eradication of such pathogens from a hospital is both difficult and costly. We have been working on the problem of how antibiotic resistance genes are spread for a number of years and have identified a novel genetic element that can capture resistance genes by a process of site-specific recombination. This element, the integron, is common in mutli-drug resistant clinical isolates. To be captured by an integron, an antibiotic resistance gene has to be part of a mobile element known as a gene cassette. Although the application of antibiotics acts to amplify pathogens that are resistant and favours their persistance in hospitals, it is generally recognized that neither the gene cassette nor the drug resistance gene evolve in the hospital. Rather, these genes make their way into human pathogens from bacteria that normally reside in other environments, for example soil or water. In this project, we will investigate one route by which drug resistance genes and integrons might find their way into clinically relevant strains and what the sources of the resistance genes and gene cassettes might be. A greater understanding of these processes will help in developing strategies to limit the spread of drug resistant bacteria into and around hospitals.Read moreRead less
Characterisation Of A Novel Type Of Promoter Controlling Expression Of Virulence Genes In Neisseria.
Funder
National Health and Medical Research Council
Funding Amount
$200,880.00
Summary
This project will investigate how two different types of bacteria control genes that are involved in determining their disease-causing ability. The expression of many bacterial genes is controlled by a sophisticated battery of regulatory systems that respond to individual, very specific, environmental signals. Such regulatory systems are capable of exerting very precise control over the level of gene expression, in response to the concentration of specific molecules in the immediate environment. ....This project will investigate how two different types of bacteria control genes that are involved in determining their disease-causing ability. The expression of many bacterial genes is controlled by a sophisticated battery of regulatory systems that respond to individual, very specific, environmental signals. Such regulatory systems are capable of exerting very precise control over the level of gene expression, in response to the concentration of specific molecules in the immediate environment. However, there is evidence to suggest that many important disease-causing bacteria are much less reliant on specific regulatory systems. Instead, these bacteria rely more heavily what have been termed global systems for the regulation of gene expression. Such systems typically respond to less specific signals, such as the growth rate of the bacterial cell, but nevertheless appear capable of very precise control. We have evidence for a previously uncharacterised type of global control system that appears to be widespread amongst bacteria. It is likely that many virulence genes in a variety of disease-causing bacteria will prove to be controlled by similar means. Therefore this project will not only provide an insight into how expression of these particular virulence determinants is regulated, but will yield data that may help in our understanding of precise global regulatory processes in other bacterial species of medical importance.Read moreRead less
Molecular Typing Of Salmonella Enterica Serovar Typhimurium
Funder
National Health and Medical Research Council
Funding Amount
$272,545.00
Summary
Salmonella mainly causes food poisoning and is a significant human health problem. Different Samonella forms are identified by serotyping and many serovars have been given a name . There are more than 2000 serovars. The best known serovar is Typhimurium which is the cause of 40% of salmonella infections. Typhimurium is so frequently involved in infections it is necessary to further divide it for outbreak investigations and long term monitoring of the organism. The only widely used method to subd ....Salmonella mainly causes food poisoning and is a significant human health problem. Different Samonella forms are identified by serotyping and many serovars have been given a name . There are more than 2000 serovars. The best known serovar is Typhimurium which is the cause of 40% of salmonella infections. Typhimurium is so frequently involved in infections it is necessary to further divide it for outbreak investigations and long term monitoring of the organism. The only widely used method to subdivide Typhimurium is phage typing, which is done only in major laboratories (2 in Australia). Phage typing is based on lysis patterns of a test isolate to a set of 34 phages. Phage typing has played a crucial role in tracking the organism, for example the emergence of a multidrug resistance new type (DT204c) in UK and US. The technique is simple but the problem is that reactions vary with slight change in conditions and scoring the reaction results is very subjective. We propose to replace the typing system with one based on the DNA method PCR, so it will be simple, fast and accurate. We will use a DNA fingerprinting technique called AFLP (amplified fragment length polymorphism) to find markers (DNA segments) that are specific to phage types and design PCR assays based on the markers we find. Such a typing system will retain the essence of phage typing by providing continuity of the valuable epidemiological database on phage types. Further the typing system could easily be expanded to accommodate any new types by finding more markers while the current phage typing system is very difficult to expand (last done in 1977 and is behind in our needs). This project will establish a general approach for designing typing systems based on molecular biology for other pathogens and could have a major impact on the surveillance of bacterial infections in the 21st century.Read moreRead less
Some bacteria can cause inflammation of the brain (bacterial meningitis). This leads to 170,000 deaths annually in the world. Many patients who survive after antibiotic treatment have lifelong disabilities like deafness, and problems of memory and learning. We aim to show that a certain biochemical pathway in the brain contributes to death and disability, with a view to identifying new drug treatments that can be used alongside antibiotics to improve disease outcomes.
Global Regulation Of Toxin Production In Clostridium Perfringens
Funder
National Health and Medical Research Council
Funding Amount
$389,860.00
Summary
This project involves an investigation of how the bacteria that cause an often fatal wound infection control the production of the toxic proteins that are essential elements of the disease process. In all pathogenic bacteria there are specific genes that encode the virulence factors that are involved in the disease. The expression of these genes is generally controlled by the products of other genes known as regulatory genes. The function of these regulatory networks is generally responsive to e ....This project involves an investigation of how the bacteria that cause an often fatal wound infection control the production of the toxic proteins that are essential elements of the disease process. In all pathogenic bacteria there are specific genes that encode the virulence factors that are involved in the disease. The expression of these genes is generally controlled by the products of other genes known as regulatory genes. The function of these regulatory networks is generally responsive to environmental stimuli. This project involves the detailed functional analysis of a regulatory network that was first identified in this laboratory and which controls the expression of extracellular toxins that have been implicated in gas gangrene. The overall objectives of the project are to develop a detailed understanding of the mechanisms involved in this regulatory process. Specifically, the project aims to determine the functional components of the regulatory proteins that interact with the environmental signal or which bind to the genes encoding the bacterial toxins, to determine the nature of the target sites to which the regulatory proteins bind, and to examine the hypothesis that there is another regulatory gene that is involved in this process. The project will make a major contribution to our knowledge of the complex interactions that occur between an invading bacterium and the host tissues. If we are to fully comprehend how bacteria cause disease then it is critical that we understand how bacteria control the production of the toxic products that are an integral part of the disease process.Read moreRead less
Origins And Relationships Of Shigella And Enteroinvasive Escherichia Coli
Funder
National Health and Medical Research Council
Funding Amount
$377,310.00
Summary
Shigella is a well known highly infectious human pathogen with as few as 10 cells allowing effective spread by infected food or water, and also by person to person contact. Shigellosis is a particularly significant disease for children due to lack of pre-existing immunity and greater chance of transfer by fecal-oral route. One group of E. coli called Enteroinvasive E. coli (EIEC) resembles Shigella in many aspects from disease symptoms to biochemical properties. EIEC is a major cause of diarrhoe ....Shigella is a well known highly infectious human pathogen with as few as 10 cells allowing effective spread by infected food or water, and also by person to person contact. Shigellosis is a particularly significant disease for children due to lack of pre-existing immunity and greater chance of transfer by fecal-oral route. One group of E. coli called Enteroinvasive E. coli (EIEC) resembles Shigella in many aspects from disease symptoms to biochemical properties. EIEC is a major cause of diarrhoea in less developed countries and has also caused large outbreaks in developed countries. It is now clear that Shigella and E. coli are really one species. EIEC and Shigella strains are variants of E. coli with humans as the only host. However separation of the two in all records and most studies means that there is no integrated understanding of the forms. We aim to study the relationships of Shigella and EIEC and expect significant insights into the origins of Shigella-EIEC. This will facilitate diagnosis and understanding of the disease(s) and lead to a far better classification . EIEC-Shigella strains have arisen from other E. coli independently. This has happened seven times in the derivation of Shigella and we expect more such events with EIEC. An interesting phenomenon during this process is that strains tend to lose metabolic functions. In this study we will look at what, why and how functions are lost. O antigens are important in evading the host immune system. Shigella strains obtained many O antigens, the majority apparently from other species. This is quite likely the key to its success. We will look at how Shigella obtained new O antigens. This project will be significant in the understanding of Shigell-EIEC, a very significant human pathogen, and in general for understanding emergence of new pathogens.Read moreRead less
COMPARATIVE ANTI-BACTERIAL IMMUNITY IN THE URINARY TRACT: DOES ONE SIZE FIT ALL?
Funder
National Health and Medical Research Council
Funding Amount
$376,781.00
Summary
Urinary tract infections (UTI), which start as a bladder infection and often evolve to encompass the kidneys, are among the most common infectious diseases of humans. It is estimated that 40 to 50% of adult healthy women have experienced at least one UTI episode in their lifetime. Bacteria cause most UTI and this study will focus on how these bacteria survive in the urinary tract and will provide key insight into the ways in which human immune responses develop to counteract these bacteria.