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
Identifying The Physiological Conditions That Promote Lateral Gene Transfer And Evolution Of New Streptococcal Pathovars
Funder
National Health and Medical Research Council
Funding Amount
$415,907.00
Summary
In the last few decades, the diseases caused by the three human pathogens, groups A, B and G streptococcus have undergone a transformation. The exchange of DNA between these species is speculated to play a role in this changing disease association. In this proposal we will identify the specific physiological and growth conditions that promote DNA transfer. Such information may help in our understanding of how new pathogenic strains of streptococci arise.
Molecular Typing And Epidemiology Of Bordetella Pertussis In Australia
Funder
National Health and Medical Research Council
Funding Amount
$552,662.00
Summary
Pertussis, commonly known as whooping cough, is an acute respiratory disease caused by Bordetella pertussis. Despite more than half a century of vaccination, pertussis has remained endemic in Australia, causing epidemic outbreaks every 3 to 4 years. Indeed the incidence has been increasing in recent years with over 11,000 cases notified in 2005.Pertussis is the commonest of all vaccine preventable diseases targeted by the Australian standard vaccination schedule. To control pertussis, appropriat ....Pertussis, commonly known as whooping cough, is an acute respiratory disease caused by Bordetella pertussis. Despite more than half a century of vaccination, pertussis has remained endemic in Australia, causing epidemic outbreaks every 3 to 4 years. Indeed the incidence has been increasing in recent years with over 11,000 cases notified in 2005.Pertussis is the commonest of all vaccine preventable diseases targeted by the Australian standard vaccination schedule. To control pertussis, appropriate epidemiological surveillance must be implemented to monitor the circulating B. pertussis strains and emergence of any new strains, in particular those that escape the protection by vaccines. This project will use a novel genomic comparison approach to find variation known as single nucleotide polymorphisms (SNP) present around the genome. We will use these SNPs to analyse a large collection of Australian and worldwide isolates to identify those SNPs most suitable for typing and determine the optimal number of SNPs needed for discrimination. A standardized, consistent and reliable typing method for strain identification will be established. We will further develop an integrated method for detecting known variation in the genes encoding the five acellular vaccine antigens. A combined method for strain identification and detection of antigenic variation will then be developed for culture-independent typing, enabling identification of the strain infecting an individual directly from a clinical sample without the need for culture. This study will establish molecular methods for surveillance of pertussis in Australia, essential for further improvement of acellular pertussis vaccines and public health control measures.Read moreRead less
Molecular Genetics And Evolution Of Antibiotic Resistant Staphylococci
Funder
National Health and Medical Research Council
Funding Amount
$432,750.00
Summary
Potentially life-threatening infections caused by Staphylococcus aureus bacteria, commonly known as Golden Staph, often arise as complications in patients within hospitals. These infections compromise the health of the patient and jeopardise their recovery from the condition for which they were initially admitted, which significantly increases healthcare costs. Golden Staph is a major cause of hospital-acquired infections in Australia and globally. The problem is largely due to the presence in h ....Potentially life-threatening infections caused by Staphylococcus aureus bacteria, commonly known as Golden Staph, often arise as complications in patients within hospitals. These infections compromise the health of the patient and jeopardise their recovery from the condition for which they were initially admitted, which significantly increases healthcare costs. Golden Staph is a major cause of hospital-acquired infections in Australia and globally. The problem is largely due to the presence in hospitals of strains that are resistant to most clinically-useful antibiotics and are therefore very difficult to eradicate; the recent isolation of strains highly-resistant to one of the last resort anti-staphylococcal antibiotics, vancomycin, is particularly worrying. The emergence of these multiresistant strains is primarily attributable to the acquisition of pre-existing resistance determinants by cell-to-cell gene transfer, a process in which plasmids, extra-chromosomal DNA elements, play a prominent role. Staphylococcal multiresistance plasmids carry genes that can confer resistance to up to 20 antimicrobial agents and are themselves capable of transfer between bacterial cells. In this project, we will define the molecular mechanisms by which staphylococcal multiresistance plasmids efficiently replicate in the host cell and are stably maintained in growing bacterial populations or when acquired by a new host after transfer; such mechanisms may well provide novel drug targets. The results will also lead to the development of improved methods for the characterisation of clinical strains and the monitoring of antibiotic resistance, and will be of broad relevance to the problem of antimicrobial resistance in bacterial pathogens. Most importantly, the application of knowledge arising from these studies to the design and implementation of rational antibiotic usage policies has the potential to extend the efficacy of existing and future anti-staphylococcal therapies.Read moreRead less
Some of the world's most important diseases, including important diseases of indigenous chilren and the hospitalised elderly are caused by bacteria that carry a surface coating called a capsule. It is not clear how this capsule is retained by bacteria. Resolution of this question could lead to the development of new disinfectants that will stop hospital-acquired infections, to new reagents that can be incoporated into medical devices where bacteria frequently grow, and new antibiotics.