Modelling Streptococcal Urogenital Tract Infection To Study Mechanisms Of Bacterial Colonization And Persistence
Funder
National Health and Medical Research Council
Funding Amount
$412,085.00
Summary
Colonization of the urogenital tract with bacterial pathogens is one of the most common infections in humans. In Australia millions of people are colonized in their urogenital tracts at any given time, often asymptomatically, and many such individuals require medical intervention for the treatment of consequent infections that result from persistent colonization. Bacterial colonization of the urogenital tract is associated with a variety of disease presentations including urinary tract infection ....Colonization of the urogenital tract with bacterial pathogens is one of the most common infections in humans. In Australia millions of people are colonized in their urogenital tracts at any given time, often asymptomatically, and many such individuals require medical intervention for the treatment of consequent infections that result from persistent colonization. Bacterial colonization of the urogenital tract is associated with a variety of disease presentations including urinary tract infections and neonatal infections resulting from vertical transmission of colonizing bacteria from mothers to newborns. Aside from sexually-transmitted diseases the most prominent bacterial pathogens that colonize the urogenital tract are Group B Streptococcus (GBS) and Escherichia coli. GBS in particular exist in the female urogenital tract as a persistent microbial reservoir in up to 40% of pregnant women and are transmitted to newborns in up to 72% of live births. Colonization of newborns leads to invasive disease including pneumonia, sepsis, and meningitis. While the disease presentations resulting from colonization of the urogenital tract vary the underlying basis that leads to disease is antecedent bacterial persistence in the urogenital tract despite immune system activation. The mechanisms whereby GBS evade immune responses in the urogenital tract to allow their survival are unknown. I will define the immune-evasion mechanisms and virulence traits used by GBS, as a model urogenital pathogen, to successfully colonize the urogenital tract in the face of mounting immune responses. These studies will provide a better understanding of the pathogenesis of urogenital disease in terms of bacterial colonization and immune-evasion strategies. This will shed light onto new approaches for the prevention and treatment of urogenital disease in humans such as improved vaccination, locally acting cytokines, and deliberate colonization with non-invasive strains for the prevention of disease.Read moreRead less
Understanding The Complex Relationship Between Host, Pathogen And Antibiotic Factors On Treatment Outcome In Serious Bacterial Infections
Funder
National Health and Medical Research Council
Funding Amount
$380,945.00
Summary
Millions of people still die every year from bacterial infections despite the availability of antibiotics. The same bacterial infection in one person can behave very differently in another person, so infections can range from trivial to life-threatening or fatal. Understanding the relationship between the patient, the infecting bacteria and the antibiotic treatment given will ultimately help to predict and improve outcomes for patients with serious bacterial infections.
Beta-lactamase Mediated Antibiotic Resistance In Gram-negative Pathogens: How Does Genotype Relate To Phenotype?
Funder
National Health and Medical Research Council
Funding Amount
$397,869.00
Summary
Unfortunately, one of the consequences of antibiotic usage (and in particular over-use and mis-use) is the development of resistance; if a small proportion of bacteria survive treatment, they can grow and replace the previous population of sensitive bacteria. In addition, the genes that confer resistance can be transferred between different bacterial lineages, thus facilitating the dissemination of resistant bacteria. The most important mechanism of penicillin resistance is through the expressio ....Unfortunately, one of the consequences of antibiotic usage (and in particular over-use and mis-use) is the development of resistance; if a small proportion of bacteria survive treatment, they can grow and replace the previous population of sensitive bacteria. In addition, the genes that confer resistance can be transferred between different bacterial lineages, thus facilitating the dissemination of resistant bacteria. The most important mechanism of penicillin resistance is through the expression of an enzyme called a beta-lactamase. This enzyme breaks down the penicillin. Beta-lactamase enzymes come in many different varieties, and new varieties appear quite frequently. Remarkably, when new kinds of penicillin are invented to circumvent resistance, the appearance of new beta-lactamases that can break down these new penicillins follows shortly thereafter. The objectives of our research are twofold. Firstly, it is now clear that the relationship between the beta-lactamase genes in a bacterium and the resulting pattern of resistance can be very complex. It can involve both the broad nature of the genes, the numbers of duplicates of the genes inside the cell, and very minor changes to the gene sequences. We will probe the relationship between the gene and resistance so as to understand it at a deeper level. Secondly, we will use this information to develop very efficient and cost affective methods for keeping track of the spread of the different varieties of beta-lactamase genes. These methods will be designed to be carried out on real-time PCR machines. These high-tech devices are general purpose gene analyzers that can carry out many different kinds of genetic assay. They are rapidly becoming ubiquitous in clinical microbiology laboratories. The use of these methods will provide much hard information that will be used to minimise the dissemination of antibiotic resistance.Read moreRead less
Functional Biology Of Large Serine Recombinases From Mobile Antibiotic Resistance Elements
Funder
National Health and Medical Research Council
Funding Amount
$436,328.00
Summary
In recent years there has been increasing concern about the emergence of multiply antibiotic resistant strains of many common bacterial pathogens. The development of multiple resistance phenotypes has already led to compromises in the ability to successfully treat infected patients and to increased treatment costs. The emergence of these resistant bacteria is the result of excessive or inappropriate use of antibiotics and the ability of antibiotic resistance genes to be transferred from resistan ....In recent years there has been increasing concern about the emergence of multiply antibiotic resistant strains of many common bacterial pathogens. The development of multiple resistance phenotypes has already led to compromises in the ability to successfully treat infected patients and to increased treatment costs. The emergence of these resistant bacteria is the result of excessive or inappropriate use of antibiotics and the ability of antibiotic resistance genes to be transferred from resistant to susceptible bacteria, either within or between bacterial species. The movement of resistance elements that are integrated into the bacterial genome often involves their excision from their existing site and their subsequent integration into another site in the same or a different genome. This project centres on the analysis of this process in resistant bacteria that cause major disease problems in our hospitals. The research project will focus on MRSA (Multiply Resistant Staphylococcus aureus) which has been a serious problem in our hospitals for many years, and Clostridium difficile, an emerging pathogen of increasing importance and which causes a very serious and chronic form of colitis in hospital patients. By studying the biochemical processes by which enzymes called recombinases excise and subsequently integrate antibiotic resistance elements from these bacteria and by determining the three dimensional structure of such enzymes we aim to determine the mechanism of action of members of this important enzyme family. The major outcomes of the project will be an increased understanding of one of the major processes by which antibiotic resistance determinants can spread both within and between bacterial pathogens of importance in the hospital environment. These studies will contribute towards the development of improved methods for controlling the spread of resistant pathogens and resistance genes in the hospital environment, with concomitant benefits to human health.Read moreRead less
Translating Bacterial Molecular Epidemiology Into Information To Improve Infectious Disease Risk Assessment And Control
Funder
National Health and Medical Research Council
Funding Amount
$494,500.00
Summary
Streptococcus pneumoniae (pneumococcus) and group B streptococcus (GBS) are important pathogenic bacteria, which cause septicaemia and meningitis in young infants, the elderly and people with certain chronic diseases. Both consist of a number of different types, some of which are more likely to cause disease than others. Pneumococcal vaccines that protect against the commonest pathogenic types are used in Australia in people most at risk.Antibiotic resistance is an increasing problem, which shou ....Streptococcus pneumoniae (pneumococcus) and group B streptococcus (GBS) are important pathogenic bacteria, which cause septicaemia and meningitis in young infants, the elderly and people with certain chronic diseases. Both consist of a number of different types, some of which are more likely to cause disease than others. Pneumococcal vaccines that protect against the commonest pathogenic types are used in Australia in people most at risk.Antibiotic resistance is an increasing problem, which should be partly off-set by immunisation. Giving antibiotics during labour, to women colonised with GBS, can reduce infection rates in newborns, but there are many disadvantages of this approach, including the risk of increased antibiotic resistance. Vaccines against GBS are mpt yet available. We have developed methods to identify detailed fingerprints of these bacteria which allow us to identify types, antibiotic resistance and, for GBS, other characteristics which can distinguish highly pathogenic strains from the majority that are carried harmlessly and unlikely to cause disease. The methods are still quite slow and expensive and produce complex patterns,which are difficult to interpret rapidly. We plan to develop a new, rapid and relatively inexpensive, fingerprinting system for these bacteria and computer programs to analyse and interpret the results. They will allow us to check the strains of pneumococci that cause disease to make sure that new ones, not covered by the vaccine, do not become more common and reduce the effectiveness of vaccine and that antibiotic resistance does not increase further. The methods will also allow us to study differences between the small proportion of GBS strains that cause neonatal infection and the majority that are carried harmlessly by pregnant women and are of little risk to their babies. Eventually this should allow doctors to identify women whose babies are most at risk, reduce unnecessary antibiotic use.Read moreRead less